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Handyprobe 2 user`s manual

1. 0 512 samples 1024 The effects of the different windows are displayed next together with the sinewave signal the spectrum is taken from The sinewave does not fit in the FFT bock and will therefore cause calculation errors Chapter 6 V The measured sine wave TA Rectangular window Hanning window 3 a Hamming window Blackman window Bartlett window When using the rectangular window the amplitude of the spectrum is lower than with the other windows Smearing is larger with the rectang ular window Spectrum analyzer device SPECTRUM 49 50 Again some example illustrations now with a sine wave exactly fitting in the FFT block The measured sine wave Rectangular window Hanning window Hamming window Blackman window B Bartlett window Chapter 6 Similarities with the oscilloscope The spectrum analyzer has some similarities with the oscilloscope The bottom row in the main menu contains choices that are similar to the ones in the oscilloscope devices T hey will not be discussed here Setting up the channel The channel of the spectrum analyzer can be set up to your own de mands The available settings are equal to the settings for the oscilloscope channel except for a few points These points will be discussed here the other points will be referred to the chapter about the oscilloscope Activating
2. Contents iii O SCIIDSCO Pe exiles ecco e e teme iie ees 70 Spectrum analyzer i Ee RR ee re Exe REX Ur RETE 71 True RMSvoltmeter 71 Transientrecorder ee mn 72 NOLES iu cere oe epe cient RD Cn 73 Safety Safety Before you start working with the Handyprobe HP2 first read these safety rules Avoid working alone Take care when measuring at voltages higher than 25V AC or 60 V DC Measuring directly on the LINE VOLTAGE can be very dangerous The crocodile clip of the Handyprobe HP2 is connected with the GROUND ofthe computer Use agood isolation transformer or a differential probe when mea suring at the LINE VOLTAGE or at GROUNDED POWER SUP PLIES In case this has not been considered and the GROUND of the Handyprobe HP2 is connected to a voltage other than ground level a short circuit current will be flowing Because of this short circuit current both the H andyprobe H P2 and the computer can be damaged Do not connect the Handyprobe HP2 to other ports at your PC than the Centronics parallel printer port Connecting the Hand yprobe HP2 to any other port may damage your Handyprpbe HP2 TiePie engineering Kopeslagersstraat 37 8601 WL Sneek Nederland EG verklaring van overeenstemming Wij verklaren geheel onder eigen verantwoordelikheid dat het produkt Handyprobe HP2 waarop deze verklaring betrekking heeft in overeenstemming is met de geharmoniseerde Europese normen EN 5
3. Setting the signal coupling 33 Setting the vertical position 33 Enlarging or reducing the vertical axis 34 Changing the units of the vertical axis 35 Setting up the time DRS tes RE VER ea dev Utere o ees 36 Setting the timebase 36 Magnification of the horizontal axis 37 Reder Zull AE xi er CRT DUREE RI HR Y CRDI 37 Setting the trigger hysteresis 38 Setting the trigger slope vases cree EE VEE ENNEN d Eg 39 Adjusting the trigger level 39 Setting the trigger time out cece eee ees 40 Stopping the display NIE SIN NN EE PR vas eee wees 40 Magnifying a part ofthe screen 41 Measuring with the cross har 41 Storage oscilloscope device HOLD 43 Differences with the oscilloscope eee eee eee eee 43 Automatic storage of measurement data u nanana anana 43 Spectrum analyzer device SPECTRUM 45 D EscriDUOMOTEET 2e cases ed ge ep etes 45 SEES ES AE EE Bem alee SD ROER IE bees 46 oe ER EE RA eia 46 Similarities with the oscilloscope 51 Setting up the channel 51 Setting the sensitivity 51 Adapting the vertical axis 51 Setting up the frequency axis 51 Magnifying the frequency axis 52 Selecting the window 52 Averaging of spectra ee ee ee ee ee ee ee ee 53 Starting a spectrum measurement ee ee ee ee 53 Measuring a harmonic distortion 53 Calculate the spectrum
4. User manual Handyprobe HP2 a multifunctional PC measuring instrument AAS N ATES lt wt yy TiePie engineering engineering ATTENTION Measuring directly on the LINE VOLTAGE can be very dang erous The crocodile clip of the Handyprobe HP2 is connected with the GROUND of the computer Use a good isolation transformer or a differential probe when measuring at the LINE VOLTAGE or at GROUNDED POWER SUPPLIES In case this has not been considered and the GROUND of the Handyprobe HP2 is connected to any voltage other than ground level a short circuit current will be flowing Because of this short circuit current both the Handyprobe HP2 and the computer can be damaged Despite the care taken for the compilation of this user manual TiePie engineering can not be held responsible for any damages resulting from errors that may appear in this book All rights reserved N o part of this book may be reproduced stored in a database or retrieval system or published in any form or in any way electronically mechanically by print photoprint microfilm or any other means without prior written permission from TiePie engineering User manual Handyprobe HP2 a multifunctional PC measuring instrument TiePie engineering IS gt CT ANN LED di y U S engineering Contents Safety 5 Declaration of confirmity ies E
5. 2 4 5 10 and 20 times Triggering To be able to examine a signal the moment of displaying the signal has to be adjustable Therefore an oscilloscope is equipped with a triggering system T his functions as follows firing level arming level triggerhysterese trigger moment The input signal is compared with two levels in the trigger circuitry the arming level and the firing level W hen the input signal passes the arming level the trigger system is armed If the the input signal passes the firing Oscilloscope device live hold 37 38 level the trigger system becomes active and fires a pulse This pulse is used to start the display of the signal The arming level and the firing level are coupled to each other by the trigger hysteresis and their level is determined by the trigger level The firing level corresponds to the trigger level The trigger hysteresis defines at which signal size change can be triggered the change has to be that large that both levels are passed With a small trigger hysteresis it is possible to trigger on small signals If a signal contains a lot of noise a small trigger hysteresis causes triggering on the noise instead of the original signal which gives an unstable display A trigger hysteresis larger than the noise level is then necessary In the latter illustration a signal and the two levels are displayed In this case it is triggered on the rising slope of the signal Th
6. the right mouse button is used for lt Esc Controlling the main menu Each instrument has its own main menu in the lower part of the screen The menu is built of three rows of 6 columns O ne of the buttons of the menu is always displayed inverted That is the cursor indicating the selected choice For controlling the main menu the following keys are available Software 21 22 i k j b S Depending o places the cursor one row up places the cursor one row down places the cursor one column to the left places the cursor one column to the right activates the selected choice displays a list of instruments n the choice after activating a popup Menu appears or the text in the menu changes as well as the instrument setting Controlling popup menus Various settings in the software are made by means of popup menus For controlling the popup Menus the following keys are valid Uo Q O 0 0C OA SE ms Space Character Move the cursor up Move the cursor down Move the cursor to the top of the menu Move the cursor to the bottom of the menu Move the popup menu to the right Move the popup menu to the left Move the popup menu up Move the popup menu down Accept the selected choice Leave the popup menu without changes Leave the popup menu without changes Place the cursor at the choice beginning with that cha racter W hen a popup menu has been moved by means of the lt 6 189 gt keys in combi
7. 3 to be connected to the printer can be selected Note Printer port 1 has the VO address 3BC printer port 2 has the VO address 378 and printer port 3 has the I O address 278 W hen only one printer port is available a conflict arises when a print com mand is given In that case the program asks you to disconnect the H and yprobe HP2 from the computer and to connect the printer to the compu ter Then the printout is generated When printing is finished you are requested to disconnect the printer and to connect the H andyprobe H P2 to the computer again The H andyprobe HP2 is then ready to measure again Hint to avoid connecting and disconnecting the H andyprobe H P2 and the printer often place a second printer port in your PC Chapter 3 Setting the printer type With the SET PRINTER TYPE choice you can choose between an EPSON compatible matrix printer or an HP LASER compatible printer This setting is used for printing out data Setting the date format The program uses date indications at several places like at printer output or on the screen of the transient recorder There are two ways to repre sent the date day month year DD MM YY and month day year MM DD YY The preferable notation can be selected by activating DATE FORMAT from the SETTINGS MENU Behind DATE FORMAT the Current setting is indicated Default text on the printer output With SET USER TEXT you can fill in three text lines These text lines are plac
8. arrows are visible The small arrow next to the border of the window is for the position of a channel the outer arrow isfor the trigger level There are two arrows O nly one arrow can be active displayed normally All other arrows are displayed inverted The arrow indicates the trigger level The trigger level can be set as follows Move the trigger level up Move the trigger level down Move the trigger level to the center Select the next offset or trigger level Select the previous offset or trigger level Move the trigger level to the top Move the trigger level to the bottom Increase the step size 2 times Decrease the step size 2 times OOOOOOOOOO DEAT DEE Switching between crosshair controll and offset trig ger level controll Note the step size for changing the offset level or trigger level can be changed with lt Shift gt and lt Shift gt The trigger level can also be changed with the mouse Place the mouse cursor on top of the arrow of the trigger level to be changed and drag it to Oscilloscope device live hold 39 the correct position Drag press the left mouse button and keep it pres sed while moving the mouse W hen the arrow is at the correct position release the mouse button The mouse cursor will disappear while dragging the arrow and appear again when the button is released Setting the trigger time out W hen the input signal does not meet the trigger conditions no new mea surement data w
9. corresponds with an apparent frequency alias of 250 Hz 1 25 kHz 1 kHz To avoid aliasing the sample frequency must be higher than 2 times the maximum frequency ofthe input signal Aliasing is not always visible on an oscilloscope In the latter illustration it gives a good looking picture It is not apparent that aliasing occurs The next illustration gives an example of visible aliasing This time it is a sine wave signal with a frequency of 25 7 kHz which is sampled at a frequency of 5 kHz The minimal sampling frequency should have been 51 4 kHz For proper analysis the sampling frequency should have been 500 kHz Digitizing After taking a sample of the input signal it is digitised T his is done with an Analog to Digital Convertor ADC The ADC converts the size of the signal to a digital number This is called quantifying The first condition for accurate measurement is to have as many as possi ble quantifying steps This can be realised by using an ADC with a resoluti on as high as possible The resolution of AD C s is often given in bits The number of bits determi nes the number of quantifying steps according the formula Introduction 11 number of quantifying steps 2 umber ofbits A 2 bits ADC has 4 quantifying steps With an input range of 10 Volt this ADC can divide the input range in 4 parts of each 2 5 Volt By increasing the number of bits the resolution increases the number of quatifying steps
10. increases and the sub divisions get smaller The oscilloscope The oscilloscope is an instrument with which electrical voltages varying in time can be displayed With the oscilloscope time dependent electrical signals can be examined easily The Handyprobe HP2 is equipped with two types of oscilloscopes LIVE and HOLD The oscilloscope LIVE measures 1000 samples 2 page The oscilloscope HOLD measures 15000 samples 30 pages The sensitivity range for the channel goes from 125 mV div to 100 V div The timebase goes from 2 5 F sec div to 10 sec div The display of the oscilloscope is built of 500 x 256 wxh pixels which corresponds with 10x8 wxh divisions Left of the display the units of the channel is displayed U nder the display the time axis is displayed The spectrum analyzer The common way to examine electrical signals is in the time domain using an oscilloscope The time domain is used to determine amplitude time and phase information which is necessary to describe the behaviour of an electrical system N ot all electrical systems can be characterised in the time domain Circuits like filters amplifiers oscillators mixers modulators and detectors can be characterised best by their frequency behaviour That frequency behaviour is best obtained by observing the electrical signals in the frequency domain To display the frequency domain an instrument is needed that can disting uish different frequencies from each other
11. measurements For displaying the measured and calculated values 16 methods are availa ble Four of those methods are comparison measurements Chapter 7 gt then HI lt then LO gt lt COMP lt gt LO HI These measurements require a HIGH and a LO W value With the choices SET HIGH VALUE and SET LO VALUE the two values can be set Activating the choices will bring up a dialog box in which the size of the level can be entered in volts Setting the impedance The dBm and POWER measurements require a reference resistance T he value of the resistance can be set by activating SET IMPEDANCE from the CH SET menu The value has to be entered in O hm The default value is 600 O Setting the frequency range The voltmeter has a limited frequency range in which the measurements are performed correctly T his is caused by the fact that the voltmeter takes 200 samples using a certain sampling frequency If the periodical time of the input signal is much larger than the measuring time a wrong value is measured See the next illustration Peak Peak value 200 samples If the time in which the 200 samples are taken is too short in relation to the periodical time of the input signal aliasing can occur see also the chapter about the oscilloscope Voltmeter device VOLT 61 To avoid errors like the one mentioned above the frequency range of the voltmeter has to be set properly The sampling frequency is then changed By ac
12. on paper This is done in a different way than the other instruments The voltmeter can be set to measure acquire at fixed times The measu red value will then be stored on disk or sent to the printer Note When only one printer port is available it is not possible to send the measurements to the printer Setting the time between two measurements By activating the choice TIME from the main menu the time between two measurements can be set A dialog box appears in which the time can be entered in seconds The time has to be between 0 and 300 seconds Note When atime shorter than 0 5 secondsis entered the acquisiti On speed is determined by the changes of display 1 or display 2 Each time a measurement value at the screen changes the measu red value is stored on disk or printed Start an acquisition By activating the choice ACQUIRE a popup menu is displayed from Which a selection can be made whether the data has to be stored on disk or sent to the printer The choice DISK will cause the measurement data to be stored on disk After activating the choice a dialog box appears in which a name for the file has to be entered If a file with that name exists you will be asked whether that file can be overwritten The data in that file will be lost After confirma tion measuring starts At the fixed times a measurement is taken and stored on disk M easuring can be cancelled by pressing lt Esc The choice PRINTER will caus
13. sample is taken every 0 2 50 4 msec With the 0 2 sec choice the minimum duration of the sampling process is 10 0 2 sec 2 0 sec When a key is pressed within these 2 0 sec the sampling process will be interrupted and the program will responds to the key press Note There are 5 different H andyprobe HP2 models they differ in the maximum sampling frequency The available models are 1MHz 2MHz 5MHz 10MHz and 20M Hz Chapter 4 The following time axis ranges can be selected 25F s 5f s 10F s 25f s 50F s 100F s 0 2 msec 0 5 msec 1 msec 2 msec 5 msec 10 msec 20 msec 50 msec 0 1 sec 0 2 sec 0 5 sec 1 sec 2 sec 5 sec and 10 sec div The bold printed values are not available in each H andyprobe HP2 model Magnification of the horizontal axis By activating the TIME MAG choice a popup menu appears displaying 6 software time axis magnification areas When for example the 2 choice has been activated the time axis will be magnified 2 times The magnified part of the screen is indicated by two interconnected arrows at the bottom of the screen The time axis magnifi cation area can be moved using the lt PgUp and lt PgDn gt keys or by mouse Place the mouse cursor on the interconnected arrows press the left mouse button and drag the arrows left or right With the lt gt and lt gt keys the step size can be increased and decreased respectively The following time axis magnification areas can be selected 1
14. the choice CH SET from the main menu gives a popup menu which is almost equal to that of the oscilloscope except for the last line The oscilloscope provides for a choice UNIT the spectrum analyzer for a choice LINEAR dB Setting the sensitivity The sensitivity of a channel can be set in exactly the same way as with the oscilloscope It can be done by means of the choice VOLTS DIV Adapting the vertical axis With the spectrum analyzer you can decide whether the vertical axis will be linear or logarithmic This is done with the setting LINEAR or dB from the menu CH SET The current setting is displayed by the text of the choi ce Activating the choice will make the text and setting change O na logarithmic axis 0 dB corresponds with 1 Volt Setting up the frequency axis By activating the choice FREQUENCY a popup menu appears display ing 15 frequency ranges For example when the 1000 Hz option is activated the maximum fre quency displayed by the spectrum analyzer will then be 1000 Hz The resolution is 1000H 2 500 2 0 Hz Spectrum analyzer device SPECTRUM 51 Note Since there are different Handyprobe models with different fre quency ranges not all of the following frequency ranges are availa ble in the software The following frequency ranges can be selected 10 Hz 25 Hz 50 Hz 100 Hz 250 Hz 500 Hz 1 kHz 2 5 kHz 5 kHz 10 kHz 25 kHz 50 kHz 100 kHz 250 kz 500 kHz 1 MHz 2 5 MHz 5 MHz and 10 MHz Magn
15. transient recorder main menu has several items that are similar to the oscilloscope therefor they are not discussed in this chapter Setting the measuring type By activating MEAS MODE a popup menu appears displaying 5 measu ring methods MOMENTAL the momentary value will be measured true RMS the true RMS effective value will be measured MEAN the mean value will be measured MAX the maximum value of the signal will be measured MIN the minimum value of the signal will be measured The true RMS MEAN MAX and MIN values are calculated from 200 samples To avoid measuring errors the frequency of the measured signal must be around the center frequency set See also Setting the frequency range in the chapter Voltmeter Transient recorder device TRANS 65 T Note W hen true RMS MEAN MIN or MAX is selected the minimum sampling time will be 0 5 sec Setting the frequency range By activating the FREQUENCY choice a popup menu appears display ing 7 center frequencies A frequency range is determined from 0 2 x fenter to 10 Xf ep For example when the 50 Hz option has been activated the signals with afreguency of 10 Hz to 500 Hz will be calculated correctly The frequency setting is only effective when True RMS effective MEAN MAX or MIN values are measured The following center frequencies can be selected 10 Hz 50 Hz 100 Hz 500 Hz 1 kHz 5 kHz 10 kHz 50 kHz and 100 kHz Note W hen the 10 Hz center freq
16. 336 EEC et les amendements 92 31 EEC et 93 68 EEC Sneek 1 9 1999 ir A P W M Poelsma Me TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands Dichiarazione di Conformita CE Dichiariamo sotto la nostra esclusiva responsabilitia che il pro dotto Handyprobe HP2 per il quale vale la presente dichiarzione conforme alle nor me EN 55011 EN 55022 EN 50081 1 e EN 50082 1 condizioni della normativa EMC successive modifiche 92 31 EEC e conformente alle 89 336 EEC e 93 68 EEC ir A P W M Poelsma Ar MV Sneek 1 9 1999 TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands EF Overensstemmelseserkleering Undertegnede erkl rer herved at folgende apparat overhol der beskyttelseskravene i R dets direktiv 89 336 E F om elektromagnetisk kompatibilet EMC Identification af apparat Kategori M leinstrument Model type Handyprobe HP2 Standarder der er anvendt som grundlag for erkl ring eller henvisning til den pravningsrapport der er udstedt af et be myndiget laboratorium EN 55011 EN 55022 EN 50081 1 og EN 50082 1 CE m rket angiver kun overensstemmelse med EM C direk tiv 89 336 E F Sneek 1 9 1999 ir AP WM Poelsma ly d TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands EC declaraci n de conformidad Nosotros declaramos bajo nuestra propia responsabilidad que el producto Handyprobe HP2 para el cual e
17. 5011 EN 55022 EN 50081 1 en EN 50082 1 Volgens de bepalingen van de EMC richtliin 89 336 EEG gewijzigd door de richtlijn 92 31 EEG en 93 68 EEG r APA Sneek 1 9 1999 v TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands EG Konformitatserklarung Wir erkl ren in Eigenverantwortlichkeit hiermit dafs das Pro dukt Handyprobe HP2 f r das diese Erkl rung g ltig ist mit EN 55011 EN 55022 EN 50081 1 und EN 50082 1 gem den Anforderungen des EMC standards 89 336 EEC und den Zusatzbestimmungen 92 31 EEC und 93 68 EEC Ubereinstimmt Sneek 1 9 1999 ir A P W M Poelsma Declaration of confirmity Declaration of confirmity TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands EC declaration of Confirmity We declare on our own responsibility that the product Handyprobe HP2 for which this declaration is valid is in compliance with EN 55011 EN 55022 EN 50081 1 and EN 50082 1 according the conditions of the EMC standard 89 336 EEG and the amendments 92 31 EEC and 93 68 EEC Sneek 1 9 1999 ir A P W M Poelsma AT MV VET TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands D claration de conformit C E N ous d clarons sous notre responsibilit que le produit Handyprobe HP2 pour lequel cette d claration est valide est conforme aux EN 55011 EN 55022 EN 50081 1 et EN 50082 1 selon les conditions du standard CEM N 89
18. E EE EE RE eee eee 7 Introduction se toner EE DES EE EE dei EPIS 9 RS EER OE EL EE TE EO 9 acc M 10 Be alie RE OR telo robe n pa na roa a ide N 11 The OSCIIGSCODE uo DE RE sept dccus ER ue t Es 12 The spectrum analyzer cece cece EE SE EE Ee ee ee 12 The voltmeter 0 ccc cece ee ee ee ee ee ee ee ee ee 14 The transient recorder ccc cece cece ee ee 14 Hardware installation ccc eee 17 ell EES 19 Structure of the program cs aae atr DOE ERO ERR RE EAR 20 Starting the program 20 Controlling the program 21 Controlling by mouse 21 Controlling the main men 21 Controlling popup menus 22 Help SCRE ac ate tace veu cepe ge d Da eee es 23 Program settings EE 23 Setting the main menu type cc cece eee EE ee 23 Saving instrument settings 24 Loading instruments settings 25 Setting the file type for measurement data 25 Setting the location offiles ccc cece eee eens 26 Setting the printer port 26 Setting the printer we 27 Default text on the printer output 0 c cee eee 27 Setting the screen color 27 Storing measurement data on dek 27 Loading saved measurement data 28 Contents Printing measured data 29 Choosing an instrument EE EE ee ee ee ee 29 Terminating the program 30 Oscilloscope device LIVE 31 UC rd oe fect RE RR ke RI ED l 31 Setting up the channel 32 Setting the sens 32
19. S both a popup menu and a text window appear In the popup menu the names of the settings entered with the choice COMMENT FOR SETTIN GS are listed In the text window the accompanying text entered with TEXT FOR SET TIN GS is shown Setting the file type for measurement data With the choice SET DATAFILE TYPEthe file type with which the data will be stored on disk can be set Software 25 26 Note For compatibility reasons the H andyprobe H P2 software uses the 2 channel data file format that is used with the other TiePie measu rement software In the Handyprobe HP2 software the data for channel 2 is ignored but the space is used in the file format When the BYTE option is selected the data file exists of records of 4 bytes byte 1 and 2 are the value of CH 1 and byte 3 and 4 are the value of CH2 W hen the ASCII option is selected the data file exists of an ascii file of 4 columns separated by a comma Column 1 is the sample number co lumn 2 the sampling time column 3 the voltage value of CH1 and column 4 is the voltage value of CH 2 Setting the location of files With the choice DEFAULT DIRECTORY the default directories for the H andyprobe HP2 the print files and the data files can be set The default directory for the Handyprobe HP2 is the directory containing the files HP2 EXE HP2 EN G HLP HP2 ENG IN F and HP2 FNT Setting the printer port With the choice DEFAULT PRINTER PORTthe parallel printer ports 1 2 or
20. ZE position By activating the ONE SHOT menu the text in the menu changes from Chapter 4 ONE SHOT to MEASURE After measuring the signal the text changes back to ONE SHOT W hen a key is pressed during measuring MEASU RE the sampling process will be terminated immediately Samples taken up to the moment the key is pressed can be viewed the remaining sam ples are 0 Magnifying a part of the screen By activating the choice ZOOM a popup menu appears displaying 2 options The FULL choice displays the signal fully T he x axis and y axis magnifica tions are set at 1 and the offset levels at 0 With the WINDOW option a rectangular magnification area can be indica ted using the 7136 gt keys or the mouse O ne corner has to be indica ted first followed by the lt Enter gt key or the left mouse button Then the second corner has to be indicated followed by the Enter key or the left mouse button Cancelling the zooming can always be done by means of the lt Esc gt key or the right mouse button Measuring with the cross hair After the measured signal is displayed a crosshair appears W ith the cros shair absolute and relative time and voltage measurements can be perfor med Controlling the crosshair is done with the following keys h Setting the absolute zero y Setting the relative zero u Move the crosshair to zero Move the crosshair up x Move the crosshair down Move the crosshair to the left Move th
21. ackman Bartlett window distortion measuring 10 harmonics of the ground frequency True RMS voltmeter measuring method true RMS mean min max momentary dBm power crest factor and frequency values display abilities CH1 CH2 CH1 CH2 CH1 CH2 CH2 CH 1 CH 1 CH2 CH2 CH1 CH1 CH2 gt then then COMP HILO MAX MIN LOG CH 1 CH2 and LOG CH2 CH 1 display height 1 2 inch 25 50 mm depending on the monitor frequency range 10 Hz 50 Hz 100 Hz 500 Hz 1 kHz 5 kHz 10 kHz voltage range 500 mvolt 400 volt full scale Specifications 71 maximum overload voltage 500 volt peak to peak data acguire to disk and to printer Transient recorder measuring time between two measuring points 0 01 300 sec at a PC XT the minimum time is 0 05 sec maximum number of measuring points to be taken 30 000 time axis magnification 2 20 times gain factor 5 5 times offset factor 10 000 10 000 measuring method true RMS mean min max and momentary Notes If you have any suggestions and or remarks regarding the program the Handyprobe H P2 or the manual please contact t TiePie engineering Q TiePie engineering P O Box 290 Koperslagersstraat 37 8600 AG SNEEK 8601 WL SN EEK The Netherlands The Netherlands Fax 31 515 418 819 Tel 431515 415 416 Website http www tiepie nl Email info tiepie nl Rev 1 01
22. and measure the signal size at the different frequencies An instrument that can display the frequency Chapter 1 domain is the spectrum analyzer It graphically displays voltage as a function of frequency In the time domain all frequency components of a signal are seen summed together In the frequency domain complex signals signals composed of more than one frequency are separated in their frequency components where the voltage of each frequency component is displayed The frequency domain contains information which is not available in the time domain Therefore the spectrum analyzer has certain advantages compared with an oscilloscope W ith a spectrum analyzer small harmonic distortions on a signal can be displayed better than on an oscilloscope A sine wave may look good in the time domain however in the frequency domain the harmonic distortion is visible A noise signal may look fully random in the time domain in the frequency domain it can appear that one frequency is dominantly present In the frequency domain it is very simple to determine carrier fre quency modulation frequency modulation level and modulation distortion from a modulated signal AM or FM The Handyprobe HP2 is equipped with a spectrum analyzer The spec trum analyzer takes 1024 samples of which a spectrum of 512 spectral components is calculated by means of FFT The sensitivity of the channel can be set from 125 mV div to 100 V div The freq
23. ay 1 plus data of display 2 Chapter 7 gt then The data is compared with the HIGH VALUE When the data is higher than HIGH VALUE PASS is displayed W hen the data is smaller than HIGH VALUE LO is display ed lt then The data is compared with the LOW VALUE When the data is lower than LOW VALUE PASS is displayed W hen the data is higher than LOW VALUE HI is displayed gt lt COMP The data is compared with the LOW VALUE and the HIGH VALUE When the data is higher than HIGH VALUE HI is displayed W hen the data is lower than LOW VALUE LO is displayed When the data is lower than or equal to HIGH VALUE AND higher than or equal to LOW VALUE PASS is displayed lt gt Hi Lo The data is compared with the LOW VALUE and the HIGH VALUE When the data is higher than HIGH VALUE PASS is displayed When the data is lower than LOW VALUE PASS is displayed When the data is lower than or equal to HIGH VALUE AND higher than or equal to LOW VALUE LO is displayed MAX Display the maximum value of the data MIN Display the minimum value of the data LOG 1 2 measured value CHI 20 log measured value CH2 LOG 2 1 50 og measured value CH2 measured value CH I Displaying the measured values The voltmeter can display the measured valyes in several ways on 2 to 6 displays By selecting DISPLAYS from the main menu a popup menu appears in which the number of displays and the display settings can be s
24. been installed is indicated at the bottom of the popup menu This printout is full page containing extra information like date and time of the measurement the comment lines and the U SER TEXT Comments can be added to the printout using the COMMENT choice W hen activated a dialog box appears in which three lines of text can be entered These comments entered here are printed together with a prin tout The comments are stored on disk together with the data So each data file has its own comments The key lt F1 gt gives an overview of valid function keys in the editor Choosing an instrument By activating the choice DEVICE menu a popup menu appears display ing 6 choices W hen the QUIT choice is activated the program will be terminated The other options activate the indicated measuring instrument The measuring instruments the devices to be selected are Software 29 LIVE oscilloscope HOLD storage oscilloscope SPECTRUM spectrum analyzer VOLT voltmeter TRANS transient recorder This menu can also be activated by means of the lt Esc gt key or the right mouse button if no other menu is active Terminating the program 30 The popup menu DEVICE can be invoked from all program sections by means of the Esc key or the right mouse button The QUIT option enables you to leave the program and takes you back to the operating system DOS The popup menu DEVICE can also be invoked with the lt Esc gt key or
25. bers along the Chapter 4 vertical axis are also changed The GAIN can be used to invert a signal by entering a negative value Changing the units of the vertical axis Along the vertical axis normally the voltage of the input signal is projected The unit of measure is then Volt and the numbers along the axis corres pond with the size of the input signal The Handyprobe H P2 oscilloscope allows you to create another definition of the vertical axis By means of the choice UNIT from the CH SET menu the units of measu re of the vertical axis can be changed After activation a popup menu with 11 choices appears The unit that is selected is displayed at the top of the vertical axis It is also placed on the paper when printed out The possible choices are VOLT AMPERE DEGREE F DEGREE C WATT PERCENT METER KILOGRAM NEWTON COLOMB and BAR If you are measuring e g with a temperature probe you can choose DE GREE C for the units By activating the choice UNITS VOLT from the menu CH SET a mul tiplication factor can be entered for the units of the vertical axis A dialog box appears in which the factor is entered The numbers along the vertical axis are multiplied by the factor and replaced by the result Another application is the previously mentioned example with the tempe rature probe Suppose the temperature probe gives a voltage change of 1 volt at a temperature change of 5 degrees By entering the factor 5 the tempera
26. ctivating the choice READ DISK a popup menu appears giving an overview ofthe data files contained in the indicated default data directory With the 7336 gt keys a file can be selected W hen a selection has been made the data and set files will be read from disk W hen the data is not from the measuring instrument only the data file is read or an error mes sage appears The following file operations can be carried out with the function keys View the file information size date and time View the file only text files F4 Delete the file F5 Rename the file F6 Copy the file SREB EE Enter anew directory mask and or path and or disk When lt F4 gt lt F5 gt or lt F6 gt is used both the DAT file and the GEG file are acted on Chapter 3 Printing measured data There are two ways to print the measurement data The first way is pressing lt Shift PrtSc gt A quarter page size screen dump is made containing only the information that is found on the display The second way is activated by the menu choice PRINT A popup menu appears displaying 2 choices The DISK choice requests for a file name to create the print file This print file can be sent to the printer using the DO S command COPY B file name PRN where filename stands for the file name you entered in the input box With the PRINTER option the screen can be printed out on an EPSON HP LASER or a compatible printer W hat printer type has
27. d date of measuring are writ ten the storage oscilloscope will wait for the next signal to meet the trigger conditions If that occurs new samples are taken and stored on disk in a new file The file serial number will be increased by one from the previous number The measuring and storing of data can be stopped by pressing Esc READ DISK is used to load stored data for examination This system is very usefull when e g an interference glitch has to be measu red Suppose at unpredictable times a glitch occurs By setting the trigger delay to INFINITE and selecting AUTO DISK the storage oscilloscope may wait days for the glitch but when it occurs it is measured and stored The time and date of the occurrence are stored and appear on a printout Note When the sensitivity of the channel is set to AUTO ranging the oscilloscope uses 1 to 10 measurements depending on the input Signal to find a suitable sensitivity Chapter 5 Chapter 6 Spectrum analyzer device SPEGTRUM The storage oscilloscope measures and displays signals in the time do main the voltage is plotted against the time It is also possible to display measurement data in the frequency domain the data is then plotted against the frequency For this method the spectrum analyzer is used Description of FFT The spectrum analyzer is using the Fast Fourier Transform FFT principle For this transform 1024 samples are taken with a previously set sample speed Wi
28. e crosshair to the right D Dam m Mirror the crosshair on the relative x axis OOOO OOO 0 Oscilloscope device live nold A 42 r Mirror the crosshair on the relative y axis S D ecrease the step size twice Increase the step size twice 2 aao f Switching between crosshair controll and offset trig ger level controll Absolute zero is that point at the screen where voltage and time are zero let most in the center of the screen Relative zero is that point set by moving the crosshair to the intended point and subsequently pressing lt Shift Del gt The time and voltage values according the crosshair position are displayed on the screen the voltage value in the upper right corner of the screen and the time value at the right most end of the time axis The values are displayed inverted The crosshair can also be moved by means of the mouse This is done by placing the mouse cursor at the crosshair press the left mouse button and move the mouse keeping the left mouse button pressed W hile positio ning the crosshair with the mouse the mouse cursor disappears When the correct position is achieved the left mouse button can be released and the mouse cursor appears again Chapter 4 Chapter 5 Storage oscilloscope device HOLD Differences with the oscilloscope The storage oscilloscope HOLD is quite similar to the oscilloscope LIVE there are a few differences which will be described here For the rest i
29. e of the DC voltage of 1 volt is 1 volt The mean value of a true sine with a RMS value of 1 volt is 0 volt MAX The maximum value of the sampled data is determined The maxi Chapter 7 mum value of a DC voltage of 1 volt is 1 volt The maximum value of atrue sine with a RMS value of 1 volt is 1 41 volt MIN The minimum value of the sampled data is determined The minimum value of a DC voltage of 1 volt is 1 volt The mini mum value of a true sine with a RMS value of 1 volt is 1 41 volt dBm The value of the sampled data is converted into decibels Converting is done by means ofthe formula 1000 value 2 dBm 10 log reference resistance With value the RMS value of the measured data is meant The reference resistance can be set with the SET IMPE DAN CE option POWER The value of the sampled data is converted into a power Converting is done by means ofthe formula 2 POWER value reference resistance With value the RMS value of the measured data is meant The reference resistance can be set with the SET IMPE DAN CE option CREST The value of the sampled data is converted into a crest fac tor Converting is done by means ofthe formula CREST peak value RMS value The peak value is the peak voltage relative to the zero line ofthe signal FREQ The frequency ofthe offered signal is determined Changing the units of measure The units of measure displayed can be config
30. e signal passes the two levels from low to high When triggering on the falling slope of a signal the two levels are swapped Then the signal has to pass the two levels from high to low to generate a trigger Setting the trigger hysteresis By activating the choice HYSTERESIS a popup menu appears display ing 12 trigger hysteresis options For example when the 0 5 DIV option has been activated the trigger hysteresis will be 0 5 division of the voltage range set This means that the signal has to come out at aminimum of 0 5 division below the trigger level set for a positive trigger slope When the signal has much noise the trig ger hysteresis can be set high to ensure that triggering is satisfactory W hen a signal has less noise the trigger hysteresis can be set low allowing triggering at low signal levels For setting the trigger level see offset and trigger levels The following trigger hysteresises can be selected 0 0 125 0 25 0 5 0 75 1 0 1 25 1 5 1 75 2 0 2 25 and 2 5 DIV Chapter 4 T Setting the trigger slope By activating the choice SLOPE SLOPE the text in the menu choice changes from SLO PE to SLO PE or vice versa In the SLO PE position triggering takes place on a rising slope of the signal to be measured and in the SLO PE position on a falling slope Adjusting the trigger level The adjustment ofthe trigger level is not done by means of a popup menu At the lefthand side of the screen two small
31. e the measurement data to be sent to a printer After activating measuring starts At the fixed times a measure ment is taken and the value is sent to the printer M easuring can be cancel led by pressing lt Esc Voltmeter device VOLT 63 In both modes the measurement values are preceded by a block of infor mation In that block is indicated how the channel is set and how the HIGH LOW and RELATIVE LEVELS are set Each measurement is prece ded by the time and date of the measurement If a measured value is higher than the selected input range is display ed This will also be stored on disk or printed Changing the display characters 64 By activating the DIGIT SET choice a popup menu appears displaying 5 digit thicknesses For example when the 4 PIXELS choice has been activated the digit thickness will be 4 pixels The following digit thicknesses can be selected 2 4 6 8 and 10 pixels Chapter 7 Chapter 8 Transient recorder device TRANS T The transient recorder is direct registering measuring instrument display ing the changes ofthe input signal graphically on the screen or on paper The transient recorder measures at settable fixed times and processes the measured value if necessary The number of measurements to be taken is also settable Note The transient recorder displays a measured sample immediately the oscilloscope takes all samples and then displays the complete page The
32. ed at the top on each print out with the PRINT option For example you can fill in your name and address information in these text lines The text lines are saved in the HP2 DEF file At the start of the program the text lines are read automatically Setting the screen colors W hen an EGA VGA color monitor is available the colors of the back ground the foreground Channel ref channel and the cross hair can be set While changing the new color is displayed immediately The color brightness can be changed using the lt 7 gt keys or the mouse Also a selection can be made between a color or a black and white display Storing measurement data on disk By activating the WRITE DISK choice a file name is requested A file name without extension has to be entered The data are stored in filena me DAT and the corresponding instrument setting in filename G EG In case the file name already exists the program asks to overwrite the Software 27 D existing file If there is insufficient disk space an error message appears A file with the extension DAT and a file with the extension GEG are made during a WRITE DISK The data format is determined by SET FILE TYPE Note The voltmeter has a completely different way of storing measure ment data This will be described in the chapter Voltmeter The transient recorder always stores data on disk so the choice WRITE DISK is not available Loading saved measurement data 28 By a
33. ersa In the hardware a capacitor is switched into AC or out of DC the signal path In COUPLING DC the complete signal AC DC at the input is passed through In COUPLING AC only the AC component of the input signal is passed through It is then possible to examine e g a 20 mV ripple on a 30 V DC voltage since only the ripple is passed through and the DC volta ge not AC voltages with a frequency lower than 4 Hz are not coupled correctly Displaying the measured value By activating the DISPLAY CHx choice a popup menu appears display ing 16 options For both column of displays there is a menu Note The voltmeter can have up to six displays to represent values of the input signal The displays are divided in two columns one on the left and one on the right In the following description ch1 and display1 mean a display in the left column and ch2 and display2 mean a dis play in the right column at the same row The option choosen determines how the data of display 1 or display 2 will be displayed The options are CH1 Display data of display 1 CH2 Display data of display 2 CH1 CH2 Display data of display 1 multiplied with data of display 2 CH1 CH2 Display data of display 1 divided by data of display 2 CH2 CH1 Display data of display 2 divided by data of display 1 CH1 CH2 Display data of display 1 minus data of display 2 CH2 CH1 Display data of display 2 minus data of display 1 CH1 CH2 Display data of displ
34. et Voltmeter device VOLT 57 58 Set the number of displays By selecting NUMBER OF DISPLAYSa popup menu appears with the choices 2 DISPLAYS 4 DISPLAYS and 6 DISPLAYS When 6 DISPLAYS is selected 6 displays are available all individually configurable The left hand side displays are numbered 1 3 and 5 the right hand side displays are numbered 2 4 and 6 Selecting the possibilities of the displays With the choices SET DISPLAY1to SET DISPLAY6 the properties of the displays can be set Processing the measured data By activating MEASURING a popup menu appears displaying 9 calcula tions The option choosen determines how the data will be calculated The following options can be selected True RMS The true RMS value of the sampled data is calculated The true RMS value Root Mean Square is the value of a Casual voltage form identical to a DC voltage dissipating the same power in a resistance An AC voltage of 1 volt RMS is identical to a DC voltage of 1 volt Most cheap voltmeters only point the right value at a true sine voltage when an AC voltage is measured The H andyprobe H P2 always points the correct value at the true RMS handling PEAK TO PEAK The peak to peak voltage of the sampled data is determined The peak to peak voltage of a DC voltage is zero The peak to peak voltage of a true sine with a RMS value of 1 volt is 2 828 volt MEAN The mean value of the sampled data is determined The mean valu
35. frequency 5 kHz 20 0 msec Sample frequency 2 5 kHz 50 0 msec Sample frequency 1 0 kHz 100 msec Sample frequency 500 Hz 0 20 sec Sample frequency 250 Ha 0 50 sec Sample frequency 100 Ha 1 00 sec Samplefrequency 50 Hz 2 00 sec Sample frequency 25 Ha accuracy of time base 0 01 96 time axis magnification 2 20 times setting accuracy time axis magnification 0 25 96 y axis magnification 5 5 times triggering positive slope negative slope trigger sensitivity 0 25 2 25 DIV trigger resolution 0 01 times full scale trigger time out 0 Infinite external triggering keyboard offset range 0 100 96 offset resolution 0 01 times full scale invert yes compare yes Chapter 9 xy mode no Spectrum analyzer frequency range 0 0195 10 Hz res 0 0195 Hz 0 0488 25 Hz res 0 0488 Hz 0 0977 50 Hz res 0 0977 Hz 0 195 100 Hz res 0 195 Ha 0 488 250 Hz res 0 488 Hz 0 977 500 Hz res 0 977 e 195 1000 Hz res 1 95 Hz 4 88 2500 Hz res 4 88 Hz 9 77 5000 Hz res 9 77 Hz 19 5 10000 Hz res 19 5 Hz 48 8 25000 Hz res 48 8 Hz 97 7 50000 Hz res 97 7 Hz 195 3 100000 Hz res 1953 Hz 488 3 250000 Hz res 4883 Hz 976 5 500000 Hz res 976 5 Hz 1953 1 1000000 Hz res 1953 1 Hz 3906 2000000 Hz res 3906 Hz 9765 5000000 Hz res 9765 Hz 19531 10000000 Hz res 19531 Hz freguency axis magnification 2 20 times y axis linear dB windows rectangle H anning Hamming Bl
36. from the HOLD signal 54 Voltmeter device VOLT ses auem ERR RR 55 Setting up the channel EE e ee prr e eh RE dek 55 Setting the input range 55 Setting the signal coupling 56 Displaying the measured value 56 Displaying the measured values 0 c cece eee eee 57 Set the number of displays 0 cc cece cece eee 58 Selecting the possibilities of the displays 58 Processing the measured data ccc cece eee ees 58 Changing the units of measure 59 Changing the units per volt cece cece 60 Relative measurements 0 cece cece eee eee 60 Comparison measurements 60 Setting the impedance Die EE cad dew aac ee 61 Setting the frequency range 61 Perform measurements ee ee ee ee eens 62 Storing measurement values on disk or paper 63 Setting the time between two measurements 63 Start an acquisition EE 63 Changing the display characters Ee ee ee ee 64 Transient recorder device IRAN 65 Setting the measuring type cc cece cece Ee ee eens 65 Setting the frequency range 66 Setting the sampling time 66 Setting the number of sample 67 Clear the screen M METTE 67 Start a measurement 67 Go to EE e We ue 68 Specifications us cse ERA RR pacem EEN ae ER Ea 69 Ee ET E 69 A D CONVErOF ai sees EED eR ERR HEERS EE Ex 69 er MP TIE 69 ejt i ee EE 70 COMMON OR EET 70
37. harmonic distortion can arise since the periodic waveform created by the FFT can have sharp disconti nuities See also the following illustration These discontinuities are also called calculation errors Chapter 6 AN Amplitude start measured FFT block 1024 samples ad i tijd This means that because of the calculation errors extra frequency compo nents are generated around the true frequency Because of this smearing the amplitude of the true frequency decreases since the area under the curve remains the same The smearing caused by the calculation errors can be decreased by pla cing a window on the FFT block of 1024 samples in such a way that the ends ofthe FFT block are smoothly tapered to zero and discontinuities do not occur when the FFT treats the windowed block as one period of a periodic signal Each sample of the FFT block is therefore multiplied by a factor whose size is dependent on the position of the sample in the FFT block See also the following illustration E piso MERE i windowed i time i FFT block i i i 1024 samples Spectrum analyzer device SPECTRUM 47 48 The software supports five different windows rectangular all data remains the same Hanning Hamming Blackman Bartlett c c c5 c5 c A graphical representation of the different windows is given in the next illustration Rectangle Blackman Bartlett Hamming Hanning amplitude
38. ifying the frequency axis By activating the FREQ MAG choice a popup menu appears displaying 6 magnification areas When for example the 2 option has been activated the frequency axis will be magnified 2 times The magnified part of the screen is indicated by two interconnected arrows at the bottom of the screen The frequency axis magnification area can be moved using the lt PgUp gt and lt PgDn gt keys or the mouse by placing the mouse cursor on the interconnected arrows and clicking the left mouse button while moving the mouse button must be kept pressed With the lt gt and lt gt keys the step size can be increased and decreased respectively The following frequency axis magnification areas can be selected 1 2 4 5 10 and 20 times Selecting the window 52 By activating the choice WINDOW a popup menu appears displaying 5 window types These windows are used to reduce calculating errors during the FFT trans formation See at the beginning of this chapter for an explanation about FFT and windows The following window types can be selected rectangle no window Hanning Hamming Blackman Bartlett Chapter 6 Averaging of spectra W hen the spectrum of a non periodic signal for example noise is measu red AVERAGE can be used By activating the choice AVERAGE a popup menu appears displaying 8 options When AVERAGE is set to 10 10 spectra will be measured calcu lated and averaged After ca
39. ill be displayed and the last displayed signal will remain on the screen This can be very inconvenient with unknown signals since it is not known how the trigger circuitry has to be set To provide in that case for a representation of the input signal on the screen a trigger time out Setting is available With the time out setting it is determined how long the delay will be for a trigger pulse If that time expires the available data will be displayed This will not result in a stable display but it will give an impression how the trigger has to be set By activating the choice TIME OUT from the main menu a popup menu appears with 12 choices for the trigger time out 0 DIV 10 DIV 20 DIV 50 DIV 100 DIV 200 DIV 500 DIV 1000 DIV 2000 DIV 5000 DIV 10000 DIV and Infinite For example when the 50 DIV option has been activated the signal will be controlled for 50 time divisions maximally If the signal does not comply with the trigger level set the trigger slope and the trigger hysteresis within 50 time divisions it will nevertheless be measured after 50 time divisions Stopping the display 40 By activating the LIVE FREEZE choice the text in the menu changes from LIVE to FREEZE or vice versa In the LIVE position the oscilloscope continuously takes 500 samples and displays them on the screen In the FREEZE position no samples are taken and the samples last taken are displayed on the screen AONE SHOT menu is added in the FREE
40. imebase of the oscilloscope one step faster or slower and check whether the signal at the display changes accordingly If that does not give any clearance you can determine the frequency of the input signal with the spectrum analy zer Therefore you must set the frequency range of the spectrum analyzer to the maximum to avoid aliasing with the spectrum analyzer For more information see the chapter Spectrum Analyzer Setting up the channel 32 The channel of the H andyprobe H P2 oscilloscope is completely configura ble With the choice CH SET from the main menu a popup menu is called With the choices from this menu the channel can be configured Setting the sensitivity By activating the choice VOLTS DIV a popup menu appears displaying 10 voltage ranges When e g 2 has been activated a voltage range of 2 volts div will be set that is the maximum voltage to be measured is 8 volt The AUTO option provides for setting the voltage axis auto matically The following ranges can be selected 125mV 250mV 500mV 1V 2V 5V 10V 20V 50V and 100V per division Chapter 4 Setting the signal coupling By activating the choice COUPLING AC DC the text changes from COUPLING AC to COUPLING DC or vice versa In the hardware a capacitor is switched into AC or out of DC the signal path In COUPLING DC the complete signal AC DC at the input is passed through In COUPLING AC only the AC component of the input signal is passed th
41. jumped to can be given For example when a measurement has been made involving 15 000 values then the 15 000 sample value can be jumped to straight aw ay by entering 15 000 68 Chapter 8 Chapter 9 Specifications Hardware A D convertor sampling frequency 1 2 5 10 or 20 MHz input sensitivity full scale 500 mvolt resolutie 3 91 mvolt 1 volt resolutie 7 81 mvolt 2 volt resolutie 15 6 mvolt 5 volt resolutie 39 1 mvolt 10 volt resolutie 78 1 mvolt 20 volt resolutie 15 6 mvolt 50 volt resolutie 391 mvolt 100 volt resolutie 781 mvolt 200 volt resolutie 1 56 volt 400 volt resolutie 3 91 volt maximum overload voltage 500 volt AC 50 Hz input impedance 1Mohm 30 pF coupling AC DC resolution 8 bits 0 39 accuracy 1 1LSB bandwidth DC to2 MHz General operation temperature 15EC 25 C dimensions h x Ix w 22 x 125 x 43 mm weigth approx 260 gram cable length approx 67 inch 1 7 m Specifications 69 Software 70 Common hardcopy matrix deskjet and laser printer Oscilloscope timebase 2 5 usec Sample frequency 20 MHz 5 usec Sample frequency 10 MHz 10 usec Sample frequency 5 MHz 25 usec Sample frequency 2 MHz 50 usec Sample frequency 1 MHz 100 usec Sample frequency 500 kHz 200 usec Sample frequency 250 kHz 500 usec Sample frequency 100 kHz 1 0 msec Sample frequency 50 kHz 2 0 msec Sample frequency 25 kHz 5 0 msec Sample frequency 10 kHz 10 0 msec Sample
42. lculated The frequency axis and the voltage axes are adjusted to the value of the HOLD device 54 Chapter 6 Chapter 7 Voltmeter device VOLT The Handyprobe H P2 is equipped with a voltmeter with digital display The voltmeter functions as follows 200 points are sampled The measured data is processed e g for calculating the RMS value or the mean value 9 options can be carried out The calculated values are displayed e g add the values of displayl and display2 and display on display1 16 different display modes are available Because of the computations and display modes there are many options 100 to measure a signal with the voltmeter Setting up the channel As noticed the channel can be configured in many ways Activating the choice CH SET brings up a popup menu in which the settings for the channel are available Setting the input range By activating the VOLTS DIV choice a popup menu appears displaying 10 voltage ranges W hen e g 10 has been activated a voltage range of 10 volts full scale will be set that is the maximum voltage to be measured is 10 volt The AUTO option provides for setting the voltage axis auto matically The following ranges can be selected 500 mV 1 V 2 V 5V 10 V 20 V 50 V 100 V 200 V and 400 V Voltmeter device VOLT 55 56 Setting the signal coupling By activating the choice COUPLING AC DG the text changes from COUPLING AC to COUPLING DC or vice v
43. lculating each spectrum the results are display ed immediately The averaging process can be interrupted by pressing the Esc key or the right mouse button The following choices for averaging are available 1 2 5 10 20 50 100 and 200 Starting a spectrum measurement The sampling process is started by activating the choice MEASURE On the screen the text MEASURING PLEASE WAIT appears After the sampling process the spectrum is calculated using FFT and the message CALCULATE SPECTRUM 1 PLEASE WAIT Esc Exit appears on the screen When there are more calculations set by means of the AVERAGE menu the first text will be displayed on the screen followed by the second one Measuring a harmonic distortion By activating DISTORTION a frequency can be indicated by means of the 1096 gt keys or the mouse The indicated frequency is considered the fundamental frequency The total harmonic distortion relative to this fundamental frequency is determined on the basis of the formula Dt EE KT N N IE VV Vea Me hee a Vet Vo Vio V I 20 log V is the RMS amplitude of the fundamental frequency V Vio are the RMS amplitudes of each harmonic The RMS amplitude of each harmonic is shown in a table Spectrum analyzer device SPECTRUM 53 Calculate the spectrum from the HOLD signal By activating HOLD gt FFT the spectrum of the first 1024 measuring points of the signal measured with the HOLD device is ca
44. measured waveform together with the instrument settings PRIN T MEASU REM ENT The last measured data is printed Software 23 24 MISCELLAN EO US Through this choice three choices are available ADVANCED MENU to return to the normal main menu SAVE SETTINGS to save the current instrument settings to disk QUIT PRO GRAM to quit the program Saving instrument settings lf you often use the same settings for an instrument you can save the setup on disk By loading the file with the setup you can set your instru ment very easy The setups for all five instruments are saved To save an instrument setup first you have to set the instrument comple tey After the instrument is set you can save the setup With TEXT FOR SETTINGSa dialog box appears in which three lines of explanatory text for the setup to be saved can be entered You can enter e g for what type of measurements this setup isto be used Comment text display by select settings Hith this setting channel 1 is used for measuring at a temperature probe Fi Help Ese Exit After the text is entered the dialog box is closed with lt Esc gt The popup menu SETTIN GS will become active again Choose from the menu the choice COMMENT FOR SETTINGS A dialog box appears Tenperature probe_ Fi Help Esc Exit In this dialog box a name for the setup can be entered The maximum length for the name is 25 characters This name is used for selecting the correct saved setu
45. measures the input signals at adjusta ble times The time between two measurements is adjustable from 0 01 second to 300 seconds The number of samples is also adjustable from 1 to 30000 The maximum measuring time is 300 sec x 30000 samples 9000000 seconds 104 16 days The sensitivity is adjustable between 25 mV div and 100 V div The display of the transient recorder is built of 500 x 256 wxh pixels which corresponds with 10x8 wxh divisions Left of the display the units of the channel are displayed Under the display the time axis is displayed In addition the value time and date of the samples are given The transient recorder measures in one of the following ways Chapter 1 MO MEN TAL the momentary value of the input signal is measured TRUE RMS the true RMS value of the input signal is measured MEAN the mean value of the input signal is measured MAX the maximum value of the input signal is measured MIN the minimum value of the input signal is measured Introduction 15 Chapter 1 Chapter 2 Hardware installation The Handyprobe H P2 is an external measuring instrument which can be connected to a PC The Handyprobe H P2 is connected to the parallel printer port of the PC using the attached cable Note Do not connect the H andyprobe H P2 to any other port at the PC than the Centronics parallel port Connecting to other ports may damage your H andyprobe H P2 The Handyprobe HP2 does not need an external power
46. nation with the lt Shift gt key the new position of the menu will be saved in the file HP2 D EF Chapter 3 Help screens The program contains integrated help screens The screens can be invo ked at several places in the program by pressing function key F1 The invoked help screen gives information about controlling the active program part or information about the active program part Program settings Several parts of the program are configurable To do that activate the choice SETTINGS from the main menu A popup menu will appear The contents are partly dependent on the type of graphics card in your PC If an EGA or VGA card is available two choices for setting the screen colors and the monitor type are present If no EGA or VGA card is detec ted those two choices will not be present Settings concerning the program itself and not the measuring instruments of the program are saved immediately in the file H P2 D EF which is read at the start ofthe program Setting the main menu type By using the choice SIMPLE MENU a more simple main menu containing 8 choices is selected The simple menu has the following choices MEASUREMENT TYPE W ith this a saved instrument setting can be read START STOP MEASUREMENT Stop or start the measurements REFEREN CE Show or dont show a reference signal The reference signal can be read using READ ME ASUREMENT WIPE SCREEN The signal display is cleared SAVE MEASU REM EN T The last
47. o be taken is reached While sampling the sample number the time and the measured value are displayed inverted Note When the Handyprobe HP2 is connected to a relative slow com puter it may occur that depending on the selected sampletime the sample number time and value are not being displayed O nly if enough time is available the items are displayed W hen the total measurement time is completed the window with the text disappears and the data is saved on disk Transient recorder device TRANS 67 A crosshair used for measuring now appears See the chapter oscillosco pe HOLD for information about controlling the crosshair D uring measu ring with the crosshair the value the sample number and the time of the selected sample are displayed When more than 500 samples are taken the keys lt PgUp gt and lt PgDn gt provide switching between the pages with data The current page number is displayed in the upper right corner of the screen With lt gt and lt gt the step size can be changed lt gt increases the step size lt gt decreases the step size As with the oscilloscope the data can be shifted up and down on the screen This is done in the same way as with the oscilloscope time the complete signal is read from disk which may take some Ww Note W hen switching between pages of data or shifting the signal each time Go to a specific sample By activating the GO TO choice a sample number to be
48. on for the help file HP2 FNT font file for printing output HP2 DEF file with program settings dpmil6 ovl Dos protected mode driver rtm exe protected mode run time manager An example where the diskette is in drive A and the software has to be installed in a directory called HP2 on the C drive Ce HP2 CD HP2 COPY A The software is now installed on the harddisk After starting the program the DEFAULT DIRECTORIES can be set These indicate where the pro gram has to store and look for help files instrument setting files and mea surement data files You can set the DEFAULT DIRECTORIES with the Software 19 menu SETTINGS in the lower right corner of the screen Structure of the program The program contains five integrated measuring instruments UI BU ND rnm An oscilloscope device LIVE A storage oscilloscope device HOLD A spectrum analyzer device SPECTRUM A true RMS voltmeter device VOLT A transient recorder device TRAN S O nly one measuring instrument can be active at the same time From each measuring instrument another measuring instrument can be activated Standard features of the above five measuring instruments are options to make print outs and to leave the program to return to DOS Starting the program 20 The program can easily be started according to the below mentioned procedure HP2 parl par2 If no parameters are given the device LIVE is selected with the default se
49. p when loading a setup After the name is entered the box can be closed by pressing lt Esc Chapter 3 Then activate the choice SAVE from the SETTINGS menu A dialog box appears in which the filename for the settings file can be entered The filename will automatically get an extension SET If you have entered the filename the file with the instrument setup is saved on disk To make an instrument setting which will be used as a quit program from SELECT SETTINGS menu SETTIN GS from the advance main menu or MEASUREMENT TYPE simple menu any instrument setup will do but the filename for the settings has to be QUIT If a file named QUIT is read by one of the two here mentioned menus the program will quit Reading that file using RESTO RE will not quit the program Loading instruments settings Saved instrument settings can be read in three ways at the start of the program as a parameter through the choice RESTORE from the SET TINGS menu and through the choice SELECT SETTINGS from the SETTIN GS menu The first method is already mentioned on page 23 After activating the choice RESTO RE a popup menu with a list of the pre sent settings files appears By means of the lt 6 1 89 gt keys the file to be loaded can be selected By pressing lt Enter gt the selection is accepted Before loading an extra confirmation is requested The selection can be cancelled by pressing Esc After activating the choice SELECT SETTING
50. rough It is then possible to examine e g a 20 mV ripple on a 30 V DC voltage since only the ripple is passed through and the DC volta ge not AC voltages with a frequency lower than 4 Hz are not coupled correctly The current coupling is displayed in the upper part of the vertical axis For DC the sign z is used and for AC the sign Setting the vertical position The vertical position ofthe channel on the screen can be adjusted W hen doing this the signal is shifted graphically after sampling This me thod only has an effect on the displayed signal If the signal clipped because it is larger than the selected input range and is positioned with the softwa re method the signal remains clipped but the clipping is now visible on the display The signal appears to be cut off at either the upper side or the lower side The positioning method is not done by means of a popup menu At the lefthand side of the screen two small arrows are visible The small arrow next to the border ofthe window isfor the position of a channel the outer arrow isfor the trigger level which is discussed later 5 00 5 00 Only one offset arrow can be active displayed normally The other arrow is displayed inverted In the latter illustration the channel offset ar row is active Oscilloscope device live hold 33 34 The arrow indicates the offset the 0 volt level The offset can be set as follows Note To change the offset firs
51. s referred to the chapter O scilloscope LIVE The HOLD scope only worksin ONE SHOT mode and does not measure 2 but 30 pages of 500 samples With the lt PgUp and lt PgDn keys the pages are selected The step size can be set using the lt gt or lt gt keys The HOLD scope can store data on disk while measuring The main menu ofthe HOLD device differs slightly from the main menu of the LIVE device At the position where in the LIVE device the LIVE FREE ZE choice is found the HOLD device hasa choice O N E SHOT Automatic storage of measurement data The storage oscilloscope can store measurement data automatically on disk This is set by activating the choice NO DISK from the main menu The text changes from N O DISK to AUTO DISK As soon as a measure ment is started using O N E SHOT entering a filename for the data is re quested Syntax drive Spathsfilename no ext DATA 1 Fi Help Enter Accept Esc Exit For the name 5 characters are accepted the rest is ignored The software adds three characters for a file serial number When the name is entered measuring can start There is a delay until the input signal meets the trigger conditions When the trigger conditions have been met and a signal is measured the data is written on disk This is indicated by a text window in the lower left corner ofthe screen Storage oscilloscope device HOLD 43 aa W hen the data measurement data time an
52. sta declaraci n es v lida est en relaci n con EN 55011 EN 55022 EN 50081 1 y EN 50082 1 Seg n las condiciones del EMC est ndar 89 336 EEC y los movimientos 92 31 EEC y 93 68 EEC Sneek 1 9 1999 ir A P W M Poelsma TiePie engineering Kopeslagersstraat 37 8601 WL Sneek The Netherlands EC Hyv ksynt ilmoitus Velvollisuutenamme on ilmoittaa ett tuotteemme Handyprobe HP2 jota t m selvitys koskee on huv ksytty EN 55011 EN 55022 EN 50081 1 ja EN 50082 1 EMC standardien 89 336 EEG ja lis standardien 92 31 EEC ja 93 68 EEC mukaisesti ir A P W M Poelsma Me Sneek 1 9 1999 Chapter 1 Introduction D Note before using the Handyprobe HP2 first read the chapter about Safety Many technicians investigate electrical signals Though the measurement may not be electrical the physical variable is often converted to an electri cal signal with a special transducer Common transducers are acceler ometers pressure probes current clamps and temperature probes The advantages of converting the physical parameters to electrical signals are large since several instruments for examining electrical signals are availa ble The Handyprobe H P2 is a one channel 8 bits 1 20 Msamples sec mea suring instrument W ith the acompanying software the H andyprobe H P2 can be used as an oscilloscope a storage oscilloscope a spectrum analy zer atrue RMS voltmeter or a transient recorder All instruments meas
53. supply but is powered by the computer Note Switch to avoid damage at the H andyprobe H P2 or the computer before connecting the cable the computer off If your computer is equipped with one parallel printer port a conflict may arise when printing waveforms The Handyprobe HP2 has to be discon nected from the PC and the printer be connected to the PC Then the print job can be finished After that the printer has to be disconnected and the H andyprobe H P2 hasto be connected to the PC again Note Place to avoid much switching between printer and H andyprobe HP2 an extra printer port in your PC Hardware installation 17 Chapter 2 Chapter 3 Software Installation of the software The software of the H andyprobe H P2 is shipped on one diskette First you have to make a backup of the original diskette Refer to your DOS manual for making a backup of a diskette W hen you have made the backup store the original diskette in a safe place and use the backup The software is shipped ready to use without installation program You can run the software direct from the diskette or from a hard disk Hint A hard disk is much faster than a diskette and has usually more free space available to store data To install the software on a hard disk first make a directory for the softwa re Then copy all files from the diskette to the directory The files are HP2 EXE the program HP2 ENG HIP the English help file HP2 ENG INF informati
54. t remove all popup menus Move the offset level up Move the offset level down Move the offset level to the center Select the next offset or trigger level Select the previous offset or trigger level Move the offset level to the top Move the offset level to the bottom Increase the step size 2 times Decrease the step size 2 times hl Ben OT TDA Switching between crosshair controll and offset trig Q Q 000 000 DI ger level controll Note the step size for changing the offset level or trigger level can be changed with lt Shift gt and lt Shift gt The offset level can also be changed with the mouse Place the mouse cursor on top ofthe arrow ofthe offset level to be changed and drag it to the correct position Drag press the left mouse button and keep it pres sed while moving the mouse W hen the arrow is at the correct position release the mouse button The mouse cursor will disappear while dragging the arrow and appear again when the button is released Enlarging or reducing the vertical axis The measured values can be enlarged or reduced by software Because of that it is possible to magnify the vertical axis It is also possible to invert the measured values After activation of the choice GAIN in the menu CH SET a dialog box appears in which a multiplication factor can be entered The factor must be between 5 0 1 or 0 1 5 The measured factors are multiplied by the factors and then displayed The num
55. th these 1024 samples here called FFT block the spectrum is calculated Therefore the FFT places an infinite number of FFT blocks behind each other in the positive and negative direction Each FFT block forms 1 period of the created periodic signal lt lt gt gt periodic extension measured FFT block periodic extension gt t FFT block i 1024samples FFT block From the signal obtained like this the spectrum is calculated The FFT calculation results in 512 spectral components These spectral compo nents together form the frequency spectrum ofthe input signal 500 ofthe 512 spectral components are displayed in 12 divisions of 40 spectral components each Spectrum analyzer device SPECTRUM 45 The Handyprobe H P2 spectrum analyzer displays an amplitude spectrum which means that a 2 volt peak peak sine wave is displayed with a 1 volt spectral component Aliasing Like the oscilloscope the spectrum analyzer needs a high enough sampling frequency to avoid aliasing The result of aliasing when using FFT is that the frequency curve is folded back on itself See also the next illustration Amplitude alias function true transformation o ZE The original signal is sampled at a sample time A The critical frequency N yquist frequency is 1 2A Hz Windowing FFT treats the FFT block of 1024 samples like it is one period of a periodic signal If the sampled signal is not periodic
56. the right mouse button if no other menu is active Chapter 3 Chapter 4 Oscilloscope device LIVE An oscilloscope is a measuring instrument which displays the changes of a voltage in the time domain The Handyprobe HP2 is equipped with an oscilloscope with a fully confi gurable input channel It is a digital sampling oscilloscope That means that the oscilloscope takes samples at fixed times From each sample the value is determined and the size is displayed at the screen The screen is filled with 500 samples per channel Between two adjacent samples on the screen aline is drawn The speed at which the samples are taken is adjus table Aliasing A disadvantage of digital sampling oscilloscopes is the fact that aliasing can occur Aliasing occurs when too low and therefore a wrong sampling speed is chosen In the next illustration is shown how aliasing occurs Oscilloscope device live hold 31 The input signal is a triangular signal with a frequency of 1 25 kHz upper most in the illustration The signal is sampled at a frquency of 1 kHz The dotted signal is the result of the reconstruction From that triangular signal the periodical time is 4 ms which corresponds with an apparent frequency alias of 250 Hz 1 25 kHz 1 kHz To avoid aliasing the sample frequency must be greater than 2 times the maximum frequency of the input signal If you have any doubts about the displayed signal you can set the t
57. tivating the FREQUENCY choice a popup menu appears display ing 7 center frequencies A frequency range is determined from 0 2 x f to 10 XT en For example when 50 Hz is choosen signals with a frequency between 10Hzto 500 Hz will be calculated correctly The following center frequencies can be selected 10 Hz 50 Hz 100 Hz 500 Hz 1 kHz 5 kHz 10 kHz 50 kHz and 100 kHz Perform measurements 62 By activating the MEASURE FREEZE choice from the main menu the text in the menu changes from M EASU RE to FREEZE or vice versa In the MEASURE position 200 sample values are taken and from that a determined quantity will be calculated The quantity to be determined can be set with the CH SET menu MEASURIN G option The last measured values are displayed in the FREEZE position By activating the choice ONE SHOT from the main menu one measure ment is taken and from that the data will be calculated and displayed This menu is only available when the M EASU RE FREEZE choice is in the FREEZE position Note A measurement consists of three succuessive measurements which are averaged In between these measurements the display is upda ted If the voltmeter has to perform an auto range while measuring in one shot as much as nesessary measurements are taken until three measurements are taken in the final input range Chapter 7 Storing measurement values on disk or paper The voltmeter can store measurement values on disk or print them
58. ttings The parameters Dar and par2 have the following meaning par c c5 c5 c c par2 Indicates the device that will be activated after starting the program Valid values are LIVE Measuring instrument oscillosco pe HOLD i Measuring instrument storage oscilloscope SPECTRUM Measuring instrument spectrum analyzer VOLT Measuring instrument true RMS voltmeter TRANS Measuring instrument transient recorder Indicates the filename of the instrument setting see for writing or reading instrument settings SETTIN GS menu Chapter 3 Example HP2 trans b HP set means the measuring instrument transient recorder is activated with the file settings b H P set Incorrect instrument or filenames will be ignored The parameters parl and par2 may be exchanged sequentially but have to be separated by a space Controlling the program After starting the program first an intro screen with program information is displayed This screen indicates what kind of display adapter the program has detected and whether a Microsoft compatible mouse is available After the intro screen has disappeared the normal working screen appe ars This screen is divided in two parts a part for displaying the measure ment data and apart for the main menu for controlling the program The program can be controlled by the keyboard as well as by a mouse Controlling by mouse W hen using the mouse the left mouse button is used for Enter and
59. ture change is displayed directly in the number of degrees It is also possible to add an offset to the numbers of the vertical axis In the dialog box called by activating OFFSET from the CH SET menu an offset can be entered This offset is added to the numbers along the vertical axis N othing is done to the signal Oscilloscope device live hold 35 An aplication for this is again the temperature measurement Suppose the output voltage of the temperature probe at 0 C is 10 Volt By enteringa UNITS O FFSET of 10 the zero level of the axis is changed in a way that the absolute temperature is directly readable Setting up the time axis 36 Along the horizontal axis of the screen the measuring time is projected The oscilloscope always measures 2 pages of samples Default the page after the trigger point is displayed post trigger Switching between the 2 pages is done by pressing lt PgU p or lt PgDn gt lt PgUp gt gives the post trigger page and lt PgDn gt gives the pre trigger page The keys lt gt and lt gt can be used to adjust the step size Setting the timebase By activating the choice TIME DIV a popup menu appears displaying 12 time ranges When for example the 0 2 sec choice has been activated one time division will be equal to 0 2 sec The screen contains 10 time divisions O ne time division consists of 50 samples The screen contains 10 50 500 sample values By activating the 0 2 sec choice one
60. uency has been selected the minimum sampling time will be 1 5 sec Setting the sampling time GE SE 66 By activating SAMPLE TIME the sampling time between two measured values can be given For the sampling time a value between 0 01 and 300 sec can be given Then the total measuring time can be 300 30 000 9 000 000 sec 104 16 days Note OnaPC XT the minimum sampling time is 0 05 sec Note When no momentary values are taken see MEAS MODE the minimum sampling time is 0 5 sec or 1 5 sec at a frequency setting of 10Hz Chapter 8 Setting the number of samples By activating the SAMPLES menu the number of samples can be given For the number of samples a value between 1 and 30 000 can be given Then the total measuring time can be 300 30 000 9 000 000 sec 104 16 days Clear the screen By activating the CLEAR SCR choice the screen of the transient recor der is erased Start a measurement When all settings are set a measurement can be started by activating MEASURE from the main menu First aname has to be entered for the file the data will be stored in If the name of an existing file is entered you will be asked whether this file can be overwritten by the new data The old data will be destroyed When the name is entered sampling starts This is indicated by a win dow with the text EASURING Esc interrupt measuring At fixed times a sample is taken until the number of samples t
61. uency range of the spectrum analyzer goes from 0 025 Hz to 10 MHz The display of the spectrum analyzer is built of 500 x 256 wxh pixels which corresponds with 10x8 wxh divisions Left of the display the units of the channel are displayed Under the display the frequency axis is dis played The voltmeter If from the input signals only the size is important and not time information or frequency components the voltmeter is a suitable instrument to mea Introduction 13 sure with The voltmeter measures the size of the input signal and displays the values using a large 7 segment display The voltmeter can measure the input signal in several ways TRUE RMS the true RMS value is measured PEAK PEAK the peak peak value is measured MEAN the mean value is measured MAX the maximum value is measured MIN the minimum value is measured dBm the value is gven in decibel POWER the power of the input signal is determined CREST the crest factor is calculated FREQ the frequency of the input signal is measured The input of the voltmeter is autoranging or manually settable between 500 mV full scale and 400 V full scale Besides this the voltmeter has the possibility to measure at certain times and send the data to a printer or write it on disk The transient recorder For measuring slowly changing signals e g the temperature change in a room the transient recorder is the most suitable instrument The two channel transient recorder
62. ure by sampling the input signals digitizing the values process them save them and display them Sampling W hen sampling the input signal samples are taken at certain moments The frequency at which the samples are taken is called the sampling fre quency By taking a large number of samples the input signal can be reconstructed Introduction 9 In the latter illustration a sine wave signal is sampled with 50 samples By connecting the adjacent samples the original signal can be reconstructed See also the next illustration The more samples are taken the better the signal can be reconstructed The sampling frequency must be higher than 2 times the highest frequency in the input signal This is called the N yquist frequency Theoretically it is possible to reconstruct the input signal with more than 2 samples In prac tice 10 to 20 samples are necessary to be able to examine the signal thoroughly Aliasing If the sampling frequency is lower than 2 times the frequency of the input signal aliasing will occur The following illustration shows how aliasing Tn 08ms 1 1 1 1 1 1 E E Tappert 4 Y lt appare me gt The input signal is a triangular signal with a frequency of 1 25 kHz upper Chapter 1 most in the illustration The signal is sampled at a frequency of 1 kHz The dotted signal is the result of the reconstruction From that triangular signal the periodical time is 4 ms which
63. ured to your own demands By activating the choice UNIT a popup menu with the choices W hen the requested option is activated this unit will be placed under the display behind the MEASURING mode At an ACQUIRE TO DISK or an ACQUIRE TO PRINTER the unit is placed behind the MEASURIN G mode as well Voltmeter device VOLT 59 60 Changing the units per volt By activating the choice UNITS VOLT you can enter a factor for the display The value filled in will be multiplied with the measured value Example A thermocouple generating 1 volt per 5 degrees is measured Then the number of UNITS VOLT can be set at 5 allowing the direct reading of the correct number of degrees When an oscilloscope probe which attenuates 10 times is used the value 10 can be entered with the UN ITS VO LT option so the correct voltage values can be read directly Relative measurements By activating the RELATIVE ON OFF choice the text changes from RELATIVE ON to RELATIVE OFF or vice versa The RELATIVE ON option results in decreasing the displayed value with the value given at the SET REL VALUE option Example MEASURING is set on MEAN and DISPLAY is set on CH1 When a DC voltage of 10 volt is offered the voltmeter will point at 10 volt When the value 10 is filled in with the SET REL VALUE option and RELATIVE ON is set the voltme ter will point at 0 volt With the RELATIVE OFF option the measured value is not influenced Comparison

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