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Angle-Meter NT User Manual

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1. Set Display Illum not used notused not used Set Field Signals 1 0 5 not used notused notused 31 10 15 Set Gain Corr 2 0 1 not used notused not used 30 30 31 Set Gain Mode 3 0 2 not used notused notused 30 13 15 Set Offset Corr 4 0 2 not used notused notused 29 29 31 Set Output Filter 5 0 1 not used notused notused 29 14 15 Set Output Mode 6 0 1 not used notused notused 28 30 31 Set Output Swing 7 0 4 not used notused notused 28 11 15 Set Power On Mode 8 0 1 not used notused notused 27 30 31 Set Processing 9 0 2 not used notused notused 27 13 15 Set Setups 10 0 4 not used notused not used 26 27 31 Set Test Signals 11 0 4 not used notused notused 26 11 15 Read Parameter 15 0 16 not used notused notused 24 0 15 Set Gain Corr Ch1 X 16 0 30 0 31 0 31 0 31 23 16 31 Set Gain Corr Ch2 X 17 0 30 0 31 0 31 0 31 23 0 15 Set Gain Corr Ch3 X 18 0 30 0 31 0 31 0 31 22 16 31 Set Gain Corr Ch4 X 19 0 30 0 31 0 31 0 31 22 0 15 Set Gain Corr Ch1 Y 20 0 30 0 31 0 31 0 31 21 16 31 Set Gain Corr Ch2 Y 21 0 30 0 31 0 31 0 31 21 0 15 Set Gain Corr Ch3 Y 22 0 30 0 31 0 31 0 31 20 16 31 Set Gain Corr Ch4 Y 23 0 30 0 31 0 31 0 31 20 0 15 Set Gain Corr Ch1 Z 24 0 30 0 31 0 31 0 31 19 16 31 Set Gain Corr
2. Typical progression of the output voltage Alpha horizontal in the Angular Data Mode 9 0 45 0 0 lt 5 45 9 0 0 90 180 270 360 Search coil angular orientation in the horizontal plane Typical progression of the output voltage Beta vertical in the Angular Data Mode 4 50 s 2 25 3 0 00 m 2 2 25 4 50 0 90 180 270 360 Search coil angular orientation in the vertical plane Drift measurement Notes 1 3 and 4 0 10 0 08 0 06 0 04 0 02 eee 0 02 0 04 0 06 0 08 0 10 0 20 40 60 80 100 120 Time minutes Horizontal Vertical Angle Meter NT User Manual page 62 Linearity Error and Crosstalk search coil horizontally turned over 360 vertically unmoved at 0 Notes 1 to 4 2 0 1 5 1 0 S 0 5 vo vo 2 o o 0 0 Bage a 0 5 1 0 1 5 2 0 0 45 90 135 180 225 270 315 360 Search coil angular orientation in the horizontal plane Linearity Error horizontal Crosstalk vertical Linearity Error and Crosstalk search coil vertically turned over 360 horizontally unmoved at 0 Notes 1 to 4 2 0 1 5 1 0 x w 0 5 p 00 6 E 0 5 ui 1 0 1 5 2 0 0 45 90 135 180 225 270 315 360 Sea
3. A A Ameja 1e3jeq JO uwous jauueyo Buunse ui euo luO 1109 youeag r J uilduie 1d ur awed 102 xog Bulyoyew A Sqad1 Joyeolpul pue SJOjeJedujo I Bojeuy sova asa oay SJBUBAUOD JOosse2o0Jgd lt JBUBAUOD lt a Boleuv IelI6iq jeuBis jey6iq ley6iq Bojeuy anjea uled pexi4 ujBueajs pier epo N ueg l npolN 1031293oq Y SOON SJOjelloso sova Si ljilduuy 4105 Slovene P J AOd Boleuv lIelI6iq jeoueunwN 39olO lnpoN 40 ye19U95 Figure 16 1 Block Diagram System Overview Angle Meter NT User Manual page 56 2S Gain Mode Yo Fixed Gain Value oO Y Control AGC Programmable Signal Output to ADC Gain Amplifier Search Coil Figure 16 2 Block Diagram Preamplifier Overview Y Control AGC control response time approx 100 ms J Emm gt Signal Output to ADC Jm Amplifier Vo 4 Vpp typ L Gain Variable i e dynamically regulated by the AGC Coil Figure 16 3 Block Diagram Preamplifier Gain Mode AGC Fixed Gain Value y Control J mm gt Signal Output to ADC Jm Amplifier Vo Vi Gain O Gain Fix i e preset by the Fixed Gain Value Coil Figure 16 4 Block Diag
4. gt BID FOP FOP CHN CHN RES RES RES BID Byte Identifier 1 B7 1 indicates a PacketlnfoByte The byte contains information in the remaining bits B6 B0 concerning the immediately following DataBytes Note that each PacketlnfoByte indicates the start of a data packet FOP Format of Packet 00 Angular Data The following DataBytes will transmit measuring data in the format Angular Data of the measuring channel number indicated by CHN 01 Vector Length The following DataBytes will transmit measuring data in the format Vector Length of the measuring channel number indicated by CHN 10 Vector Angle The following DataBytes will transmit measuring data in the format Vector Angle of the measuring channel number indicated by CHN 11 Parameter Data The following DataByte s will transmit the actual setting s of the requested parameter s Please note that CHN has no meaning if FOP 11 CHN Channel Number Angle Meter NT User Manual page 22 00 Channel 1 The following DataBytes will transmit measuring data of channel 1 in the format indicated by FOP 01 Channel 2 The following DataBytes will transmit measuring data of channel 2 in the format indicated by FOP 10 Channel 3 The following DataBytes will transmit measuring data of channel 3 in the format indicated by FOP 11 Channel 4 The following DataBytes will transmit measuring data of channel 4 in the format indicated by FOP RES Res
5. p lqeu u0no94102 18SJO 55v epow ureo l 45u27 101284 epoy jndino e Z Wd pue A Wd X Ud uo peseq Z 199A pue A 199A X 199A JO uoisueyxe UBIS Z lud pue A lud X Wd Z PEA A 199A X 199A eje nojeo OGV woy ejep uo peseq 44 OQV Woy ejeq Figure 17 1 Flowchart DSP Main Task Measuring Cycle Angle Meter NT User Manual page 58 18 Pinouts 18 1 Preamplifier Inputs 3 contacts socket connectors Pin 1 Pin 2 Pin 3 Search coil N C Search coil Suitable pin connectors for the search coils Binder series 719 part number 09 9747 00 03 18 2 Preamplifier Outputs Control Signals 15 contacts D SUB pin connector Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 5V GND 5V GND MUX A1 MUX AO GND Signal Pin 9 Pin 10 Pin 11 Pin 12 Pin 13 Pin 14 Pin 15 5V GND 5V Calc Meas Fix AGC N C Signal 18 3 Field Signals 9 contacts D SUB pin connector Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 Pin 9 Vf2 V f2 GND Vfl V fl GND Vf3 V f3 GND 18 4 Analog Outputs 15 contacts D SUB socket connector The meaning of the outputted voltages differs depending on the actual output mode Angular Data Signals alpha angular orientation in the horizontal plane and beta angular orientation in the verti
6. TR20 Hwy STD2 gt L ST2 2 gt ST1 2 gt t t gt gt 7 2 z 96 kHz C20 C21 C22 C23 g wy Sm gt STI gt sti 71 gt l i 45 gt E EE z Oscilloscope s mee gt S CHI X Deflection b 1 mV is equivalent to 1 mA lt log Oscill scilloscope i CH2 Y Deflection sane i 4 ap 5 TR30 PwZ OSTIT gt E ST2 7 gt ST1 7 gt 1 a N 120 kHz C30 c31 C32 C33 8 3 Cw STI 8 gt ST2 8 gt I STII8 gt i l 5 oo EI Tuning Adapter Matching Box Figure 15 2 Resonance Tuning Adapter Angle Meter NT User Manual page 53 E Angle Meter NT Enhanced Remote control Ej xi File Preferences General FiredGain GainCon OffsetCor The field signals of the Angle Meter NT are digitally synthesized by the Generator Module The Main Detector Module is capable to control their amplitudes The nominal voltages of the field signals are adjusted at the factory to ensure the specified magnetic flux density and an optimal field homogeneity at the 3D centre of the field coils Therefore the settings of the nominal field voltages should not be changed under normal circumstances The user has the opportunity to attenuate the nominal field voltages in steps of 20 downto zero by changing the setting of the general parameter Field Signals The Angle Meter NT uses relative values in the range from to 4095 in order to control the ampl
7. 0 0 0 5 1 0 1 5 2 0 Linearity Error and Crosstalk search coil vertically turned over 360 horizontally unmoved at 90 Notes 1 to 4 amp 5 45 90 135 180 225 270 315 360 Search coil angular orientation in the vertical plane Linearity Error vertical Crosstalk horizontal Angle Meter NT User Manual page 64 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 Angular noise on Ch 1 Alpha Beta 180 Distribution of angular noise Notes 1 to 4 amp 8 0 09 Angular noise on Ch 1 Alpha Beta 170 0 00 0 09 Angular noise on Ch 1 Alpha Beta 160 0 00 0 09 0 00 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 Angular noise on Ch 1 Beta Alpha 270 0 00 Angular noise on Ch 1 Beta Alpha 270 0 00 0 09 Angular noise on Ch 1 Beta Alpha 270 0 00 0 09 Angle Meter NT User Manual page 65 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 Angular noise on Ch 1 Alpha Be
8. Angle Meter NT User Manual SMM SASS SASSI induunud uwdudduuu nunumt wwwwwwwwwwwawa nun Scleral search coil system for linear detection of three dimensional angular movements 04090301 j Primelec D Florin Ostring 36 CH 8105 Regensdorf Switzerland http www primelec ch Table of Contents 1 Safety Information read this first u Q U 5 PAESI adidlJdm E 5 3 eric mero E 8 4 Base Dc IIR 8 5 Generator Mod le seeren aaae ieee r Ern r anne neu ieu E naro naa Fea Ene oe haya eran ea Fan Eme e Exe enin 8 6 Coil Frame Matching Box 9 T Search CONS oii u a tocebc idc Ro e ire de lin id d e os Ae UL ae cac KA ORE RR 10 9 Preamplifier iieri riter rene sl ay et e Pas ir wa is Ee ui vba Era Rena Ee ny Tai 10 9 Detector Module ii rere iiti pee ner masu ua Ee Pea aee a Iva Re Prae Tea 11 94 Display r sas 11 9 22 EEDS a I aaah ua qea masma ima a eta aaa tase ane exa te tate aaa wasy sqa saat 12 PCM CITUR 13 9 3 1 How to use the Menu Example menn 13 9 3 2 Menu Settings sonerie fe coetu teme op SEP so sob Fe ub Ped ee ene Ue xau pP s PR TR TU Pedal 15 10 Seriall terface u u ERR 21 10 1 Transmitted Data au uu u riley ede EV ie ai seas Dna es 21 10 1 1 Structure o
9. D14 DataByte Mid 21 Bit Parameter mim fs o fo ee fe D13 D12 D11 D10 D9 DataByte Lower 21 Bit Parameter er es es o e e ee 0 D6 D5 D4 D3 D2 D1 DO Angle Meter NT User Manual page 26 10 2 Received Data The setting of all parameters of the Detector Module may be achieved over the serial interface by the use of Remote Control Functions The Detector Module executes a certain Function after receiving a valid data packet from an external computer Each data packet consists of one FunctionByte one or several DataBytes one ControlByte and one TerminatorByte where the number of DataBytes within a packet depends on the type of the Function Notes e Neither the analog outputs nor the serial interface are updated with measurement data during the execution time of Remote Control Functions The analog outputs freeze at their last updated value and the serial interface is idle i e no measuring data is transmitted until the concerning Remote Control Function is executed e To disable the execution of any Remote Control Function push the Menu button of the Detector Module s during the power up sequence of the Angle Meter NT until the message Module Controls Disabled appears in the Display This prevents the execution of any Remote Control Function and ensures that the concerning Detector Module always updates the measurement data until the power of the device is switched off 10 2 1 Stru
10. a pepiens zzomy p Uld xog 6uiyoew aLpepeus zzomy vwoos t da p peus zzowv 6 Uld SIEUBIS pier4 8 Uld SIEUBIS pier4 Uld SIEUBIS pier4 Uld sieuDis pier4 Uld sieuDis pier4 Z Uld S eUBIS pier4 9 Uld SIEUBIS pier4 S Uld sieuDig pier4 t Uld sieuDis pier4 a z cep O A a z o P QN9 HA HA NR e ERR EA qe uini uo S A q 3x3 oiA q 3x3 sBury dijs Bumm 1983002 Bury dis sBurs diis 1NINV bunim 1ol99uuoS LN 193914 9 6UYy eureN jeu amp is euis Table 13 1 Slip Ring Wiring Angle Meter NT User Manual page 40 14 System Optimization The performance of the Angle Meter NT mainly depends on the following parameters e Homogeneity and strength of the magnetic field at the position of the search coil s e Effective area and geometry of the search coil s e Offset failures due to irradiation on the search coil signal s The system ground of the Angle Meter NT is internally connected to earth potential This should be considered if third party devices are connected to the Angle Meter NT since ground loops may occur under certain circumstances 14 1 Optimizing the Magnetic Field Homogeneity Due to the magnetic field search coil technique used by the Angle Meter NT an optimal quality of the magnetic field is the basic condition for reliable measurements Asymmetric field intensities crosstalk and phase errors lead to an inhom
11. 15 Data1 6 Causes the Detector Module to transmit the actual settings of the gain correction values for f3 Z axis of all four channels packet with four 21 Bit Parameter Note that the gain correction values are multiplied by 200000 for the transfer For a detailed description of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the gain correction values see Set Gain Corr above 15 Data1 8 Causes the Detector Module to transmit the actual settings of the fixed gain values of all four channels packet with four 14 Bit Parameter For a detailed description of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the fixed gain values see Set Gain Mode above Angle Meter NT User Manual page 35 Description F Data Description 15 Data1 12 Causes the Detector Module to transmit the actual settings of the offset correction values for f1 X axis of all four channels packet with four 21 Bit Parameter For a detailed description of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the offset correction values see Set Offset Corr above 15 Data1 13 Causes the Detector Module to transmit the actual settings of the offset correction values for f2 Y axis of all four channels packet with four 21 Bit Parameter For a detailed description
12. TR20 Core 36x23x15 Philips 3C11 EPCOS N30 PwrY EmA aU Scam bd 3 gt gt 96 kHz C20 C21 C22 C23 3 Q I Q 3 CY STI gt a 5 7 Front Back Coil X Left Right Coil Y Pu TS Top Bottom Coil Z Core 36x23x15 Philips 3C11 EPCOS N30 op bottom Cou PwZ _STI 7 gt E N n 30 n 45 S C30 C31 C32 C33 El 120 kHz O 5 3 CwZ STI 8 gt S 7 Notes 1 Capacitance values individually selected to tune for resonance at 80 kHz total capacitance 0 772 nF typ for sFieldCoils 70 cm 2 Capacitance values individually selected to tune for resonance at 96 kHz total capacitance 0 536 nF typ for sFieldCoils 70 cm 3 Capacitance values individually selected to tune for resonance at 120 kHz total capacitance 0 343 nF typ for sFieldCoils 70 cm 4 The specified turn ratio for TR10 TR20 and TR30 is valid for sFieldCoils 70 cm Coil frames with other dimensions may require an other turn ratio Figure 15 1 Example of a Matching Box Oscilloscope 180 gt CHI X Deflection 1 mV is equivalent to 1 mA ie L 180 gt oui scilloscope E VEO gt cup Y Defiection ne _GND gt IE n 4 TRIO PwX _STI 4 gt e ST2 4 gt _ST1 4 gt t i x 80 kHz C10 cu C12 c13 3 Bux STUS gt Sms Eno i L Oscilloscope Ber gt S CHI X Deflection 1 mV is equivalent to 1 mA E lat map ri amp Oscilloscope amp CH2 Y Deflection n 40 N
13. The output signals are available simultaneously in two forms as analog output voltages and as digital data over the serial interface The resolution of the output signals is 0 0879 where their update rate depends on the actual processing mode see below Processing Mode The digital data is scaled from 0 to 4095 for the angle alpha representing the range from 0 to 359 91 and from 1024 to 3072 for the angle beta representing the range from 90 to 90 The voltage swing of the analog outputs is adjustable see below Output Swing The figures below show the typical progression of the analog outputs where the output swing was set to 9 V Angle Meter NT User Manual page 45 Typical progression of the output voltage Alpha 9 0 45 ri 0 0 4 5 9 0 0 90 180 270 360 Angular orientation of the search coil in the horizontal plane Typical progression of the output voltage Beta 4 50 S 2 25 gt 0 00 m 2 2 25 4 50 0 90 180 270 360 Angular orientation of the search coil in the vertical plane Vector Length The output signals sVectLenX sVectLenY and sVectLenZ represent the spectral components of the three field frequencies f1 80 kHz X axis f2 96 kHz Y axis and f3 120 kHz Z axis of the induced voltage in the search coil Since the spectral frequency components are proportional to the horizont
14. I I I 80 100 120 T l T l l l 1 60 t us 120 80 120 t us t us pu m e s s l l po SAEPE JA a a L l l l l s x a ey A e x A lt q q eBeyoA oBeyoA oeBeyoA eBeyoA ex o o S to eo e e e 5 A 5 5 25 j to e eo a 2 Table 2 1 Correlation Examples Angle Meter NT User Manual page 7 3 Concept The Angle Meter NT mainly consists of four functional blocks e The base unit with the Generator Module and one or two Detector Module s e The coil frame arranged as a cube which generates three magnetic fields e The search coil s placed in the 3D centre of the generated magnetic field e The preamplifier s for the amplification of the search coil signal s The Generator Module generates three sine wave signals of different frequencies The signals are amplified by three power amplifiers within the Generator Module The amplified voltages are applied via the Matching Box to the coil frame The resulting magnetic field induces a voltage in a search coil which is pre processed in the preamplifier In the Detector Module the signal is digitized processed by a digital signal processor and outputted as analog and digital data 4 Base Unit The base unit of the Angle Meter NT is designed in a modular form It consists of the power supply one Generat
15. and the possible risk for injuries to health before using the Angle Meter NT Under no circumstances may the Angle Meter NT be used for applications on the human being Only qualified personnel may work on the system and only after becoming familiar with the concerning standards and regulations safety notices and the functional principle of the Angle Meter NT In no event shall Primelec its employees or its suppliers be liable for any damages whatsoever 15 1 Coil Frame The coil frame should consist of three field coils X Y and Z coil each with two windings Depending on the size of the coil frame the required field coil current i e the resonance current is up to 20 A This must be considered for the evaluation of the material used for the coil frames and the wiring Aluminium bars cross section 8 x 8 mm may be used for the coil frames Two copper wires with 1 5 mm2 in parallel are suggested for the wiring The connection wires must be twisted carefully in order to prevent stray fields and unwanted additional inductance 15 2 Matching Box 15 2 1 Transformers The Matching Box contains application specific transformers The turn ratio depends on the size of the used coil frame Coil frames below 50 cm have 1 1 transformers coil frames between 50 cm and 70 cm have 1 1 5 transformers in order to achieve higher field voltages The use of coil frames larger than 70 cm is not recommended The transformers are based on fe
16. centre of the coil frame picks up a signal The spectral frequency components for f1 f2 and f3 of the induced signal are proportional to the angular displacements of the search coil relative to the system s reference frame see chapter 2 Measuring principle As mentioned the search coils should be placed at the 3D centre of the coil frame since the homogeneity of the magnetic field is optimal in that position If this is not practicable the linearity of the output data may decrease To avoid this in a certain range the Angle Meter NT allows an individual gain calibration for the X Y and Z signals of each measuring channel see chapter 14 3 Use of the gain correction The search coils may be manufactured by the user to achieve best results and highest flexibility for the specific application but of course the Angle Meter NT is also compatible with the search coils of third party suppliers The diameter and the number of turns determine the effective area of the search coil Aeff n D pi 4 The effective area of the search coil is one of the main parameter which determine the quality of the measurement data The larger the effective area the better the signal to noise ratio the smaller the diameter the better the linearity To achieve optimal results the parameters of the used search coils must comply with the specification of the technical data 8 Preamplifier The preamplifier is capable to process four search coils signal
17. is 5 V The setting for the fixed gain value is too high a B Induced search coil voltage Vector Lengths Output Voltage f1 41025 Vf1 5 000 V f2 36 Vf2 0 005 V f3 39 Vf3 0 005 V 0 0 Voltage Angle Meter NT User Manual page 47 f1 41 Vf1 0 005 V 90 0 f2 41032 Vf2 5 000 V f3 38 Vf3 0 004 V n fi 20513 Vf1 2 564 V 45 45 f2 20515 Vf2 2 564 V gt f3 29013 Vf3 3 627 V Table 14 5 Output Mode Example 2 As one can see are the analog output voltages incorrect at certain angular orientations of the search coil The DACs are saturated due to the incorrect setting of the fixed gain value which is too high in this example It is recommended to execute the function Do Auto Tune in the Gain Mode Menu in order to achieve optimal settings for the fixed gain values This function determines the optimal settings for the fixed gain values of all four measuring channels in the Detector Module However if a search coil is placed outside of the 3D centre of the field coils this function may determine incorrect fixed gain values under certain circumstances depending on the angular orientation of the search coils during the execution of the function The user should check the determined settings by turning the search coil s over the relevant range and check the analog output signals for saturation eff
18. is set to Fixed the scaling of the output voltages is fixed The scaling is based on a vector length of 40000 This may be useful to subtract offsets externally For details see chapter 14 5 Choosing the best suited settings for your application See also the pinout of the connector with the analog outputs The format of the digital data is described in chapter 10 1 Transmitted Data For information concerning the processing speed and the resulting update rate of the outputs see Set Processing below Data1 2 Vector Angle The signed vector angles for f1 X axis f2 Y axis and f3 Z axis from the FFT calculations are available as analog outputs and as digital data over the serial interface The voltage swing of the analog outputs is adjustable see Set Output Swing The output voltages are scaled to the range from pi to pi See also the pinout of the connector with the analog outputs The format of the digital data is described in chapter 10 1 Transmitted Data For information concerning the processing speed and the resulting update rate of the outputs see Set Processing below Set Output Swing N Data1 0 The range of the voltage swing of the analog outputs is set to 2 5 Volt Data1 1 The range of the voltage swing of the analog outputs is set to 4 5 Volt Angle Meter NT User Manual page 32 Description F Data Description Data1 2 T
19. must be considered The correct settings for the field voltages depend on the size of the coil frame the used transformers the quality of the resonance circuits and the frequency of the field signals The setting of the nominal field voltages is accomplished with the program Angle Meter NT Enhanced Remote Control over the serial interface RS 232 of the Angle Meter NT see the figures at the end of this chapter Once the field voltages are exactly calibrated the system can be used with various search coils without the need for recalibration of the field voltages 15 3 1 Coarse Tuning Adjust the three nominal field voltages to achieve the typical magnetic flux densities at the 3D center of the coil frame which are 15 uT 80 kHz X axis 12 5 uT 96 kHz Y axis and 10 uT 120 kHz Z axis Tune the nominal field voltages one by one until the typical flux density is achieved in each axis Do not overload the power amplifiers max 350 mA output current per channel with ohm resistive load i e exactly tuned resonance circuits assumed 15 3 2 Fine Tuning A fine tuning of the nominal field voltages is required to calibrate the magnetic field at the 3D center of the coil frame Adjust the nominal field voltages in small steps until the induced voltage in a given search coil which is placed at the 3D centre of the coil frame is equal in all three axes See table on next page for details Angle Meter NT User Manual page 51 Step
20. of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the offset correction values see Set Offset Corr above 15 Data1 14 Causes the Detector Module to transmit the actual settings of the offset correction values for f3 Z axis of all four channels packet with four 21 Bit Parameter For a detailed description of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the offset correction values see Set Offset Corr above 15 Data1 16 Causes the Detector Module to transmit the actual settings of the relative values for the field voltages U f1 U f2 and U f3 packet with three 14 Bit Parameter The field voltages are adjusted at the factory for an optimal field homogeneity at the 3D centre of the coil frame Therefore they should remain unchanged and are read only values for the user However if you plan to change these values for some reasons please contact Primelec for the suitable software tool Set Gain Corr ChN fM 27 Data1 MostUpper Data2 Upper Data3 Lower Data4 MostLower Sets the gain correction value for channel N frequency M The allowed range of the gain correction values is between 0 0 and 5 0 Note that the gain correction values are multiplied by 200000 for the transmission For a detailed description of the usage of the gain correction values see Set Gain Corr above Set Gai
21. only applicable at the Main Detector Module i e the field signals will not change if function 1 is sent to the Add On Detector Module e Function 15 Read Parameter causes the Detector Module to transmit the actual setting of a certain parameter indicated by the content of DataByte1 see table below 10 2 4 Remote Control Functions Meaning of the DataByte s Description F Data Description Set Display llum O Data1 0 The backlight of the LCD is turned off 0 Data1 1 The backlight of the LCD is dark 0 Data1 2 The backlight of the LCD is medium 0 Data1 3 The backlight of the LCD is bright Set Field Signals 1 Data1 0 The field signals are turned off Please note 1 Data1 1 The field signals are attenuated to 20 of their nominal This function is value licable at be Mn dec 1 Data1 2 The field signals are attenuated to 40 of their nominal Module value 1 Data1 3 The field signals are attenuated to 60 of their nominal value 1 Data1 4 The field signals are attenuated to 80 of their nominal value 1 Data1 5 The field signals are at 100 of their nominal value Set Gain Corr 2 Datal 0 The gain correction is disabled not active Data1 1 The gain correction is enabled active and the output data of all four measuring channels is calculated on the basis of the individual gain correction values for each frequency of each channel This means that the signed vecto
22. or frequency coding by driving the external magnetic fields in phase quadrature or at different frequencies 2 In order to obtain reproducible results the search coil measurements have to be restricted to the uniform part of the external magnetic fields The Angle Meter NT uses an other approach to detect the angular orientation of a search coil Three digitally synthesized sine wave signals of different frequencies are used to generate a magnetic field This field induces a voltage in a search coil where the spectral frequency components of the three field frequencies are proportional to the horizontal and vertical angular displacements of the search coil relative to the system s reference frame The spectral frequency components are obtained by computing the Fast Fourier Transformation FFT of the digitized search coil signal The use of a high performance digital signal processor DSP allows to compute the FFT and all required trigonometric calculations in real time 1 D A Robinson A method of measuring eye movement IEEE Trans Biomed Eng vol BME IO pp 137 145 1963 2 R S Remmel An inexpensive eye movement monitor IEEE Trans Biomed Eng vol BME 31 pp 388 390 1984 Angle Meter NT User Manual page 5 The left part in the figure below schematically shows a search coil placed at the center of the magnetic fields of the field coils X X 80 kHz and Y Y 96 kHz For simplicity only two axes are shown In
23. over the serial interface see chapter 10 2 3 Remote Control Functions The LEDs of the Detector Module indicate the voltage level of the concerning measuring channels if the fixed gains are adjusted correctly the concerning LEDs light green see chapter 9 2 LEDs Note that the peak value of the voltage changes depending on the angular orientation of the search coil see chapter 2 Measuring principle 3 Do Auto Tune First the user has to prepare the tuning process by placing the used search coils into their positions in the field where their angular orientations doesn t matter Then the Auto Tuning can be started The system performs a routine which evaluates the optimal gain for each channel regarding the currently connected search coils where their actual angular orientation is considered by the routine The execution time of the routine depends on the effective area of the used search coils max 3 seconds After the routine has performed the evaluated gains are used fixed gain values and the Module is set to the fixed gain mode See also above Fixed gain mode E Offset Corr 0 Off AGC The offset correction is disabled not active and the setting can not be changed because of the gain mode is currently set to AGC If you want to use the offset correction the gain mode of the Module must be set to Fixed see above D Gain Mode 1 Disabled The offset correction is disabled not
24. preamplifier may be helpful aluminum copper or permalloy 14 3 Use of the Gain Correction If a search coil is placed in the inhomogeneous area of the magnetic field the outputs of the measuring channel are no longer directly proportional to the angular displacements of the search coil relative to the system s reference frame This is the case if the search coils are outside the 3D centre of the coil frame or if the magnetic fields are damped asymmetrically The gain correction of the Angle Meter NT allows the correction of such linearity errors in a certain range If the gain correction is enabled active the outputs of the measuring channels are calculated on the basis of the individual gain correction values for each frequency of each channel This means that the signed vector lengths from the FFT calculations are multiplied by the concerning gain correction values If the actual gain mode is set to AGC the influence of the gain correction is limited To achieve the full influence of the gain correction use the fixed gain mode The table below shows the measuring signal and the resulting signed vector lengths from the FFT calculations without gain correction Signed vector lengths from the CS eum EEE no ina FFT calculations scaled to 1 The search coil is placed within the homogeneous area of the magnetic field with angular orientations alpha 45 and beta 45 sVectLenX 0 5 sVectLenY 0 5 sVectLenZ 0
25. suggested processing mode to achieve the highest available update rates depending on the number of the used search coils Search Angle Meter NT is equiped Angle Meter NT is equipped with two Detector Modules Coils with one Detector Module Main Detector Module Add On Detector Module 1 Ch1 gt Ch1 Ch1 gt Ch1 Not used 2 Ch1 gt Ch2 Chi Ch1 Chi Ch1 3 Ch1 gt Ch4 Chi gt Ch2 Chi gt Ch1 4 Ch1 gt Ch4 Chi gt Ch2 Chi gt Ch2 5 Chi gt Ch4 Chi gt Ch1 6 Chi gt Ch4 Chi gt Ch2 7 Chi gt Ch4 Chi gt Ch4 8 Chi gt Ch4 Chi gt Ch4 Table 14 7 Processing Mode Suggestions Angle Meter NT User Manual page 49 15 Tuning the System with a new Coil Frame This chapter describes the required steps to setup a suitable Matching Box and to tune the field voltages if the user plans to fabricate a specific coil frame A Caution The coil frames of the Angle Meter NT generate a relatively strong magnetic field in the frequency range from 80 kHz to 120 kHz This can lead to injury to health Capacitive and inductive coupling onto organisms and devices sensitive in this regard must be considered The signals applied to the coil frames may have hazardous voltage levels An inappropriate application touching the conductors or the coil frames capacitive and or inductive couplings etc can come for injuries to health Check the standards and regulations of your country
26. switch at the front panel is used to toggle the operation mode of the device between Power On and Standby where the Standby mode means that all internal electronics are not powered except the small auxiliary power supply used by the front switch Angle Meter NT User Manual page 8 6 Coil Frame Matching Box The field signals from the Generator Module are applied to the Matching Box Within the Matching Box the field signals are applied via three transformers to the capacitor networks which build the capacitive part of three resonance circuits Three pairs of one turn field coils arranged as a cube are building the inductive part of the resonance circuits The capacitor networks are tuned at the factory to adjust the resonance circuits to 80 kHz 96 kHz and 120 kHz The currents in the field coils generate three magnetic fields 80 kHz for the X axis 96 kHz for the Y axis and 120 kHz for the Z axis As mentioned the amplitudes of the field signals are tuned at the factory to achieve the specified flux density and an optimal homogeneity of the magnetic field at the 3D centre of the coil frame This means that the used search coils must be placed in the 3D centre of the coil frame to achieve an optimal system linearity The usable space with an acceptable field homogeneity around the 3D centre of the coil frame is more or less proportional to the size of the coil frame Therefore larger coil frame are preferable in this regard Primelec o
27. the system is wired the Angle Meter NT can be turned on The main switch at the rear panel of the Angle Meter NT may remain switched on except during system wiring and the switch at the front panel of the Generator Module is used to toggle the operation mode of the device between Power On and Standby where the Standby mode means that all internal electronics are not powered except the small auxiliary power supply for the front switch Caution Do not remove or insert the Removable Bars while the system is operating Turn off the power of the Angle Meter NT before handling the bars Angle Meter NT User Manual page 39 13 Slip Ring Wiring If slip rings are required e g if a Turn Table is used use the following table to avoid problems Q0IM pesn aJe g 01 OL sieuBis si ljilduue iq Z sjauueyo Buunseeui g 104 Jeuijduieaug sieuueuo Bulinse uu p JO pesn ae g 01 0 sieuBis sjoejuoo Buu dijs au jo jnoAe eyeudoudde esf peziwiulw eq 1snui s euBis 1eujo 0 L amp 39Z pue 997 GRP TRL S EUBIS WOY yje sso1O yyeySsouo euBis JEWIUILU 10 pepueuJooaJ ase sjoejuoo Hunu dijs a esedas oe uoo Bu dijs uues y esn Aew GND 8 pue 6 9 g sieuBis Auoo u pl q www diu rose u pl g 5 e pjerus UOWWOD pZ OMY Sed pejsiM t 8 0 OL sieuBIS 104 j qeO pepusWLUODEY uoo u pl q www diu 2428 uepjeg 5 e spierus sed ZZ OMY Sled peisi 6 0 sieuBIS 40 ejqe pepueuiuo2es y Uld jeyidue
28. to an individual fixed value This allows the use of an offset correction which will minimize the influence of picked up stray signals see also below Set Offset Corr Please note that the fixed gain values are relative values in the range from 0 to 255 If the fixed gain mode is selected the values of the fixed gains must be individually adjusted for the used search coils This can be done automatically by the use of the Remote Control Function Do Auto Tune concerning Gain Mode see below To change the values manually use the concerning Remote Control Function over the serial interface see below Set Gain Fix ChN The LEDs of the Detector Module indicate the voltage level of the concerning measuring channels if the fixed gains are adjusted correctly the concerning LEDs light green see chapter 9 2 LEDs Note that the peak value of the voltage changes depending on the angular orientation of the search coil see chapter 2 Measuring principle Data1 2 Do Auto Tune concerning Gain Mode First the user has to prepare the tuning process by placing the used search coils into their positions in the field where their angular orientations doesn t matter Then the Auto Tuning can be started The system performs a routine which evaluates the optimal gain for each channel regarding the currently connected search coils where their actual angular orientation is considered by the routine The execution time of the ro
29. to zero as achievable e Vector length for Ch1 f3 sVectLenZ has a value as close to zero as achievable Do not move the position but vary only the angular orientation of the search coil Fix the search coil once it has an angular orientation such that these conditions are true The search coil should now have an orthogonal orientation relative to the coil frame axis X anda parallel orientation relative to the coil frame axes Y and Z Note the value of the vector length for Ch1 f1 sVectLenX MAX for later use in steps 6 and 7 Turn the search coil accurately until all of the following conditions are true e Vector length for Ch1 f1 sVectLenX has a value as close to zero as achievable e Vector length for Ch1 f2 sVectLenY has the maximal achievable value e Vector length for Ch1 f3 sVectLenZ has a value as close to zero as achievable Do not move the position but vary only the angular orientation of the search coil Fix the search coil once it has an angular orientation such that these conditions are true The search coil should now have an orthogonal orientation relative to the coil frame axis Y and a parallel orientation relative to the coil frame axes X and Z Use the program Angle Meter NT Enhanced Remote Control to increase or decrease the relative value of the nominal field voltage U f2 96 kHz Y axis until the value for Ch1 f2 is equal to sVectLenX_MAX see step 5 Turn the search coil accurately until al
30. 100 100 80 80 o 60 60 40 40 20 20 0 0 0 18 0 09 0 00 0 09 0 18 0 09 0 00 0 09 0 18 Angle Meter NT User Manual page 69 Distribution of angular noise cont Notes 1 to 4 amp 6 amp 8 Angular noise on Ch 1 Alpha Beta 120 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 o 60 60 40 40 20 20 0 s 28388328 0 we F oF 0 09 0 00 0 09 Angular noise on Ch 1 Alpha Beta 110 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 o 60 60 40 40 20 20 0 aoae e 2 S Q a 0 Q FFF 0 09 0 00 0 09 0 18 Angular noise on Ch 1 Alpha Beta 100 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 o 60 60 40 40 20 20 0 0 0 62 0 44 0 26 0 09 0 09 0 26 0 44 0 62 0 79 0 09 0 00 40 09 Angle Meter NT User Manual page 70 Distribution of angular noise Notes 1 to 4 amp 6 to 8 Angular noise on Ch 1 Alpha Beta 100 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 60 60 40 40 20 20 0 a qq lt e 2 8 0 fF FF 9 EF 0 09 0 00 Note1 Measurement executed with 8 channels working i e max internal power dissi
31. 2 Galli MOGdG ara uu nin tuti eR buda eta Gaerne 44 14 5 3 Gain Correction Offset Correction 45 14 54 Output Filter r 45 14 5 5 QUID MOS iie aula ep e ridere rule ania 45 14 5 6 O tput SWING ubi a ire n ro d up A EA E a pu nan edt 48 14 55 GIBTOESSSITISTVIOUG irte p Pte iod Etui m te tu tad itt uice iue 49 15 Tuning the System with a new Coil Frame eese 50 15 1 COI Frame RN 50 15 2 Matchirig BOXx niii Linee DU once Loco n celu c Eine ce fe Lione ask awa 50 15 2 1 Transformers 525203 sac soc ase sad soca IINE ICME 50 15 2 2 RESONANCE Circuit TUNING a6 o ets ene eden ee ek es 50 Angle Meter NT User Manual page 2 15 3 Field Voltage TuNiNg eco ek eee Hte det o caben sa cese secu det desees ooa diaaa 51 15 3 1 Coarse TUMM eos e Liane oro Gto aep re er he ioe oe A ATAS 51 15 3 2 Eine TUPITIO S oie aea ere eiua uctus M DELIA IM Pone uM PL od 51 JL ESO ee i kusa 53 16 Block Dido AMS ul u II demetetecchecereduauteiwncteubiecunedstecchevetedavieiwucterbtwcumedsteustedin 56 T C PLOW CIN ANE sas u u muu us AE sai St Riau sasa 58 18 PiNOUtS ua adansonii ananasa daea aana a adan ar A anaa aa anaa Aaea rnale e aena Saai anaal ihanda ani 59 18 1 Preamplifier Inputs 3 contacts socket connectors 59 18 2 Preamplifier Outputs Control Signals 15 contacts D SUB pin
32. 7071 The search coil is placed outside the homogeneous area of the magnetic field with angular orientations alpha 45 and beta 45 sVectLenX 0 475 sVectLenY 0 36 sVectLenZ 0 6081 Voltage Table 14 1 Gain Correction Example To determine the gain correction values place the search coil into their position in the field with an angular orientation alpha 45 and beta 45 The output mode Vector Length provides the signed vector lengths from the FFT calculations where the gain correction should be disabled at this time in order to avoid false results due to eventually existing invalid gain correction values After scaling the captured signed vector lengths to 1 the gain correction values can be calculated gainCorrX 0 5 sVectLenX gainCorrY 0 5 sVectLenY gainCorrZ 0 7071 sVectLenZ All gain correction values are set to 1 0 at the factory To change the values use the concerning Remote Control Function over the serial interface Angle Meter NT User Manual page 42 After the valid gain correction values have been set and the gain correction was enabled the system linearity is improved Note that all gain correction values are permanently stored non volatile in the Detector Module 14 4 Use of the Offset Correction Picked up stray signals on the measuring signal may lead to offsets and or noise on the output signals Stray signals may be picked up b
33. Ch2 Z 25 0 30 0 31 0 31 0 31 19 0 15 Set Gain Corr Ch3 Z 26 0 30 0 31 0 31 0 31 18 16 31 Set Gain Corr Ch4 Z 27 0 30 0 31 0 31 0 31 18 0 15 Set Gain Fix Ch1 28 0 7 0 31 not used notused 17 24 31 Set Gain Fix Ch2 29 0 7 0 31 not used notused 17 8 15 Set Gain Fix Ch3 30 0 7 0 31 not used notused 16 24 31 Set Gain Fix Ch4 31 0 0 31 not used notused 16 8 15 Set Offs Corr Ch1 X 32 0 31 0 31 0 31 0 31 15 16 31 Set Offs Corr Ch2 X 33 0 31 0 31 0 31 0 31 15 0 15 Set Offs Corr Ch3 X 34 0 31 0 31 0 31 0 31 14 16 31 Set Offs Corr Ch4 X 35 0 31 0 31 0 31 0 31 14 0 15 Set Offs Corr Ch1 Y 36 0 31 0 31 0 31 0 31 13 16 31 Set Offs Corr Ch2 Y 37 0 31 0 31 0 31 0 31 13 0 15 Set Offs Corr Ch3 Y 38 0 31 0 31 0 31 0 31 12 16 31 Set Offs Corr Ch4 Y 39 0 31 0 31 0 31 0 31 12 0 15 Set Offs Corr Ch1 Z 40 0 31 0 31 0 31 0 31 11 16 31 Angle Meter NT User Manual page 28 Set Offs Corr Ch2 Z 0 31 0 31 0 31 0 31 0 15 Set Offs Corr Ch3 Z 42 0 31 0 31 0 31 0 31 10 16 31 Set Offs Corr Ch4 Z 43 0 31 0 31 0 31 0 31 10 0 15 Table 10 4 Remote Control Functions Overview Notes e Functions not explicitly listed 12 14 44 63 are reserved for factory used functions or future use respectively e Function 1 Set Field Signals is
34. Instruction Connect a computer to the serial interface RS 232 of the Angle Meter NT The program Angle Meter NT Enhanced Remote Control must be installed on the computer Use the following settings for the Angle Meter NT Field Signals 100 Gain Correction Disabled Gain Mode Fixed Offset Correction Disabled Output Filter Disabled Output Mode Vector Length Output Swing 10 V if this overshoots the maximal input voltage range of the used external data acquisition system use the maximal admissible output swing instead e Processing Ch1 gt Ch4 e Test Signals Off Place a search coil at the 3D center of the coil frame and connect it to Channel 1 of the Preamplifier Any search coil with specifications as described in the technical data of the Angle Meter NT may be used Do not move the position of the search coil within the coil frame during the following steps i e vary only the angular orientation of the search coil if prompted Use the program Angle Meter NT Enhanced Remote Control to set an adequate fixed gain value for Channel 1 you may use the function Do Auto Tune of the Gain Mode to evaluate an adequate value The level indicator LED of Channel 1 must be green Turn the search coil accurately until all of the following conditions are true e Vector length for Ch1 f1 sVectLenX has the maximal achievable value e Vector length for Ch1 f2 sVectLenY has a value as close
35. N Data1 2 Do Auto Tune concerning Offset Correction First the user has to prepare the tuning process by placing the used search coils into their positions in the field and shielding them completely so that they can not pick up a field signal Therefore under optimal conditions there is now no signal from the search coil If there is a remaining signal this is the picked up stray signal which has to be eliminated to achieve optimal output data Then the Auto Tuning can be started The Detector Module performs a routine which detects the present input signal at each channel which is in fact the picked up stray signal only Therefore the signed vector lengths from the FFT calculations during the routine are the offset correction values for the later use The execution time of the routine is approximately 2 seconds After the routine has performed the offset correction of the Module is enabled and the detected offset correction values are used See also above Enabled offset correction Set Output Filter c1 Data1 0 The digital filter is disabled not active Data1 1 The digital filter is enabled active and the output signals of all four measuring channels are feed trough the digital filter This means that the signed vector lengths from the FFT calculations are feed trough a digital IIR Filter 6 order Butterworth low pass filter implemented on the DSP with a cutoff frequency of
36. See description above DataBytes UpperX UpperY UpperZ m m m Sign D12 D11 D10 D9 Databytes LowerX LowerY LowerZ or e ew e w sTo 0 D6 D5 D4 D3 D2 D1 D0 10 1 2 4 Parameter Data The actual settings of all parameters of the Detector Module can be requested over the serial interface by the use of the Remote Control Functions Read Parameter see chapter 10 2 3 Remote Control Functions The actual setting of the requested parameter is transmitted on request once in a data packet consisting of one PacketinfoByte plus one or several DataBytes The number of DataBytes and the format of the DataBytes 7 Bit Parameter 14 Bit Parameter or 21 Bit Parameter depends on the requested parameter 7 Bit Parameter PacketInfoByte Data Data Ls 14 Bit Parameter PacketlnfoByte UpperData LowerData 14 Bit Data 21 Bit Parameter PacketlnfoByte UpperData MidData LowerData 21 Bit Data Ld PacketlnfoByte See description above DataByte 7 Bit Parameter er e es e a To 0 D6 D5 D4 D3 D2 D1 DO Angle Meter NT User Manual page 25 DataByte Upper 14 Bit Parameter m m D13 D12 D11 D10 D9 DataByte Lower 14 Bit Parameter m s gt 0 D6 D5 D4 D3 D2 D1 D0 DataByte Upper 21 Bit Parameter fer es os ees 9 0 Sign D19 D18 D17 D16 D15
37. Z axis The Detector Module has several parameters which determine the behavior of the Module e The format of the output signals e The processing of the measuring channels e The gain mode for the amplification of the search coil voltage e The internal output filter e The individual correction of offsets due to picked up stray signals e The individual correction of gains due to nonlinearity e The output voltage swing of the analog outputs To change the settings of these parameters use the menu or the Remote Control Functions over the serial interface See chapters 9 3 Menu and 10 2 3 Remote Control Functions for a detailed description of the parameters and how to change their settings See also chapter 14 5 Choosing the best suited settings for your application 9 1 Display During normal operation the display LCD of the Detector Module shows the actual settings of some important parameters OM Output Mode The actual mode format of the output signals D Angular Data angular orientation of the search coil with the calculated angles alpha horizontal plane and beta vertical plane L Vector Length signed vector length from the FFT calculation for f1 X axis f2 Y axis and f3 Z axis A Vector Angle signed phase angle from the FFT calculation for f1 f2 and f3 Angle Meter NT User Manual page 11 PR Processing The actual processing mode of the measuring channels 1 Only one measuring cha
38. active 2 Enabled The offset correction is enabled active and the output data of all four measuring channels is calculated on the basis of the individual offset correction values for each frequency of each channel This means that the concerning offset correction values are subtracted from the signed vector lengths from the FFT calculations If the search coil signal is not clean i e if there are picked up stray signals on the measuring signal this allows to minimize the influence of the stray signals on the output signals See also chapter 14 4 Use of the offset correction Note that all offset correction values are set to zero at the factory If the offset correction is enabled the offset correction values must be individually adjusted for each frequency of each measuring channel This can be done automatically by the use of the menu Do Auto Tune see below To change the values manually use the concerning Remote Control Function over the serial interface see chapter 10 2 3 Remote control functions Angle Meter NT User Manual page 16 Parameter Setting Description 3 Do Auto Tune First the user has to prepare the tuning process by placing the used search coils into their positions in the field and shielding them completely so that they can not pick up a field signal Therefore under optimal conditions there is now no signal from the search coil If there is a remaining signal t
39. al and vertical angular displacements of the search coil relative to the system s reference frame coil frame they can be used to calculate the angular orientation alpha and beta of the search coil The output signals of this output mode are comparable to the outputs delivered by a conventional analog phase locked amplitude detection system where the advantages of the digital signal processing used by the Angle Meter NT still are available This output mode is used to obtain the needed information to determine the correction values used by the gain and offset correction functions Furthermore this output mode may be used if your application includes the recording of torsional eye movements The output signals representing the signed vector lengths from the FFT are simultaneously available in two forms as analog output voltages and as digital data over the serial interface where their update rate depends on the actual processing mode see below Processing Mode In this output mode the scaling of the analog output voltages depends on the actually used gain mode If the gain mode is set to AGC the output voltages are always scaled to fit the dominant vector in order to make full use of the available dynamic range If the gain mode is set to Fixed the scaling of the output voltages is fixed The scaling is based on a vector length of 40000 Vector lengths larger than 40000 will saturate the DACs without any notice which will lea
40. all gain correction values are set to 1 0 at the factory To change the values use the concerning Remote Control Function see chapter 10 2 3 Remote Control Functions D Gain Mode T AGC The gain mode of all four measuring channels is set to automatic gain control AGC This allows the use of different search coils without the need of any system recalibration as long as the parameters of the used search coils are within the technical specifications Due to the AGC the gains change dynamically depending on the field strength the effective area of the used search coils and their angular orientation This ensures an optimal signal to noise ratio of the system Note that in this mode the offset correction is always disabled it is not applicable due to the variable gain caused by the AGC see also below E Offset Corr Angle Meter NT User Manual page 15 Parameter Setting Description 2 Fixed The gain of all four measuring channels is set to an individual fixed value This allows the use of an offset correction which will minimize the influence of picked up stray signals see also below E Offset Corr If the fixed gain mode is selected the values of the fixed gains must be individually adjusted for the used search coils This can be done automatically by the use of the menu Do Auto Tune see below To change the values manually use the concerning Remote Control Function
41. ays green independently of the angular orientation of the connected search coil The concerning LED of a used measuring channel should always light green to ensure reliable output data Angle Meter NT User Manual page 12 9 3 Menu The settings of the parameters of each Detector Module is achieved by the menu or over the serial interface This chapter describes the use of the menu The menu allows to change the settings of the following parameters e The intensity of the display illumination LCD backlight e The strength of the magnetic field e Enable disable the correction of gains due to nonlinearity e The gain mode for the amplification of the search coil voltage e Enable disable the correction of offsets due to picked up stray signals e Enable disable the digital filter for the output signals e The mode format of the output signals e The output voltage swing of the analog outputs e The behavior of the Module at power on e The processing of the measuring channels e The saving and recalling of settings e The output of some test signals To enter the menu during normal operation push the knob of the multifunctional rotary push button of the Detector Module for a time longer than one second During the menu is active turn the knob to select the desired parameter To change the setting of the selected parameter push the knob for a time shorter than one second and choose the new setting by turning the knob To enter th
42. cal plane of the processed channels are outputted at the indicated pins Vector Length Signals sVectLenX f1 X axis sVectLenY f2 Y axis and sVectLenZ f3 Z axis of the processed channels are outputted at the indicated pins Vector Angle Signals sVectAngX f1 X axis sVectAngY f2 Y axis and sVectAngZ f3 Z axis of the processed channels are outputted at the indicated pins Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 Ch1 alpha Ch1 beta Ch2alpha Ch2 beta Ch3alpha Ch3 beta Ch4 alpha Ch4 beta or Ch1f1 or Ch1 f2 or Ch1f3 or Ch2f1 or Ch2f2 or Ch2f3 or Ch3f1 or Ch3f2 Pin 9 Pin 10 Pin 11 Pin 12 Pin 13 Pin 14 Pin 15 GND GND GND Ch4 f3 Ch4 f2 Ch4 f1 Ch3 f3 18 5 Serial Interface RS 232 9 contacts D SUB socket connector An external computer COM port may be connected with a straight male female interface cable Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 Pin 9 N C TxD RxD N C GND N C CTS RTS N C Angle Meter NT User Manual page 59 19 Technical Data In General Number of measuring channels AC input voltage Power consumption LC Display Control elements Dimensions Mass Field signal generation In general Frequencies Maximum output voltage Nominal output voltages Output impedance Power bandwidth Coil frame In general Frame material Frame dimensions Frame color
43. connector 59 18 3 Field Signals 9 contacts D SUB pin connector 59 18 4 Analog Outputs 15 contacts D SUB socket connector 59 18 5 Serial Interface RS 232 9 contacts D SUB socket connector 59 19 T ch nical Data u IEEE EDU 60 20 Personal Notes 5 eror rece anu az giaa eo dra Fono vo oca sz asua 72 List of Figures Figure 2 1 Measuring Principle opi te nee ance s eoo oe ox e Spon aus fne ee oos Gee odo os 6 Figure 4 1 Base unit with the Generator Module and the Main Detector Module 8 Figure 4 2 Base unit plus Add On Detector Module 8 Figure 10 1 Continuous Dataflow over the Serial Interface 21 Figure 12 1System Installation us 222 0 ies cone ooo e ee ua cie ee 38 Figure 12 2 System Installation Coil Frame with option Removable Bars 39 Figure 15 1 Example of a Matching Box r 53 Figure 15 2 Resonance Tuning Adapter eiecti 53 Figure 15 3 Software Angle Meter NT Enhanced Remote Control 54 Figure 15 4 Enhanced Remote Control Warning Hint 54 Figure 15 5 Enhanced Remote Control Set the nominal voltag
44. cture of Received Bytes The upper three Bits MSBs of each received byte of a Remote Control Function indicate the usage of the Byte the lower five Bits contain the specific data orev 0 XXXXX FunctionByte XXXXXX denotes the Function O 1 O XXXXX DataByte1 XXXXX contains Data used by each function O 1 1 XXXXX DataByte2 XXXXX contains Data used only by certain functions 1 0 O XXXXX DataByte3 XXXXX contains Data used only by certain functions 11 0 1 XXXXX DataByte4 XXXXX contains Data used only by certain functions 1 1 0 XXXXX ControlByte XXXXX contains B5 B1 2 XOR 11111 of the FunctionByte 1 1 1 XYYYY TerminatorByte X contains BO XOR 1 of the FunctionByte YYYY contains B3 B0 XOR 1111 of DataByte1 Table 10 3 Structure of received bytes 10 2 2 Structure of Received Data Packets FunctionByte DataByte1 DataByte2 DataByte3 DataByte4 ControlByte TerminatorByte Note that DataByte2 DataByte4 are used only by certain functions Unused DataBytes are not transmitted within the concerning data packet Example To set the Power Up Mode of the Detector Module to Last State transmit this data packet FunctionByte DataByte1 ControlByte TerminatorByte 00001000 01000001 11011011 11111110 Angle Meter NT User Manual page 27 10 2 3 Remote Control Functions Overview
45. d to saturated output voltages The user has to avoid this by using appropriate settings for the fixed gain values Please note that inappropriate settings of the offset correction values and the gain correction values may also saturate the DACs Angle Meter NT User Manual page 46 Example 1 a is the angular orientation of the search coil in the horizontal plane B is the angular orientation of the search coil in the vertical plane The setting for the Output Swing is 5 V The setting for the fixed gain value is correct a B Induced search coil voltage Vector Lengths Output Voltage fi 36045 Vf1 4 506 V 0 0 f2 32 Vf2 0 004 V f3 34 Vf3 0 004 V f1 36 Vf1 0 005 V 90 0 f2 36051 Vf2 4 506 V f3 33 Vf3 0 004 V fi 18023 Vf1 2 253 V 45 45 f2 18025 Vf2 2 253 V f3 25491 Vf3 3 186 V Table 14 4 Output Mode Example 1 The setting for the fixed gain value is optimal in this example The output voltages do not reach the full range of the output swing by which some dynamic range of the DACs remains reserved This is recommended in order to handle position offsets of the search coil in a certain range and to prevent saturation caused by electrical drift effects Example 2 a is the angular orientation of the search coil in the horizontal plane B is the angular orientation of the search coil in the vertical plane The setting for the Output Swing
46. duced search coil voltage Magnetic Field fx Field Col X 4 E D 2 Search coil Vect_y iL lt T Oo l E Vect x z o I I I I gt gt P ile ss Gee ar AIETEN NONU REM o o STAT MS PE E a eee si Oo D I I I I I I iL iL 2 25 a5 85 a0 100 TET Field Coil X Y 0 80 256 96 120 Frequency kHz Figure 2 1 Measuring Principle The correlation between the angular orientation of the search coil in the external magnetic field and the induced voltage is apparent if we look at the portions of Vx and Vy in the search coil signal These portions correlate with the lengths of the vectors Vect_x and Vect_y which are used to detect the angular orientation a of the search coil Conventional phase locked amplitude detection systems use analog electronics to capture the portions of Vx and Vy in the search coil signal by demodulating the search coil signal with respect to the magnetic field directions This may cause noise phase and drift problems and requires relatively complex adjustments by the user External A D converters are required in order to obtain the angular orientation of the search coil which increases the total system costs The Angle Meter NT uses an other more reliable measuring principle The spectral frequency components of the search coil voltage are analyzed by computing the Fast Fourier Transformation FFT of the digitized search coil sig
47. e measuring data in the format of the currently selected output mode over the serial interface Note that no data will be transmitted during the menu is activated or during the execution time of an eventually called Remote Control Function The format of the transmitted data depends on the currently selected output mode Angular Data Vector Length or Vector Angle see chapter 14 5 5 Output Mode for additional information Continuous data flow Output Mode Angular Data Processing Ch1 gt Ch4 Angular Data Angular Data Angular Data Angular Data Angular Data Angular Data Channel 1 Channel 2 Channel 3 Channel 4 Channel 1 Channel 2 N lt Figure 10 1 Continuous Dataflow over the Serial Interface The time t depends on the selected output mode and the selected processing mode Output Mode Processing Mode Outputted measuring data t Data rate Angular Data Ch12Ch1 Angles alpha and beta of Ch1 only 500 us 2 kHz Angular Data Ch1 gt Ch2 Angles alpha and beta of Ch1 and Ch2 ims 1 kHz Angular Data Ch1 gt Ch4 Angles alpha and beta of all channels 2ms 500 Hz Vector Length Ch12Ch1 Signed vector lengths of Ch1 only 1 ms 1 kHz Vector Length Ch1 gt Ch2 Signed vector lengths of Ch1 and Ch2 2ms 500 Hz Vector Length Ch1 gt Ch4 Signed vector lengths of all channels 4ms 250 Hz Vector Angle Ch12Ch1 Signed vector angles of Ch1 only 1 ms 1 kHz Vector Angle Ch1 g
48. e minimal possible value of the currently selected output swing at all analog outputs and 0 as digital data in the format Angular Data over the serial interface 3 Mid Output The Detector Module outputs 0 Volt at all analog outputs and 2048 as digital data in the format Angular Data over the serial interface 4 Max Output The Detector Module outputs the maximal possible value of the currently selected output swing at all analog outputs and 4095 as digital data in the format Angular Data over the serial interface 5 Ramp Output The Detector Module outputs a ramp from the minimal to the maximal possible value of the currently selected output swing at all analog outputs and 0 4095 incremented by one as digital data in the format Angular Data over the serial interface Table 9 1 Menu Settings Angle Meter NT User Manual page 20 10 Serial Interface The bidirectional serial interface RS 232 of each Detector Module transmits the measuring data and is capable to change the settings of the parameters of the Detector Module by the use of Remote Control Functions The delivered software for Windows 9x 2000 XP may be used in conjunction with the serial interface Interface settings 115200 bps 8 data bits 1 stop bit no parity Handshake mode Hardware RTS CTS Pinout see chapter 18 Pinouts 10 1 Transmitted Data During normal operation the Detector Module continuously transmits th
49. e new setting push the knob for a time shorter than one second to discard the new setting and restore the old setting of the actual parameter push the knob longer than one second To exit the menu push the knob longer than one second instead of selecting a parameter 9 3 1 How to use the Menu Example To change the setting of the output voltage swing follow these steps 1 During normal operation push the knob longer than one second in order to activate the menu gt 1sec 2 Once the menu is activated turn the knob until the parameter H Output Swing is displayed Note that the blinking cursor appears in the first line of the LCD indicating that the menu is in the mode which scrolls trough the parameters the actual setting of the parameter is displayed in the second line of the LCD O O 3 To change the setting of the output voltage swing push the knob for a time shorter than one second The cursor moves down to the second line of the LCD indicating that the setting of the parameter now can be changed lt 1 sec Angle Meter NT User Manual page 13 Notes 4 To change the actual setting of the output voltage swing turn the knob until the desired new setting is displayed in the second line of the LCD O O To accept the new setting push the knob for a time shorter than one second To discard the new setting and res
50. easuring channels If your system consist only of one Detector Module i e four measuring channels the cabling of the right Detector Module is omitted Turn off the main switch at the rear panel of the Angle Meter NT before wiring the system Check the indicated value for the line voltage on the label at the rear of the base unit 115 VAC or 230 VAC The Angle Meter NT may be installed and used by qualified research personnel only If the coil frame is installed on a turntable it is strongly recommended to place the preamplifier s also on it to minimize the lengths of the connection wires between the search coil s and the Preamplifier See chapter 13 Slip Ring Wiring for additional information if required Note Use only the delivered original cables Should you need extension cables please contact Primelec B i Analog Data Personal Computer Angle Meter NT Base Unit P mes eine ___ Slip Ring Contacts if required Coil Frame A Search Coil s f J A lt Preamplifier s Matching Box Figure 12 1 System Installation Angle Meter NT User Manual page 38 Analog Data Personal Computer Recorder RS 232 Interface Angle Meter NT Base Unit Slip Ring Contacts if required Coil Frame Search Coil s Power Supply Preamplifier s Matching Box Figure 12 2 System Installation Coil Frame with option Removable Bars Once
51. ects More precisely the digitally outputted vector lengths may be checked they must be below 40000 independently of the angular orientation of the search coil s Vector Angle The output signals sVectAngX sVectAngY and sVectAngZ represent the phase angles phi of the three frequencies f1 80 kHz X axis f2 96 kHz Y axis and f3 120 kHz Z axis of the induced voltage in the search coil where phi lies in the range from pi to pi Internal phi is used in order to determine the sign of the signed vector lengths Under normal circumstances this output mode will not be used However it may be helpful during trouble shooting for example if you are manufacturing your own coil frame An exactly tuned system normally outputs values for phi 7 pi 2 or phi 7 pi 2 depending in the actual polarity of the search coil The output signals are simultaneously available in two forms as analog output voltages and as digital data over the serial interface where their update rate depends on the actual processing mode see below Processing Mode The analog output voltages are scaled to the range from pi to pi the digital data is multiplied by 2600 for transmission 14 5 6 Output Swing The range of the output swing of the analog outputs is selectable to match the output voltages to the input voltage range of the connected external device for example a data recorder To achieve an optimal signal to noise ratio it is suggested to make ful
52. edd pieius vw osz 1 pieius Uld jeyidureeud vuosz zi ai pepiaus ve omy L Uld Joydel vw osz ol di pepieus wz omy a eC EL Uld Jeyijdureejg dl p pl us YZ DMV I vw OSZ 84 l dl p pl us pz DMV l ZL Uld Jodeci vu osz z l di p pl luS sz OMY S Uld dwed vu osz 94 l di p pl luS sz OMY 8 Uld 1eyidureeud dL p pl uS YZ SN V I vw osz SL l dL Dp pl uS YZ DMV l E RE SSS gx gd X G Uld segidueeug dipepieus pzomv vuos2 di pepes wz omy di peplus rz owv vwosz er a p peus ve omy 9 Uld J lJlIduue Jd y Uld Jeyijdureeug Uld Jeyijdureeug Uld Aded E Uld Jeyidueeud ZL Uld JeyijduueeJd S Uld JeyijduueeJd 8 Uld JeyidureeJg G Uld Joyl dweeld 9 Uld Jeyi dueeug QNS fee ENS i OO9V XIJ se W 2 leo LY XAN OV XNW EE EA IN e NM NM Lu IN NN 6 uld xog Butuojeiw pieius vu osz 6 pieius gud xogDuuxew dipepius zzomv f vwoos e aiPepeus zzowv 1ud xog Buuxew arPePeus zeowv wwoos z di pepisus zzowv Uld xog Butuojeiw pieius vuosz 9 pieius uld xog Buiyowew dLPepes zzowv vwoo9s arPepeus zzomv cud xogBuuxew dipepius zzomv wwoos r a p peus zzowv 9 Uld xog Butuojeiw pl us yw osz pieius l G Uld xog buiyjem dipepius zzomv vwoos z
53. erformance the search coil signals of the used measuring channels have to be in a certain voltage range If the preamplifier is operated in the AGC mode this is automatically ensured as long as the parameters of the used search coils are within the technical specification and the field signals are not attenuated If the preamplifier is operated in the fixed gain mode the signal amplitudes depend on the effective area of the search coils their angular orientation and position in the field the attenuation of the field signals and the settings of the fixed gain values The four bicolor LEDs at the front panel of the Detector Module are used as level indicators to monitor the signal amplitudes of each measuring channel LED Ch n off The signal amplitude from measuring channel n is too small therefore the signal to noise ratio of this channel s output data may be decreased Increase the fixed gain value for this channel and or decrease the attenuation of the field signals in order to achieve an optimal s n ratio LED Ch n green The signal amplitude from measuring channel n is within the desired voltage range Reliable output data with an optimal signal to noise ratio is ensured LED Ch n red The signal amplitude from measuring channel n is too high the ADC may be overdriven and the output data may be corrupted Decrease the fixed gain value for this channel and or increase the attenuation of the field signals until the LED lights alw
54. erved These bits are reserved for future use 10 1 1 2 DataByte COCOA BID X X X X X X X BID Byte Identifier 0 B7 0 indicates a DataByte The byte contains data in the remaining bits B6 BO according to the lastly transmitted PacketInfoByte X Data B6 B0 contain measuring data or parameter data according to the lastly transmitted PacketinfoByte i e depending on the type of the data packet Note that the Bit 6 of certain DataBytes is a sign bit where sign 0 indicates positive and sign 1 indicates negative values Angle Meter NT User Manual page 23 10 1 2 Structure of Transmitted Data Packets The dataflow consists of sequentially transmitted data packets Each transmitted data packet begins with a PacketlnfoByte immediately followed by one or several DataBytes where the number of DataBytes within a packet depends on the type of the transmitted data packet 10 1 2 1 Angular Data Based on the FFT calculations the DSP executes the trigonometric computations to determine the angular displacement alpha horizontal plane and beta vertical plane of the search coil relative to the system s reference frame coil frame The angular data is scaled from 0 to 4095 for the angle alpha representing the range from 0 to 359 91 and from 1024 to 3072 for the angle beta representing the range from 90 to 90 The angular data is transmitted in data packets consisting of one Packet nfoByte plus four DataBytes pe
55. es of the field signals 55 Figure 16 1 Block Diagram System Overview sse 56 Figure 16 2 Block Diagram Preamplifier Overview a 57 Figure 16 3 Block Diagram Preamplifier Gain Mode AGC 57 Figure 16 4 Block Diagram Preamplifier Gain Mode Fixed 57 Figure 17 1 Flowchart DSP Main Task Measuring Cycle 58 List of Tables Table 2 1 Correlation Examples ener nn nere nennen 7 Table 9 1 Menu Settings e ni eL EK sagey XE Feb dU REX 4 eR REB eR NR 20 Table 10 1 Update rate of the measuring data over the Serial Interface 21 Table 10 2 Structure of transmitted bytes ras 22 Table 10 3 Structure of received bytes ona rep eret Dente He gae ee ne 27 Table 10 4 Remote Control Functions Overview sssseeen 29 Table 10 5 Remote Control Function Meaning of the DataByte s 36 Table 11 1 Update rate of the analog outputs a ene 37 Table 193 1 Slip Ring Wiring ereere egini b Oe ee 40 Table 14 1 Gain Correction Example I 42 Table 14 2 Offset Correction Exa
56. es the offset correction values for each measuring channel automatically See chapters 9 3 Menu or 10 2 3 Remote Control Functions for additional info All offset correction values are set to zero at the factory To change the values use the concerning Remote Control Function over the serial interface After the valid offset correction values have been set and the offset correction was enabled the offset on the output signals is minimized Note that all offset correction values are permanently stored non volatile in the Detector Module 14 5 Choosing the best suited settings for your application 14 5 1 Field Signals The field signals may be attenuated for example if very large search coils are used The field signals may be turned off completely for example if it is meanwhile required to execute other measurements without the influence caused by the magnetic field Under normal conditions the field signals should remain to 100 of their nominal values 14 5 2 Gain Mode Both gain modes of the Angle Meter NT AGC or Fixed have their pros and limitations AGC Fixed Easy system handling The AGC allows the use of different search Full system functionality Both the gain correction and the offset coils without the need of any system recali bration by the user correction are fully applicable Under difficult measuring conditions the use of these correction functions can improve the precision of the outpu
57. escription A Display Illum 1 Off The backlight of the LCD is turned off 2 Dark The backlight of the LCD is dark 3 Medium The backlight of the LCD is medium 4 Bright The backlight of the LCD is bright B Field Signals 0 Add On Module The intensity of the field signals can not be changed because of this is the Add On Detector Module Use the Main Detector Module if you want to change the setting of this parameter Off The field signals are turned off The field signals are attenuated to 20 96 of their nominal values The field signals are attenuated to 40 of their nominal values The field signals are attenuated to 60 of their nominal values The field signals are attenuated to 80 of their nominal values 100 The field signals are at 100 of their nominal values C Gain Corr H Disabled The gain correction is disabled not active Enabled The gain correction is enabled active and the output data of all four measuring channels is calculated on the basis of the individual gain correction values for each frequency of each channel This means that the signed vector lengths from the FFT calculations are multiplied by the concerning gain correction values If the search coil is placed outside the 3D centre of the magnetic field this allows the correction of the magnetic field inhomogeneity in a certain range See also chapter 14 3 Use of the gain correction Note that
58. f Transmitted Bytes 2000 L 22 10 1 2 Structure of Transmitted Data Packets 24 10 2 Received Data e et IHR n de a RR ER RENE AY RE e ER E a 27 10 2 1 Structure of Received Bytes L 27 10 2 2 Structure of Received Data Packets ceteri nnns 27 10 2 3 Remote Control Functions Overview ssessee 28 10 2 4 Remote Control Functions Meaning of the DataByte s 29 11 Analog OUT DUIS ccn iain ocu nixa Ore us Dep e SS ai P PEL ERE DEVE EUR DE MEE au sayas 37 12 System Installation iron reote ente tn pereo ino ene ca nta naia karanana aasma a Rasa ercOEO 38 13 Slip Ring Wirinig iuieeiiine ecco itin cuc ocius de ak ge acu c anu en zo aiu acu c akin en o s iu anuo SR na an ER ELER CEDE E E ERED S 40 14 System Optimization l eer ttr etre t po ei u ein ne eee 41 14 1 Optimizing the Magnetic Field Homogeneity 1 41 14 2 Optimizing the Measuring Signal Quality a 41 14 3 Use of the Gain Correction a 42 14 4 Use of the Offset Correction I 43 14 5 Choosing the best suited settings for your application 44 14 5 1 Field Sidghal s 6 e te dE oon E cc b 44 14 9
59. ffers both standardized as well as user specified coil frames in various colors arranged as a cube with an edge length in the range from 30 cm to 70 cm Due to the monocoque construction the restriction of the visual field is minimal Our coil frame can be de and remounted which may be helpful during the building of user specified setups Caution If the coil frame has Removable Bars optional do not remove or insert the Removable Bars while the system is operating Turn off the power of the Angle Meter NT before handling the bars If the coil frame is mounted on a turntable seven slip ring contacts are required for wiring See chapter 12 System Installation and 13 Slip Ring Wiring for additional information An optimal quality of the magnetic field is fundamental for reliable measurements Mismatched field intensities and extensive phase errors will lead to an inhomogeneous resulting field which causes invalid results Irradiation of external devices and metallic materials in or near to the field may be critical because of field distortion To avoid problems read chapter 14 System Optimization of this Manual See also chapter 15 Tuning the system with a new coil frame for additional information if the user plans to fabricate a specific coil frame AN Angle Meter NT User Manual page 9 7 Search Coils A miniature search coil for example 80 turns with a diameter of 2 mm which is placed at the 3D
60. gth and Vector Angle K Setups 1 Recall Mem1 The settings of all parameters including the values for fixed gain gain correction and offset correction are recalled from Memory 1 of the Detector Module 2 Save Mem1 The actual settings of all parameters including the values for fixed gain gain correction and offset correction are saved to Memory 1 of the Detector Module 3 Recall Mem 2 The settings of all parameters including the values for fixed gain gain correction and offset correction are recalled from Memory 2 of the Detector Module 4 Save Mem2 The actual settings of all parameters including the values for fixed gain gain correction and offset correction are saved to Memory 2 of the Detector Module Angle Meter NT User Manual page 19 Parameter Setting Description 5 Recall Fact All parameters of the concerning Detector Module will be reset to their factory settings which are e Display Illumination Medium e Field Signals 100 e Gain Correction Disabled e Gain Mode AGC e Offset Correction Disabled e Output Filter Disabled e Output Mode Angular Data e Output Swing 9 Volt e Power On Mode Default e Processing Mode Ch1 gt Ch4 1 kHz e Gain Correction Values 1 0 e Fixed Gain Values 63 e Offset Correction Values 0 L Test Signals I Off No test signals are active 2 Min Output The Detector Module outputs th
61. he range of the voltage swing of the analog outputs is set to 5 Volt Data1 3 The range of the voltage swing of the analog outputs is set to 9 Volt Data1 4 The range of the voltage swing of the analog outputs is set to 10 Volt Set Power On Mode Data1 0 The parameters of the concerning Detector Module will be reset at each power up of the Angle Meter NT to their default values which are e Display Illumination Medium e Field Signals 100 e Gain Correction Disabled e Gain Mode AGC e Offset Correction Disabled e Output Filter Disabled e Output Mode Angular Data e Output Swing 9 Volt e Processing Ch1 gt Ch4 1 kHz Data1 1 The settings of the parameters of the concerning Detector Module will be recalled at each power up of the Angle Meter NT to their state during the last power down of the Angle Meter NT Set Processing Data1 0 The Detector Module processes only one measuring channel Channel 1 The update rate of the analog outputs is 4 kHz for all output modes where the update rate of the digital data over the serial interface is 2 kHz for the output mode Angular Data and 1 kHz for the output modes Vector Length and Vector Angle Data1 1 The Detector Module processes only two measuring channels Channel 1 and Channel 2 The update rate of the analog outputs is 2 kHz for all output modes where the update rate of the digital data over the serial
62. his is the picked up stray signal which has to be eliminated to achieve optimal output data Then the Auto Tuning can be started The system performs a routine which detects the present input signal at each channel which is in fact the picked up stray signal Therefore the signed vector lengths from the FFT calculations during the routine are the offset correction values for the later use The execution time of the routine is approximately 2 seconds After the routine has performed the offset correction of the Module is enabled and the detected offset correction values are used See also above Enabled offset correction F Output Filter 1 Disabled The digital filter is disabled not active 2 Enabled The digital filter is enabled active and the output signals of all four measuring channels are feed trough the digital filter This means that the signed vector lengths from the FFT calculations are feed trough a digital IIR Filter e order Butterworth low pass filter implemented on the DSP with a cutoff frequency of one eighth of the output data rate of the analog outputs If there are noisy measurement conditions the use of the output filter may be helpful G Output Mode 1 Angular Data Based on the FFT calculations the DSP executes the trigonometric computations to determine the angles alpha horizontal plane and beta vertical plane between the angular orientation of the search coils a
63. interface is 1 kHz for the output mode Angular Data and 500 Hz for the output modes Vector Length and Vector Angle Data1 2 The Detector Module processes all four measuring channels Channel 1 to Channel 4 The update rate of the analog outputs is 1 kHz for all output modes where the update rate of the digital data over the serial interface is 500 Hz for the output mode Angular Data and 250 Hz for the output modes Vector Length and Vector Angle Set Setups Data1 0 The settings of all parameters including the values for fixed gain gain correction and offset correction are recalled from Memory 1 of the Detector Module 10 Data1 1 The actual settings of all parameters including the values for fixed gain gain correction and offset correction are saved to Memory 1 of the Detector Module 10 Data1 2 The settings of all parameters including the values for fixed gain gain correction and offset correction are recalled from Memory 2 of the Detector Module Angle Meter NT User Manual page 33 Description F Data Description 10 Data1 3 The actual settings of all parameters including the values for fixed gain gain correction and offset correction are saved to Memory 2 of the Detector Module 10 Data1 4 All parameters of the concerning Detector Module will be reset to their factory settings which are e Display lllumination Med
64. irregular distortion of the magnetic field which will lead to noisy output data e Avoid large metallic parts iron aluminum copper reinforced concrete etc near to the coil frame Those may cause an asymmetrical damping of the magnetic fields which will lead to nonlinear output data e Do not disconnect the coil frame from the Matching Box during the field signals are turned on This will lead to a heavy capacitive load which may overheat and destroy the power amplifiers of the Generator Module 14 2 Optimizing the Measuring Signal Quality A good quality of the input signal is very important Follow these hints to achieve best results e The effective area of the used search coils should be as large as allowed by the application in order to achieve an optimal signal to noise ratio Make sure that the parameters of the used search coils are within the values specified in the technical data e Twist the two connection wires of the search coils extremely careful and hold their length as short as possible in order to minimize offsets on the output signals due to stray pick up on the search coil signal Angle Meter NT User Manual page 41 e Place the search coils as precisely as possible in the 3D centre of the coil frame in order to achieve optimal output data in terms of system linearity e Place the preamplifier least 1 m from the coil frame to minimize irradiation on the measuring signal If not possible an additional shielding of the
65. itudes of the field signals where they are directly proportional to the relative values The labels below indicate the actual settings of these relative values for the nominal voltages of the field signals fl 80 kHz f2 36 kHz f3 120 kHz 1845 1830 T860 Read the relative values from the Angle Meter NT Change the settings of the nominal field voltages eee m Figure 15 3 Software Angle Meter NT Enhanced Remote Control Caution You are about to change the nominal voltages of the field signals which generate the magnetic field of the Angle Meter NT The nominal voltages of the field signals are adjusted at the factory to ensure the specified magnetic flux density and an optimal field homogeneity at the 3D centre of the field coils Therefore the settings of the nominal field voltages should not be changed under normal circumstances Refer handling to qualified personnel only Please read the technical manual of the Angle Meter NT before you continue Don t show this message again cive Cancel i Wasa x Figure 15 4 Enhanced Remote Control Warning Hint Angle Meter NT User Manual page 54 angle Meter NT Set the nominal voltages of the field signals Figure 15 5 Enhanced Remote Control Set the nominal voltages of the field signals Angle Meter NT User Manual page 55 16 Block Diagrams eoepuejul c C SH s ndjno Bojeuy A
66. ium e Field Signals 100 e Gain Correction Disabled e Gain Mode AGC e Offset Correction Disabled e Output Filter Disabled e Output Mode Angular Data e Output Swing 9 Volt e Power On Mode Default e Processing Mode Ch1 gt Ch4 1 kHz e Gain Correction Values 1 0 e Fixed Gain Values 63 e Offset Correction Values 0 Set Test Signals 11 Data1 0 No test signals are active 11 Data1 1 The Detector Module outputs the minimal possible value of the currently selected output swing at all analog outputs and 0 as digital data in the format Angular Data over the serial interface 11 Data1 2 The Detector Module outputs O Volt at all analog outputs and 2048 as digital data in the format Angular Data over the serial interface 11 Data1 3 The Detector Module outputs the maximal possible value of the currently selected output swing at all analog outputs and 4095 as digital data in the format Angular Data over the serial interface 11 Data1 4 The Detector Module outputs a ramp from the minimal to the maximal possible value of the currently selected output swing at all analog outputs and 0 4095 incremented by one as digital data in the format Angular Data over the serial interface Angle Meter NT User Manual page 34 Description F Data Description Read Parameter 15 Data1 1 Causes the Detector Module to transmit the actual settings of the general parameter
67. l of the following conditions are true e Vector length for Ch1 f1 sVectLenX has a value as close to zero as achievable e Vector length for Ch1 f2 sVectLenY has a value as close to zero as achievable e Vector length for Ch1 f3 sVectLenZ has the maximal achievable value Do not move the position but vary only the angular orientation of the search coil Fix the search coil once it has an angular orientation such that these conditions are true The search coil should now have an orthogonal orientation relative to the coil frame axis Z and a parallel orientation relative to the coil frame axes X and Y Use the program Angle Meter NT Enhanced Remote Control to increase or decrease the relative value of the nominal field voltage U f3 120 kHz Z axis until the value for Ch1 f3 is equal to sVectLenX MAX see step 5 Table 15 1 Field Voltage Fine Tuning Step by Step Angle Meter NT User Manual page 52 15 4 Figures TRIO Core 36x23x15 Philips 3C11 EPCOS N30 PwX STIJ4 gt E gt x 730 a Cio cu ca cia 80 kHz a a D D e Coil frame arrangement 3 CwX STIJS gt M ENEP E 7
68. l use of the available input voltage range of the connected device by choosing the appropriate output swing Angle Meter NT User Manual page 48 14 5 7 Processing Mode In order to increase the update rate of the output signals measuring channels can be limited the number of the processed Processing Ch1 gt Ch1 Processing Ch1 gt Ch2 Processing Ch1 gt Ch4 The Detector Module processes only one measuring channel channel 1 The update rate of the analog outputs is 4 kHz for all output modes The update rate of the digital data over the serial interface is 2 kHz for the output mode Angular Data and 1 kHz for the output modes Vector Length and Vector Angle The Detector Module processes only two measuring channels channel 1 and channel 2 The update rate of the analog outputs is 2 kHz for all output modes The update rate of the digital data over the serial interface is 1 kHz for the output mode Angular Data and 500 Hz for the output modes Vector Length and Vector Angle The Detector Module processes all four measuring channels channel 1 to channel 4 The update rate of the analog outputs is 1 kHz for all output modes The update rate of the digital data over the serial interface is 500 Hz for the output mode Angular Data and 250 Hz for the output modes Vector Length and Vector Angle Table 14 6 Processing Mode Description The table below indicates the
69. ld Signals 100 e Gain Correction Disabled e Gain Mode AGC e Offset Correction Disabled e Output Filter Disabled e Output Mode Angular Data e Output Swing 9 Volt e Processing Ch1 gt Ch4 1 kHz 2 Last State The settings of the parameters of the concerning Detector Module will be recalled at each power up of the Angle Meter NT to their state during the last power down of the Angle Meter NT J Processing 1 Chl gt Chl The Detector Module processes only one measuring channel Channel 1 The update rate of the analog outputs is 4 kHz for all output modes where the update rate of the digital data over the serial interface is 2 kHz for the output mode Angular Data and 1 kHz for the output modes Vector Length and Vector Angle 2 Chl gt Ch2 The Detector Module processes only two measuring channels Channel 1 and Channel 2 The update rate of the analog outputs is 2 kHz for all output modes where the update rate of the digital data over the serial interface is 1 kHz for the output mode Angular Data and 500 Hz for the output modes Vector Length and Vector Angle 3 Chl gt Ch4 The Detector Module processes all four measuring channels Channel 1 to Channel 4 The update rate of the analog outputs is 1 kHz for all output modes where the update rate of the digital data over the serial interface is 500 Hz for the output mode Angular Data and 250 Hz for the output modes Vector Len
70. mple 43 Table 14 3 Gain Mode pros and limitations 44 Table 14 4 Output Mode Exarniplo T ia ior mtr ore tans erro Fever vl erro n Gare rk eG or Ra 47 Table 14 5 Output Mode Example 2 sess nnne 48 Table 14 6 Processing Mode Description 49 Table 14 7 Processing Mode Suggestloris einer teer ed cse Rd eeteeens 49 Table 15 1 Field Voltage Fine Tuning Step by Step 52 Angle Meter NT User Manual page 3 Angle Meter NT User Manual page 4 1 Safety Information read this first N The coil frames of the Angle Meter NT generate relatively strong magnetic fields which can lead to injury to health Capacitive and inductive coupling onto organisms and devices sensitive in this regard must be considered The signals applied to the coil frames may have hazardous voltage levels An inappropriate application touching the conductors or the coil frames capacitive and or inductive couplings etc can come for injuries to health The inputs of the preamplifiers are not off ground i e the search coils are not galvanic isolated from ground Depending on the measuring environment and application this may be a possible risk for injuries to health and should be considered There are country specific
71. n Fix ChN 28 31 Data1 Upper Data2 Lower Sets the fixed gain value for channel N The allowed range of the fixed gain values is between 0 and 255 For a detailed description of the usage of the fixed gain values see Set Gain Mode above Set Offs Corr 32 Data1 MostUpper Sets the offset correction value for channel N frequency ChN fM Data2 Upper M The allowed range of the offset correction values is 43 Data3 Lower between 100000 and 100000 Note that the MSB of Data4 MostLower Data 1 acts as a sign bit where sign 0 indicates positive and sign 1 indicates negative values For a detailed description of the usage of the offset correction values see Set Offset Corr above Table 10 5 Remote Control Function Meaning of the DataByte s Note The range of data not explicitly listed in the table above is reserved for factory used settings or future use respectively Angle Meter NT User Manual page 36 11 Analog Outputs The analog outputs of each Detector Module are implemented by twelve 12 Bit digital to analog converters DACs Depending on the currently selected output mode and processing mode the DACs are continuously updated with the results of the DSP s computations Note that the analog outputs are not updated during the menu is activated or during the execution time of an eventually called Remote Control Function Output Mode Proce
72. nal which results directly the signed vector lengths of the vectors Vect_x and Vect_y The use of a powerful digital signal processor DSP allows to compute the FFT and the trigonometric calculations in real time This approach offers various advantages compared to conventional systems and eliminates most of the weaknesses described above Angle Meter NT User Manual page 6 The figures below show again some examples to illustrate the correlation between the angular orientation of the search coil in the external magnetic field the resulting induced search coil voltage and the computed signed vector lengths from the FFT where o is the angular orientation of the search coil in the horizontal plane B is the angular orientation of the search coil in the vertical plane the magnetic field frequency f1 in the X axis is 80 kHz axis is 96 kHz the magnetic field frequency f2 in the Y the magnetic field frequency f3 in the Z axis is 120 kHz and the signed vector lengths are scaled to 1 for better clarity Signed vector lengths 256 En 0 Frequency kHz f 4 256 Frequency kHz 256 LIII 0 Frequency kHz f 4 256 120 80 96 Frequency kHz f 4 256 Frequency kHz 256 Frequency kHz Induced search coil voltage T I z I Moser I
73. nals are picked up The search coil signal is influenced by a picked up stray signal caused by inaccurately twisted connection wires sVectLenX 15030 sVectLenY 20220 sVectLenZ 29854 The search coil is 2 completely shielded the Fi cep ase I L 4 remaining measuring signal ga NS A Pie a sVectLenY 1838 consists only of the picked up i E AS sVectLenZ 3895 stray signal t us PS sVectLenX 3300 Table 14 2 Offset Correction Example To determine the offset correction values place the search coils into their position in the field and shield them completely such that they can not pick up a field signal Therefore under optimal conditions there is now no signal from the search coil If there is a remaining signal this is the picked up stray signal which has to be subtracted in order to eliminate offsets on the output signals The output mode Vector Length delivers the signed vector lengths from the FFT calculations where the offset correction should be disabled at this time to avoid false Angle Meter NT User Manual page 43 results due to eventually existing invalid offset correction values The offset correction values for future use are now represented by the actual signed vector lengths Note that the Angle Meter NT offers an Auto Tuning function which captures the remaining measuring signals of the completely shielded search coils and therefore determin
74. nd the coil frame The results are available as analog outputs and as digital data over the serial interface The voltage swing of the analog outputs is adjustable see H Output Swing the progression is described in the technical data See also the pinout of the connector with the analog outputs The format of the digital data is described in chapter 10 1 Transmitted Data For information concerning the processing speed and the resulting update rate of the outputs see J Processing below Angle Meter NT User Manual page 17 Parameter Setting Description 2 Vector Length The signed vector lengths for f1 X axis f2 Y axis and f3 Z axis from the FFT calculations are available as analog outputs and as digital data over the serial interface The voltage swing of the analog outputs is adjustable see H Output Swing If the gain mode is set to AGC the output voltages are always scaled to fit the dominant vector in order to make full use of the available dynamic range If the gain mode is set to Fixed the scaling of the output voltages is fixed The scaling is based on a vector length of 40000 This may be useful to subtract offsets externally For details see chapter 14 5 Choosing the best suited settings for your application See also the pinout of the connector with the analog outputs The format of the digital data is described in chapter 10 1 Transmitted Data For information conce
75. netic flux density If the flux density is reduced by attenuating the field signals to 20 96 of their nominal values the allowed effective area may be up to 160 cm The preamplifier is placed in a separate box and processes four search coils It can be set to AGC or fixed gain by the user See chapter 18 Pinouts Approx 100 x 40 x 200 mm wxh x d Approx 330 g The output format of the measuring data can be selected by the user linear angular data for the horizontal and the vertical plane signed vector lengths or signed vector angles for X Y and Z 360 in the horizontal plane gt 80 in the vertical plane 0 05 6 order digital Butterworth low pass filter with a cutoff frequency of one eighth of the output data rate of the analog outputs The filter may be enabled or disabled by the user lt 0 1 during warm up see also diagram below lt 0 5 over 360 see also diagram below lt 0 3 over 80 see also diagram below 0 2 in the specified range see also diagrams below lt 0 09 pp see also diagrams below 4 kHz 2 kHz or 1 kHz depending on the number of processed measuring channels selectable by the user 2 5 V 4 5 V 5 V 9 V 10 V selectable by the user 51 ohm typical See chapter 18 Pinouts Angle Meter NT User Manual page 61 Diagrams
76. ngle Meter NT User Manual page 67 Distribution of angular noise Notes 1 to 4 amp 6 amp 8 Angular noise on Ch 1 Alpha Beta 180 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 60 60 40 40 20 20 0 0 0 09 40 00 0 09 0 09 0 00 40 09 Angular noise on Ch 1 Alpha Beta 170 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 0 60 60 40 40 20 20 0 8 3 8 0 F F 0 09 0 00 0 09 Angular noise on Ch 1 Alpha Beta 160 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 60 60 40 40 20 20 0 0 0 18 0 09 0 00 0 09 0 09 0 00 0 09 Angle Meter NT User Manual page 68 Distribution of angular noise cont Notes 1 to 4 amp 6 amp 8 Angular noise on Ch 1 Alpha Beta 150 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 o 60 60 40 40 20 20 0 8 8 8 0 7 9 9 0 09 40 00 0 09 Angular noise on Ch 1 Alpha Beta 140 Angular noise on Ch 1 Beta Alpha 270 100 100 80 80 o 60 60 40 40 20 20 0 8 3 8 0 9 0 48 0 09 0 00 0 09 Angular noise on Ch 1 Alpha Beta 130 Angular noise on Ch 1 Beta Alpha 270
77. nnel channel 1 is processed 2 Only two measuring channels channel 1 and channel 2 are processed 4 Allfour measuring channels channel 1 to channel 4 are processed GM Gain Mode The actual gain mode for the amplification of the search coil signals A AGC the automatic gain control of the preamplifier is enabled for all four measuring channels F Fixed gain the individual gain of the four measuring channels is set to a fixed value OF Output Filter The actual setting of the digital output filter The digital filter is disabled not active The digital filter is enabled active and the output signals of all four measuring channels are feed trough the digital filter OC Offset Correction The actual setting of the offset correction The offset correction is disabled not active The offset correction is enabled active and the output signals of all four measuring channels are calculated on the basis of the individual offset correction values GC Gain Correction The actual setting of the gain correction The gain correction is disabled not active The gain correction is enabled active and the output signals of all four measuring channels are calculated on the basis of the individual gain correction values See chapters 9 3 Menu 10 2 3 Remote Control Functions and 14 5 Choosing the best suited settings for your application for details concerning the used parameters 9 2 LEDs To achieve an optimal system p
78. ogeneous resulting field and therefore may cause inaccurate output data Irradiation of external devices and metallic materials in or near to the field may be critical because of field distortion To avoid problems follow these hints e f you are manufacturing your own coil frames and Matching Boxes do it carefully it will pay Only use first quality components twist all connection wires carefully and minimize contact resistances Adjust the resonance circuits and magnetic field strengths exactly See chapter 15 Tuning the system with a new coil frame for an overview of how to do this e f you own several Angle Meter NTs and coil frames delivered by Primelec please keep in mind that each device is adjusted with the related coil frame Watch the serial numbers of the base units and the coil frames to avoid confusion Do not swap Modules between the base units e f you are using extension cables to connect the Matching Box only use very high quality cables i e shielded twisted pairs for each balanced field signal Keep the cables as short as any possible Improper cabling and inappropriate slip rings may lead to crosstalk between the field signals resulting in nonlinear output data e Avoid third party devices with electrical radiation transmitters computers CRTs electric motors etc near to the coil frame If these radiated frequencies are in the spectrum of the magnetic field frequencies of the Angle Meter NT this may cause an
79. one eighth of the output data rate of the analog outputs If there are noisy measurement conditions the use of the output filter may be helpful Angle Meter NT User Manual page 31 Description F Data Description Set Output Mode Data1 0 Angular Data Based on the FFT calculations the DSP executes the trigonometric computations to determine the angles alpha horizontal plane and beta vertical plane between the angular orientation of the search coils and the coil frame The results are available as analog outputs and as digital data over the serial interface The voltage swing of the analog outputs is adjustable see Set Output Swing the progression is described in the technical data See also the pinout of the connector with the analog outputs The format of the digital data is described in chapter 10 1 Transmitted Data For information concerning the processing speed and the resulting update rate of the outputs see Set Processing below Data1 1 Vector Length The signed vector lengths for f1 X axis f2 Y axis and f3 Z axis from the FFT calculations are available as analog outputs and as digital data over the serial interface The voltage swing of the analog outputs is adjustable see H Output Swing If the gain mode is set to AGC the output voltages are always scaled to fit the dominant vector in order to make full use of the available dynamic range If the gain mode
80. or Module and one or two Detector Modules The main switch at the base unit s back panel disconnects the device from the AC input voltage Figure 4 1 Base unit with the Generator Module and Figure 4 2 Base unit plus Add On Detector Module the Main Detector Module 5 Generator Module The Generator Module generates three digitally synthesized sine wave signals of different frequencies which are amplified by three power amplifiers with balanced outputs field signals These are used for the generation of the magnetic fields The frequencies of the field signals are f1 80 kHz used for the generation of the magnetic field in the X axis f2 96 kHz used for the generation of the magnetic field in the Y axis f3 120 kHz used for the generation of the magnetic field in the Z axis The amplitudes of the field signals are tuned at the factory to achieve the specified flux density and an optimal homogeneity of the magnetic field at the 3D centre of the coil frame The user may attenuate the tuned field signals in steps of 20 96 down to zero This allows to reduce the magnetic field strength for example if extremely large search coils are used or to turn off the magnetic field See also the description of the Detector Module in this Manual The Generator Module also produces an internal synchronization signal which is used by the Detector Modules to synchronize the start of the measurements The
81. pation The data was Note 2 Note 3 Note 4 Note 5 Note 6 Note 7 Note 8 acquired over the serial interface Measuring channel 1 was used where the performance of all measuring channels is identical Settings e Field signals at 100 of their nominal value unless otherwise noted e Gain Correction disabled e Gain Mode AGC e Offset Correction disabled e Output Mode Angular Data Output Filter disabled unless otherwise noted e Output Swing 9 V e Processing Mode Ch1 gt Ch4 Measurement executed with a stepper motor driven search coil under software control Used coil frame formed as a monocoque cube s 700 mm Used search coil with an effective area 10 8 cm2 37mm 1 turn DC Resistance 7 ohm placed at the 3D center of the coil frame Field signals attenuated to 40 of their nominal value i e reduced magnetic flux density Field signals attenuated to 20 of their nominal value i e reduced magnetic flux density Output filter enabled during the measurement Distribution of angular noise based on 5000 continuously acquired samples Angle Meter NT User Manual page 71 20 Personal Notes Angle Meter NT User Manual page 72 Angle Meter NT User Manual page 73 Angle Meter NT User Manual page 74
82. r channel PacketlnfoByte UpperAlpha LowerAlpha UpperBeta LowerBeta PacketlnfoByte See description above DataBytes UpperAlpha UpperBeta fer fs e fe ee o fe D11 D10 DataBytes LowerAlpha LowerBeta fer es os eos 9 0 D6 D5 D4 D3 D2 D1 DO 10 1 2 2 Vector Length The signed vector lengths sVectLenX f1 X axis sVectLenY f2 Y axis and sVectLenZ f3 Z axis from the FFT calculations are transmitted in data packets consisting of one PacketInfoByte plus nine Databytes per channel PacketlnfoByte UpperX MidX LowerX UpperY MidY LowerY UpperZ MidZ LowerZ PacketlnfoByte See description above DataBytes UpperX UpperY UpperZ e eju e e u u Sign D19 D18 D17 D16 D15 D14 Databytes MidX MidY MidZ CCIC D12 D11 D10 Angle Meter NT User Manual page 24 DataBytes LowerX LowerY LowerZ m s gt 0 D6 D5 D4 D3 D2 D1 D0 10 1 2 3 Vector Angle The values for the signed vector angles sVectAngX X axis sVectAngY Y axis and sVectAngZ Z axis from the FFT calculations are in the range from pi to pi For transmission they are multiplied by 2600 and transmitted in data packets consisting of one PacketinfoByte plus six DataBytes per channel PacketlnfoByte UpperX LowerX UpperY LowerY UpperZ LowerZ PacketlnfoByte
83. r lengths from the FFT calculations are multiplied by the concerning gain correction values If the search coil is placed outside of the 3D centre of the magnetic field this allows the correction of the magnetic field inhomogeneity in a certain range See also chapter 14 3 Use of the gain correction Note that all gain correction values are set to 1 0 at the factory If the gain correction is enabled the gain correction values must be individually adjusted for each frequency of each measuring channel To change the values use the concerning Remote Control Function see below Set Gain Corr ChN fM Angle Meter NT User Manual page 29 Description F Data Description Set Gain Mode Data1 0 The gain mode of all four measuring channels is set to automatic gain control AGC This allows the use of different search coils without the need of any system recalibration as long as the parameters of the used search coils are within the technical specifications Due to the AGC the gains change dynamically depending on the field strength the effective area of the used search coils and their angular orientation This ensures an optimal signal to noise ratio of the measuring data Note that in this mode the offset correction is always disabled it is not applicable due to the variable gain caused by the AGC see also below Set Offset Corr Data1 1 The gain of all four measuring channels is set
84. ram Preamplifier Gain Mode Fixed Angle Meter NT User Manual page 57 17 Flowchart sj ejep 104 ejep Buunse w IelI6ip y Jo ejeJ ejep ees epo jueuieunseeui uoee ui p nttusuen jou si ejeq 9joN Z 399A pue A 109A X 399A lU sue ZEZ SH 9 E9S 0 9JE9S W014 pejeos _ Z 199A PUL A 199A X 309A UNA SOYA uses Iz 2A IA Peal IX Joe xew ejeos a Huevos 104 uj6ue1 1O 9 8A JUBUIWOP y euiuueje lt 9jou S Z 399A pue A 199A X 399A Yuuisue1 ZEZ SH 0000t 01 0000t Wo pajeos _ Z 399A pue A 199A X 199A UM SO VG useyes 9jou 99S _ Z uqpue A ld X Iud Wusuen ZEZ SH Id 0 Id Woy pejeos _ Z Wd pue A ud X Iud Ui SOYA useyes oN Dp xId poNW ule lB5uv 1099A lou ees S A poNW 1ndinO g l6uv pue V ejBuy usuel z z S23 Bep 09 0 0 Woy p leos g ejBuy pue V lB5uv ym soya useJes Z JOA pue A 199A q XxX 19A uo peseq g auy pue y auy ajejnojep eea sejnBuy poNW 1ndino SOA 9jou 99S Z 199A A 199A X 199A dI p lqeu Jeyi4 1ndino SOA Zuooguied Z 199A Z PA AMMoguied A 199A A PA XuUoQuied X 199A X PA p lqeu SoA uono uioo ueg ZHODSHO Z 198A Z 199A AMODSHO A 199A A 199A XUODSHO X 199A X 199A
85. rch coil angular orientation in the vertical plane 7 Linearity Error vertical 7 Crosstalk horizontal Linearity Error and Crosstalk search coil vertically turned over 360 horizontally unmoved at 90 Notes 1 to 4 2 0 1 5 1 0 x w 0 5 p o 00 o5 ui 1 0 1 5 2 0 0 45 90 135 180 225 270 315 360 Search coil angular orientation in the vertical plane Linearity Error vertical Crosstalk horizontal Angle Meter NT User Manual page 63 Error Crosstalk 2 0 1 5 1 0 0 5 0 0 0 5 1 0 1 5 2 0 Linearity Error and Crosstalk search coil horizontally turned over 360 vertically unmoved at 0 Notes 1 to 4 amp 5 45 90 135 180 225 270 315 360 Search coil angular orientation in the horizontal plane Linearity Error horizontal Crosstalk vertical Error Crosstalk 2 0 1 5 1 0 0 5 0 0 0 5 1 0 1 5 2 0 Linearity Error and Crosstalk search coil vertically turned over 360 horizontally unmoved at 0 Notes 1 to 4 amp 5 45 90 135 180 225 270 315 360 Search coil angular orientation in the vertical plane Linearity Error vertical Crosstalk horizontal Error Crosstalk 2 0 1 5 1 0 0 5
86. reamplifier i e each is capable to process four measuring channels Up to two Detector Modules can be plugged into the base unit where the left Module is the Main Detector Module which controls the level of the field signals generated by the Generator Module and the right Module optional is the Add On Detector Module The multiplexed input signal from the preamplifier is digitized by an analog to digital converter ADC and processed by a digital signal processor DSP Demultiplexing of the incoming data stream is achieved by the DSP since it controls the MUX of the connected preamplifier The spectral frequency components of the measuring signals are analyzed by computing the Fast Fourier Transformation FFT of the digitized input signal The FFT provides directly the needed signed vector lengths to calculate the angular orientations of the search coils The concerning trigonometric calculations are also executed in real time by the DSP where the synchronization signal from the Generator Module is monitored to obtain phase information The results from the calculations for each measuring channel are simultaneous available in real time as analog output signals and over the serial interface as digital data The format of the outputs is selectable linear angular orientation data search coil angles alpha horizontal plane and beta vertical plane signed vector lengths or signed vector angles from the FFT f1 X axis f2 Y axis and f3
87. rning the processing speed and the resulting update rate of the outputs see J Processing below 3 Vector Angle The signed vector angles for f1 X axis f2 Y axis and f3 Z axis from the FFT calculations are available as analog outputs and as digital data over the serial interface The voltage swing of the analog outputs is adjustable see H Output Swing The output voltages are scaled to the range from pi to pi See also the pinout of the connector with the analog outputs The format of the digital data is described in chapter 10 1 Transmitted Data For information concerning the processing speed and the resulting update rate of the outputs see J Processing below H Output Swing 2 5 V The range of the voltage swing of the analog outputs is set to 2 5 Volt 4 5 V The range of the voltage swing of the analog outputs is set to 4 5 Volt 5 V The range of the voltage swing of the analog outputs is set to 5 Volt 9 V The range of the voltage swing of the analog outputs is set to 9 Volt 10 V The range of the voltage swing of the analog outputs is set to 10 Volt Angle Meter NT User Manual page 18 Parameter Setting Description I Power On Mode 1 Default The parameters of the concerning Detector Module will be reset at each power up of the Angle Meter NT to their default values which are e Display Illumination Medium e Fie
88. rrite toroids with a rather large diameter to ease the winding process e g EPCOS series N30 B64290L0674X830 The primary winding has 30 turns the number of turns of the secondary winding depends on the size of the coil frame 30 turns coil frame up to 50 cm or 45 turns coil frame 50 70 cm Use insulated copper wire diameter 0 5 mm for both windings 15 2 2 Resonance Circuit Tuning Three sets of capacitors in the Matching Box are connected in parallel with the appropriate field coils LC resonance circuits The required total capacitance per resonance circuit depends on the frequency of the field signal and the total inductance of the coil The total inductance of the coil varies depending on the size of the coil frame and the wiring of the coil Angle Meter NT User Manual page 50 Due to the influencing of the wiring on the resulting total inductance the tuning of the resonance circuits assumes completely wired coil frames i e the connection wires must have final lengths and exact twisting Adjust the total capacitance of each set of capacitors to achieve resonance at the specified frequencies Get started by quantifying the total inductance of the coil frames The measured inductance L is used to estimate the required total capacitance C for each resonance circuit C 1 2pifg L X Axis fa 80 0 kHz Y Axis fa 96 0 kHz Z Axis fa 120 0 kHz Use metallized polypropylene film capacitors e g EPCOS series B3265
89. s Mass Nominal magnetic flux density Four channels in the Basic System expandable by the use of an Add On Detector Module to eight channels Applications using more than eight measuring channels are also practicable please contact Primelec for details 230 VAC 10 50 Hz 115 VAC 10 60 Hz on request 250 VA max during normal operation 5 VA max during Standby 2 x 16 characters backlight intensity selectable by the user Main switch at the rear panel Power On StandBy switch multifunctional rotary push button for the menu of each Detector Module operation may be locked by the user 19 3 HU rack mountable or desktop case approx 483 x 140 x 380 mm w x h x d Basic System approx 10 kg Add On Detector Module approx 1 kg Three sine wave field signals crystal controlled digitally synthesized amplified by three physically separated power amplifiers with balanced outputs 80 kHz 96 kHz and 120 kHz 14 Vpp gt GND balanced 28 Vpp Depend on the size of the used coil frame where the nominal output voltages are tuned at the factory to achieve the specified flux density see Nominal magnetic flux density below and an optimal field homogeneity at the 3D centre of the coil frame The factory tuned nominal output voltages may be attenuated by the user in steps of 20 down to zero lt 0 2 Q in the relevant frequency spectrum gt 5 MHz Three coils with two turns each arranged as a monocoque cube
90. s i e four measuring channels To achieve best signal quality the preamplifier is in a separate case which can be placed as close to the search coils as possible To minimize stray pick up it should not be placed in the magnetic field Please not that the aluminum enclosure of the preamp is grounded over the connection cable The preamplifier contains four amplifiers a 4 to 1 multiplexer MUX and an output driver with balanced outputs It can be operated in two gain modes AGC automatic gain control and fixed gain The AGC mode makes it possible to use various search coils under different conditions without the need for any system adjustments by the user and ensures always an optimal signal to noise ratio of the measuring data The fixed gain mode allows an offset correction to minimize the influence of picked up stray signals The system offers auto tuning to automatically achieve optimal values for the gain and offset settings See also chapter 14 5 Choosing the best suited settings for your application If the preamplifier is mounted on a turntable nine slip ring contacts are required for wiring See chapter 12 System Installation and 13 Slip Ring Wiring for additional information An optimal quality of the analog signal is fundamental to achieve best results To avoid problems read chapter 14 System Optimization AN Angle Meter NT User Manual page 10 9 Detector Module Each Detector Module controls one p
91. s packet with thirteen 7 Bit Parameters which are e Display lllum 7 Bit Parameter e Field Signals 7 Bit Parameter e Gain Corr 7 Bit Parameter e Gain Mode 7 Bit Parameter e Offset Corr 7 Bit Parameter e Output Filter 7 Bit Parameter e Output Mode 7 Bit Parameter e Output Swing 7 Bit Parameter e Power On Mode 7 Bit Parameter e Processing Mode 7 Bit Parameter e Setups Mode 7 Bit Parameter e Test Signal Mode 7 Bit Parameter e Module Mode 7 Bit Parameter For a detailed description of the format of the Parameter Data see chapter 10 1 Transmitted Data 15 Data1 4 Causes the Detector Module to transmit the actual settings of the gain correction values for f1 X axis of all four channels packet with four 21 Bit Parameter Note that the gain correction values are multiplied by 200000 for the transfer For a detailed description of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the gain correction values see Set Gain Corr above 15 Data1 5 Causes the Detector Module to transmit the actual settings of the gain correction values for f2 Y axis of all four channels packet with four 21 Bit Parameter Note that the gain correction values are multiplied by 200000 for the transfer For a detailed description of the format of the Parameter Data see chapter 10 1 For a detailed description of the usage of the gain correction values see Set Gain Corr above
92. se the output signals may be invalid and misleading Therefore it is only suggested to enable the correction functions if their usage is really adequate 14 5 4 Output Filter The use of the output filter can be helpful under noisy measuring conditions The lowpass function of the filter may reduce the noise on the output signals significantly where the upper bandwith of the acquired measuring signal is lowered the specifications of the output filter can be seen in the technical data It is suggested to enable the output filter if an improvement of the noise on the output signals can be achieved and if the limitation of the upper bandwith is acceptable by the application 14 5 5 Output Mode The choice of the used output mode Angular Data Vector Length or Vector Angle depends on your demands on the format of the output signals e Angular Data The output signals alpha and beta represent in real time the angular displacements a horizontal plane and b vertical plane of the search coil relative to the system s reference frame coil frame Internally alpha and beta are calculated on the basis of the signed vector lengths from the FFT calculation by trigonometric functions Due to the AC coupled characteristic of this measuring principle drift on the output signals is practically eliminated The use of this output mode is strongly suggested if the goal of your application is to capture the two angles a and b respectively
93. ssing Mode Updated analog outputs Update rate Angular Data Ch12Ch1 Angles alpha and beta of Ch1 only 4 kHz Angular Data Ch1 gt Ch2 Angles alpha and beta of Ch1 and Ch2 2 kHz Angular Data Ch1 gt Ch4 Angles alpha and beta of all channels 1 kHz Vector Length Ch12Ch1 Signed vector lengths f1 f2 and f3 of Ch1 only 4 kHz Vector Length Ch1 gt Ch2 Signed vector lengths f1 f2 and f3 of Ch1 and Ch2 2 kHz Vector Length Ch1 gt Ch4 Signed vector lengths f1 f2 and f3 of all channels 1 kHz Vector Angle Ch12Ch1 Signed vector angles f1 f2 and f3 of Ch1 only 4 kHz Vector Angle Ch1 gt Ch2 Signed vector angles f1 f2 and f3 of Ch1 and Ch2 2 kHz Vector Angle Ch1 gt Ch4 Signed vector angles f1 f2 and f3 of all channels 1 kHz Table 11 1 Update rate of the analog outputs The output voltage swing of the analog outputs depends on the actual setting of the parameter Output Swing see chapter 14 5 6 Output Swing for details The progression of the output voltages in the Angular Data output mode is described in the technical data To make full use of the DAC s dynamic range in the AGC mode the output voltages in the Vector Length output mode are always scaled to fit the dominant vector In the Vector Angle output mode the output voltages are scaled to the range from pi to pi Angle Meter NT User Manual page 37 12 System Installation The figure below shows the required cabling for a system with two Detector Modules i e eighth m
94. standards and regulations for applications on the human being The Angle Meter NT has no approval for such applications and may never be used for applications on the human being To prevent fire or shock hazard do not expose the system to rain or moisture Dangerously high voltages are present inside the device Do not open the cabinet Refer servicing to qualified personnel only Check the standards and regulations of your country and the possible risks for injuries to health before using the Angle Meter NT Only qualified personnel may work with the system and only after becoming familiar with the concerning standards and regulations possible risks and safety information of the Angle Meter NT In no event shall Primelec its employees or its suppliers be liable for any damages whatsoever 2 Measuring Principle The magnetic field search coil technique introduced by Robinson 1 has become the most commonly used method for quantitative studies of eye and head movements in man and in experimental animals The technique is based on phase locked amplitude detection of the voltage induced in a search coil in the external ac magnetic field The angular orientation or displacement of the search coil in three dimensional 3D space is detected by using two or three external magnetic fields which are arranged in space quadrature Demodulation of the induced signals with respect to the magnetic field directions is obtained on the basis of phase
95. t Ch2 Signed vector angles of Ch1 and Ch2 2ms 500 Hz Vector Angle Ch1 gt Ch4 Signed vector angles of all channels 4ms 250 Hz Table 10 1 Update rate of the measuring data over the Serial Interface Angle Meter NT User Manual page 21 Note that the table above indicates only the update rate of the serial data The update rate of the analog outputs is independently of the selected output mode and depends only on the selected processing mode see also chapter 14 5 7 Processing Mode The dataflow consists of data packets which are sequentially transmitted Each transmitted data packet starts with a PacketlnfoByte immediately followed by one or several DataBytes where the number of DataBytes within a packet depends on the type of the transmitted data packet Each PacketlnfoByte indicates the beginning and the type of the transmitted packet i e it determines the meaning of the immediately following DataBytes 10 1 1 Structure of Transmitted Bytes The most significant bit B7 of each transmitted byte in the dataflow determines the meaning of the remaining bits B6 B0 of the concerning byte s e e Ee _ 0 XXXXXXX DataByte XXXXXX contains data according to the type of the data packet 1 XXYYZZZ PacketlnfoByte XX denotes the format of the packet YY denotes the measuring channel number ZZZ is reserved for feature use Table 10 2 Structure of transmitted bytes 10 1 1 1 PacketlnfoByte m
96. t signals significantly Optimal signal to noise ratio The AGC automatically ensures an optimal signal to noise ratio of the measuring signal under all conditions which minimizes the noise on the output signals Gain readjusting may be required Due to the fixed gain of the measuring signal the setting of new fixed gain values may be required after the search coils have been changed The use of the Auto Tuning function is recommended in order to achieve optimal gain values Partly limited system functionality Due to the dynamic change of the signal amplification caused by the AGC the offset correction is not applicable and the functionality of the gain correction is limited Table 14 3 Gain Mode pros and limitations Suggestion Use the AGC mode whenever possible Under difficult measuring conditions the fixed gain mode may be preferred due to the applicability of the gain and offset correction Angle Meter NT User Manual page 44 14 5 3 Gain Correction Offset Correction If there are difficult measuring conditions the use of the gain and offset correction can improve the precision of the output signals dramatically But as mentioned elsewhere in this manual with an optimal homogeneity of the magnetic field and an optimized measuring signal the use of the corrections may no longer be necessary Both correction functions have to be parameterized correctly in order to ensure reliable results Otherwi
97. ta 150 0 09 Angular noise on Ch 1 Alpha Beta 140 0 09 Angular noise on Ch 1 Alpha Beta 130 0 09 Distribution of angular noise cont Notes 1 to 4 amp 8 0 00 0 00 0 00 0 09 0 09 0 09 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 Angular noise on Ch 1 Beta Alpha 270 0 00 0 09 Angular noise on Ch 1 Beta Alpha 270 0 00 Angular noise on Ch 1 Beta Alpha 270 0 00 Angle Meter NT User Manual page 66 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 Distribution of angular noise cont Notes 1 to 4 amp 8 Angular noise on Ch 1 Alpha Beta 120 0 09 40 00 0 09 Angular noise on Ch 1 Alpha Beta 110 0 09 40 00 0 09 Angular noise on Ch 1 Alpha Beta 100 0 18 0 09 0 00 0 09 0 18 Angular noise on Ch 1 Beta Alpha 270 100 80 60 40 20 0 0 09 0 00 Angular noise on Ch 1 Beta Alpha 270 100 80 60 40 20 0 0 00 Angular noise on Ch 1 Beta Alpha 270 100 80 60 40 20 0 0 00 A
98. therefore minimal restriction of the visual field Anodized Aluminum cross section 8 mm Various sizes available Smax 70 cm Various colors available Depends on the frame dimensions for example approx 5 kg for s 70 cm including the required Matching Box Approx 15 uT 80 kHz X axis 12 5 uT 96 kHz Y axis and 10 uT 120 kHz Z axis at the nominal output voltage of the field signals The magnetic flux density may be reduced by the user in steps of 20 down to zero see Nominal output voltages above Angle Meter NT User Manual page 60 Search coils Material Mass DC Resistance Diameter Number of turns Effective area Preamplifier In general Pinout Dimensions Mass Measuring data In general Detection range Resolution of the angular data Output filter Drift Linearity error horizontal Linearity error vertical Crosstalk horizontal vertical Noise Analog outputs Update rate Output voltage swing Output impedance Pinout Preferably double insulated copper wire 20um Depends on material dimensions and manufacturing process for example approx 2 mg for a double insulated copper coil with d 2 mm and n 80 Max 300 ohm 3 ohm 100 ohm typical 2 mm 40 mm typical see also Effective area 1 1000 typical see also Effective area 1 cm 32 cm Aer n D pi 4 The range of the effective area specified above refers to the nominal mag
99. tore the old setting push the knob longer than one second Note that the cursor moves back to the first line of the LCD indicating that the menu is back in the mode which scrolls trough the parameters and the actual setting is displayed in the second line of the LCD To accept the new setting To discard the new setting gt 1 sec To exit the menu and to go back to normal operation push the knob longer than one second during the menu is in the mode which scrolls trough the parameters gt 1 sec e Neither the analog outputs nor the serial interface are updated with the measuring data while the menu is activated The analog outputs freeze at their last updated value and the serial interface is idle i e no measuring data is transmitted until the menu is no longer active and Detector Module is back to normal operation e To disable the activation of the menu of a Detector Module push the knob during the power up sequence of the Angle Meter NT until the message Module Controls Disabled appears in the LCD This prevents the change of any settings by the Menu or over the serial interface Remote Control Functions and ensures that the concerning Detector Module is always in the normal operating mode until the system is set to standby or the power of the device is turned off Angle Meter NT User Manual page 14 9 3 2 Menu Settings Parameter Setting D
100. utine depends on the effective area of the used search coils max 3 seconds After the routine was performed the evaluated gains are applied fixed gain values and the Module is set to the fixed gain mode See also above Fixed gain mode Set Offset Corr Data1 0 The offset correction is disabled not active Angle Meter NT User Manual page 30 Description F Data Description Data1 1 The offset correction is enabled active and the output data of all four measuring channels is calculated on the basis of the individual offset correction values for each frequency of each channel This means that the concerning offset correction values are subtracted from the signed vector lengths from the FFT calculations If the search coil signal is not clean i e if there are picked up stray signals on the measuring signal this allows to minimize the influence of the stray signals on the output signals See also chapter 14 4 Use of the offset correction Note that all offset correction values are set to zero at the factory If the offset correction is enabled the offset correction values must be individually adjusted for each frequency of each measuring channel This can be done automatically by the use of the Remote Control Function Do Auto Tune concerning Offset Correction see below To change the values manually use the concerning Remote Control Function see below Set Offs Corr ChX f
101. x for the resonance circuits Tune the resonance circuits one by one Start in each case with a capacitance value which is slightly lower than estimated and tune the resonance circuits by adding capacitors in parallel until the circuits are exactly in resonance at the specified frequencies i e zero degree phase lag between the output voltage and the output current of the power amplifier Notes e An exactly tuned resonance circuit behaves as an ohm resistive load for the power amplifier During the tuning process the power amplifier may have to drive a capacitive or inductive load Therefore use low field voltages approx 1 V RMS setting see below during the tuning process to prevent overloading the power amplifier Inappropriate handling may destroy the power amplifier e Mismatched resonance circuits will cause phase errors and drift on the system s measuring data outputs or even damage the power amplifiers e See the figure at the end of this chapter for an example of a Matching Box e See the figure at the end of this chapter for an appropriate adapter to measure the phase lag of the power amplifiers output voltage and output current with an oscilloscope Mode X Y 15 3 Field Voltage Tuning Once the resonance circuits are tuned exactly the tuning of the three nominal field voltages X Y and Z is required to calibrate the generated magnetic field Note that the field voltages can achieve hazardous levels precautions in this regard
102. y inaccurately twisted connection wires of the search coils by connectors in the signal path by the preamplifier and so on see chapter 14 2 Optimizing the measuring signal quality If the source of the stray signal is the magnetic field generated by the Angle Meter NT the stray signal may lead to offsets on the output signal Stray signals caused by a radiated field of a third party device may lead to noisy output signals if the radiated frequencies are in the spectrum of the magnetic field frequencies of the Angle Meter NT The offset correction of the Angle Meter NT allows to minimize offsets on the output signals If the offset correction is enabled active the outputs of the measuring channels are calculated on the basis of the individual offset correction values for each frequency of each channel This means that the concerning offset correction values are subtracted from the signed vector lengths from the FFT calculations Note that the offset correction is not applicable if the gain mode is set to AGC the variable signal gain caused by the AGC would lead to invalid corrections The table below shows the measuring signal and the resulting signed vector lengths from the FFT calculations without offset correction Signed vector lengths from the Conditions Measuring signal FFT calculations sVectLenX 18330 sVectLenY 18382 sVectLenZ 25959 Optimal conditions The search coil signal is clean i e no stray sig

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