JN3 Hardware User Guide
Contents
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4. wand ot y D J s j Ai pe a Fag lt Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 31 of 32 el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 13 Document History Revision Date Changes Firstissve Updated Figure 1 Updated Figure 3 main serial port section and mems section by gt f oen lt 3 Gi 2 is A 2 T Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 32 of 32 RET dB I ARETAN SE maB http Wwww edatop com HAMARAKTRIRA EH eS www edatop com 2006 EDA www mweda com MUREM ADS HFSS
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6. If the GPS antenna is placed near the JN3 and the RF traces losses are not excessive nominally 1 dB then a passive antenna can be used This would normally be the lowest cost option and most of the time the simplest to use However if the antenna needs to be located away from the JN3 then an active antenna may be required to obtain the best system performance The active antenna has its own built in low noise amplifier to overcome RF trace or cable losses after the active antenna However an active antenna has a low noise amplifier LNA with associated gain and noise figure In addition many active antennas have either a pre select filter a post select filter or both RF Trace Losses RF Trace losses are difficult to estimate on a PCB without having the appropriate tables or RF simulation software to estimate what the losses would be A good rule of thumb would be to keep the RF traces as short as possible make sure they are 50 ohms impedance and don t contain any sharp bends Implications of the Pre select SAW Filter The JN3 module contains a SAW filter used in a pre select configuration with the built in LNA that is the RF input of the JN3 ties directly into the SAW filter Any circuit connected to the input of the JN3 would see complex impedance presented by the SAW filter particularly out of band rather than the relatively broad and flat return loss presented by the Reproduction forbidden without written authorization fr
7. Teli JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 wireless solutions R ar Yas a gt 4 a ta trirta nu a 7 i wad Making machines talk 7 e Telit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 APPLICABILITY TABLE PRODUCT Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 2 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE Notice While reasonable efforts have been made to assure the accuracy of this document Telit assumes no liability resulting from any inaccuracies or omissions in this document or from use of the information obtained herein The information in this document has been carefully checked and is believed to be entirely reliable However no responsibility is assumed for inaccuracies or omissions Telit reserves the right to make changes to any products described herein and reserves the right to revise this document and to make changes from time to time in content hereof with no obligation to notify any person of revisions or changes Telit does not assume any liability arising out of the application or use of any product software or circuit described herein neither does it convey license under its patent rights or the rights of others It is possible that this publication may contain
8. 08 06 Ak RF Signal Requirements The JN3 can achieve Cold Start acquisition with a signal level of 147 dBm at its input This means the JN3 can find the necessary satellites download the necessary ephemeris data and compute the location within a 5 minute period In the GPS signal acquisition process downloading and decoding the data is the most difficult task which is why Cold Start acquisition requires a higher signal level than navigation or tracking signal levels For the purposes of this discussion autonomous operation is assumed which makes the Cold Start acquisition level the important design constraint If assistance data in the form of time or ephemeris aiding is available then even lower signal levels can be used to compute a navigation solution The GPS signal is defined by IS GPS 200E This document states that the signal level received by a linearly polarized antenna having 3 dBi gain will be a minimum of 130 dBm when the antenna is in the worst orientation and the satellite is 5 degrees or more above the horizon In actual practice the GPS satellites are outputting slightly more power than specified by IS GPS 200E and the signal level typically goes higher as the satellites have higher elevation angles The JN3 will display a reported C No of 40 dB Hz for a signal level of 130 dBm into the RF input Each GPS satellite presents its own signal to the JN3 and best performance is obtained when the signal levels are between 1
9. Party supplied computer programs stored in semiconductor memories or other media Laws in the Italy and other countries preserve for Telit and other 3rd Party supplied SW certain exclusive rights for copyrighted computer programs including the exclusive right to copy or reproduce in any form the copyrighted computer program Accordingly any copyrighted Telit or other 3rd Party supplied SW computer programs contained in the Telit products described in this instruction manual may not be copied reverse engineered or reproduced in any manner without the express written permission of Telit or the 3rd Party SW supplier Furthermore the purchase of Telit products shall not be deemed to grant either directly or by implication estoppel or otherwise any license under the copyrights patents or patent applications of Telit or other 3rd Party supplied SW except for the normal non exclusive royalty free license to use that arises by operation of law in the sale of a product Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 3 of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Usage and Disclosure Restrictions License Agreements The software described in this document is the property of Telit and its licensors It is furnished by express license agreement only and may be used only in accordance with the terms of such an agreement Copyrighted Materials Softwar
10. Scope The JN3 is a 12 1mm by 15 9mm integrated GPS receiver module using SiRFstar IV technology This document expands upon the data sheet s to highlight particular areas to allow the hardware engineer to achieve a successful design implementation 1 2 Audience This document Is intended for helping customer in the integration of the Telit SL868 GPS module 1 3 Contact Information Support For general contact technical support to report documentation errors and to order manuals contact Telit Technical Support Center TTSC at TS EMEA telit com TS NORTHAMERICA telit com TS LATINAMERICA telit com TS APAC telit com Alternatively use http www telit com en products technical support center contact php For detailed information about where you can buy the Telit modules or for recommendations on accessories and components visit http www telit com To register for product news and announcements or for product questions contact Telit Technical Support Center TTSC Our aim is to make this guide as helpful as possible Keep us informed of your comments and suggestions for improvements Telit appreciates feedback from the users of our information 7 L 7 a 2 2 F S js fe gt 7 F F gt 27 f pp A ADAG i i Gi j b a Sa A ESS y Wy D af n 3 best Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 7 o
11. ae esses ce se waves c ocean rene sc a cece ese sare ucaseedeaucine suck osnteueteaneiseseces 22 9 Firmware Configuration nt 23 9 1 Internal LNA ccc eccc ce ecceeceeeeeaeeeeeeeeeeaeecesaeeeaeeeeeaeeceeaeeceseeeeeaeecesaneeteaeeeaeeenanes 23 9 2 TricklePower Low Power Mode ccccecseccseseessesecercetserecsecereesecreessesssireesterecertnseesees 23 93 ONkoenallileaee om ee E a ee ene ae eee 24 93 1 NMEA Protocol Considerations snd a 24 932 OSP Considera ONS oe ene een ee en ene eee ener eter ener nen eee een en eee eee 24 9 4 MEMS Configuration nn 24 95 Moton D IN CS cscs oacetecten co cenaev tare accierwaa vs oy chattel AEEA TT E ESE aa NNE NE 29 ae DO 25 9 5 2 Velocity Dead Reckoning er 25 953 3 MEMS Static D tecHO ee na adi 25 954 MEMS W es 20 9 6 Advanced Features pp 26 90 CW Jamming Detection ee 26 9 6 2 20 0 0D 26 9 04 MEMS Compass Heading pp 27 10 Handling and soldering ccc cccc cece cece e cence eee ececenencececeneaceceneneetenseceneas 28 JRO ame NONURSGIRIWI ene ne ee ee EEE 28 29 LU AL 29 IOA AN eS 29 ll PCB Layout Details ee eee eae 30 12 Safety Recommendations 4 31 13 Document History pp 32 A a5 3 I peso s a i lt the a rane a Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 6 of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 1 Introduction 1 1
12. below The solder mask opening is generally determined by the component geometry of other parts on the board and can be followed here Standard industry practice is to use a paste mask stencil opening the same dimensions as the pad design All dimensions shown are in mm Aj Figure 3 JN3 Pad Design TOP View pear sduel ti forbidden without written ao eon from Telit Communications S p A All Rights Reserved Page 30 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 12 Safety Recommendations READ CAREFULLY Be sure the use of this product is allowed in the country and in the environment required The use of this product may be dangerous and has to be avoided in the following areas e Where it can interfere with other electronic devices in environments such as hospitals airports aircrafts etc e Where there is risk of explosion such as gasoline stations oil refineries etc It is responsibility of the user to enforce the country regulation and the specific environment regulation Do not disassemble the product any mark of tampering will compromise the warranty validity We recommend following the instructions of the hardware user guides for a correct wiring of the product The product has to be supplied with a stabilized voltage source and the wiring has to be conforming to the security and fire prevention regulations The product has to be handled with care avoiding any contact with the pin
13. directly overhead they should supply antenna pattern curves specifying gain as a function of elevation and gain at a fixed elevation as a function of azimuth Pay careful attention to the requirement to meet these specifications such as ground plane required and any external matching components Failure to follow these requirements could result in very poor antenna performance It is important to note that GPS antenna gain is not the same thing as external LNA gain Most antenna vendors will specify these numbers separately but some combine them into a single number It is important to know both numbers when designing and evaluating the front end of a GPS receiver For example antenna X has an antenna gain of 5 dBiC at azimuth and an LNA gain of 20 dB for a combined total of 25 dB Antenna Y has an antenna gain of 5 dBiC at azimuth and an Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 17 of 32 7 4 IDs 7 6 Tals s i gt g 2 a wm Fa if 4 i n 3 2 7 p ot sa an 5 h j 7 fs F f tgi d At 0 2 Bs i iis P i E wA f s r i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 LNA gain of 30 dB for a combined total of 25 dB However in the system antenna X will outperform antenna Y by about 10 dB refer to Section 7 4 for more details on system noise floor An antenna with higher
14. gain will generally outperform an antenna with lower gain Once the signals are above about 130 dBm for a particular satellite no improvement in performance would be gained However for those satellites that are below about 125 dBm a higher gain antenna would improve the gain and improve the performance of the GPS receiver In the case of really weak signals a good antenna could mean the difference between being able to use a particular satellite signal or not System Noise Floor As mentioned earlier the JN3 will display a reported C No of 40 dB Hz for an input signal level of 130 dBm The C No number means the carrier or signal is 40 dB greater than the noise floor measured in a one Hz bandwidth This is a standard method of measuring GPS receiver performance Thermal noise is 174 dBm Hz at around room temperature From this we can compute a system noise figure of 4 dB for the JN3 This noise figure consists of the loss of the pre select SAW filter the noise figure of the LNA as well as implementation losses within the digital signal processing unit If a good quality external LNA is used with the JN3 then the noise figure of that LNA typically better than 1dB could reduce the overall system noise figure of the JN3 from 4 dB to around 2 dB Some of the factors in the system noise figure are implementation losses due to quantization and other factors and do not scale with improved front end noise figure Active versus Passive Antenna
15. will have 3 dB loss as compared to an RHCP antenna assuming the same antenna gain specified in dBi and dBic respectively An RHCP antenna is better at rejecting multipath than a linearly polarized antenna This is because the reflected signal changes polarization to LHCP which would be rejected by the RHCP antenna by typically 20 dB or so If the multipath signal is attenuating the line of sight signal then the RHCP antenna would show a higher signal level than a linearly polarized antenna because the interfering signal is rejected However in the case where the multipath signal is replacing the line of sight signal such as in an urban canyon environment then the number of satellites In view could drop below that needed to determine a 3D solution This is a case where a bad signal may be better than no signal The system designer needs to make tradeoffs in their application to determine which is the better choice 7 3 GPS Antenna Gain Antenna gain is defined as the extra signal power from the antenna as compared to a theoretical isotropic antenna equally sensitive in all directions For example a 25mm by 25m square patch antenna on a reference ground plane usually 70mm by 70mm will give an antenna gain at zenith of 5 dBic A smaller 18mm by 18mm square patch on a reference ground plane usually 50mm by 50mm will give an antenna gain at zenith of 2 dBic While an antenna vendor will specify a nominal antenna gain usually at zenith or
16. 1 Note that a data message is output for each sensor and can contain several sets of data from the given sensor P Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 24 of 32 9 5 JS 9 5 2 9 5 3 Reproduction forbidden without written authorizatio i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Motion Dynamics Static Navigation Static navigation also called position pinning is a mechanism that it is used by the receiver to freeze or pin the position when the velocity falls below a threshold indicating that the receiver is stationary The heading is also frozen and the velocity is reported as 0 The solution is then unpinned when the velocity increases above a threshold or when the computed position is a set distance from the pinned position indicating that the receiver is in motion again Note that these velocity and distance thresholds cannot be changed By default static navigation is disabled It can be enabled by sending a Static Navigation message Message ID 143 with the static navigation flag set to 1 This feature is useful for applications in which very low dynamics are not expected the classic example being an automotive application Velocity Dead Reckoning Velocity dead reckoning refers to the use of the last known velocity to propagate the navigation solution when there are insufficient measurements to calculate an update
17. 10 3 Reflow The JN3 is compatible with lead free soldering processes as defined in IPC JEDEC J STD 020 The reflow profile must not exceed the profile given IPC JEDEC J STD 020 Table 5 2 Classification Reflow Profiles Although IPC JEDEC J STD 020 allows for three reflows the assembly process for the JN3 uses one of those profiles Thus the JN3 is limited to two reflows Note JEDEC standards are available for free from the JEDEC website http www jedec org When reflowing a dual sided SMT board it is important to reflow the side containing the JN3 module last This prevents heavier components within the JN3 becoming dislodged if the solder reaches liquidus temperature while the module is inverted 10 4 Assembly Issues Due to the piezo electric components within the JN3 the component should be placed close to the end of the assembly process to minimize shock to the module During board singulation pay careful attention to unwanted vibrations and resonances introduced into the board assembly by the board router 7 d sf 4 F S Po fe 4 te F J gt F srg A Sy FS i 7 f s 2 Wp ms pi gt y 7 1 TREE Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 29 of 32 el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 11 PCB Layout Details The PCB footprint on the receiving board should match the JN3 pad design shown
18. 25 dBm and 117 dBm These received signal levels are determined by e GPS satellite transmit power e GPS satellite elevation and azimuth e Free space path loss e Extraneous path loss such as rain e Partial or total path blockage such as foliage or building e Multipath caused by signal reflection e GPS antenna e Signal path after the GPS antenna The first three items in the list above are specified in IS GPS 200E readily available multiple sources online IS GPS 200E specifies a signal level minimum of 130 dBm will be presented to the receiver when using a linearly polarized antenna with 3 dBi gain The GPS signal is relatively immune to rainfall attenuation and does not really need to be considered However the GPS signal is heavily influenced by attenuation due to foliage such as tree canopies etc as well as outright blockage caused by building terrain or other items in the line of sight to the specific GPS satellite This variable attenuation is highly dependent upon GPS satellite location If enough satellites are blocked say at a lower elevation or all in a general direction the geometry of the remaining satellites will result is a lower accuracy of position The JN3 reports this geometry in the form of PDOP HDOP and VDOP For example in a vehicular application the GPS antenna may be placed embedded into the dashboard or rear package tray of an automobile The metal roof of the vehicle will cause significant blockage plus
19. 8V 3 axis accelerometer can be used The interrupt output of the accelerometer must be connected to GPIO4 of the JN3 Data for the approved magnetic sensor Aichi Steel part number AIM304 3 5 x 4 0mm 3V 3 axis magnetometer is output in OSP message 72 i e gt A E A aor i i 4 ry K gt Wd 2 Bir a f A TE 5 i f F pi ba S 7 n a Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 14 of 32 T RF Front End Design l el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 The JN3 contains an integrated LNA and pre select SAW filter This allows the JN3 to work well with a passive GPS antenna If the antenna cannot be located near the JN3 then an active antenna that is an antenna with a low noise amplifier built in can be used The following items will be discussed in turn to assist in designing the RF front end l CO NAKAAKR WN RF signal requirements GPS antenna polarization GPS antenna gain System noise floor Active versus passive antenna RF trace losses Implications of the pre select SAW filter External LNA gain and Noise Figure Powering the external LNA active antenna 10 RF interference 11 Shielding Reproduction biden without written ao eon from Telit Communications S p A All Rights Reserved Page 15 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012
20. Some event or alarm messages occur spontaneously and cannot be directly controlled You must assess the capacity of the communications link between JN3 and the host You must select OSP or NMEA messages appropriate to the application and well within the maximum capacity of the communications link In assessing the capacity required consider the protocol overheads and maximum size of variable payloads In power consumption critical applications any time spent creating and sending messages causes both the JN3 and the host to consume power A low data link speed extends the current consumption of both host and JN3 TX RX Electrical e 1 mark is logic high e 0 space is logic low e idle line logic high e Line break open line is continuous logic low Continuous break is not allowed on RX during operation and not generated on TX during operation e Do not drive the RX line HIGH if no power is applied to the module Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 13 of 32 el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 6 MEMS Sensor EEPROM Interface The DR I2C port is used for connecting to MEMS sensors such as accelerometer or magnetometer Pullup resistors of approximately 2 2Kohm to 1 8 volts are required on the SCL2 and SDA2 lines for proper operation Only an approved accelerometer KIONIX part number KXTF9 4100 3 x 3mm LGA 1
21. a power down condition The reset also forces the JN3 into a keep alive power state While this means the JN3 can work with a main supply voltage down to 2 5 volts DC the 3 3 volt DC logic levels on the module output will also be scaled proportionally The JN3 module always powers up into the operate state without user intervention Za Battery Back up VBATT is applied to the module to keep the RTC running and battery backed RAM alive whenever main power is removed This allows for faster startup upon reapplication of main power If main power is removed the flash based modules will draw approximately 40 uA from the input whereas the EEPROM based modules will draw approximately 110 uA and the ROM only devices will draw approximately 110 uA Internal diode OR ing provides an internal source for VBATT even if this pin is not used F a gt gt N z Le as j ee i 27 agp 2 n 0 i ne E i Eee SHA F lt m 7 d 5 E lt P f i m i ii j A 74 f eg F AD i p J gt a y mE f s 2S em Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 10 of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 3 Updating the Firmware Flash Module ONLY During normal operations the BOOT signal should be tied to ground through a 100K pulldown resistor This will ensure the GPS module executes the code out of the internal fla
22. any thermal coating applied to the vehicle glass can attenuate the SN Wm 1 i f Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 16 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 GPS signal by as much as 15 dB Again both of these factors will affect the performance of the receiver Multipath is a phenomena where the signal from a particular satellite is reflected and is received by the GPS antenna in addition to or in place of the original line of sight signal The multipath signal has a path length that is longer than the original line of sight path and can either attenuate the original signal or if received in place of the original signal add additional error in determining a solution because the distance to the particular GPS satellite is actually longer than expected It is this phenomena that makes GPS navigation in urban canyons narrow roads surround by high rise buildings so challenging In general the reflecting of the GPS signal causes the polarization to reverse The implications of this are covered in the next section 2 GPS Antenna Polarization The GPS signal as broadcast is a right hand circularly polarized signal The best antenna to receive the GPS signal is a right hand circularly RHCP polarized antenna Remember that IS GPS 200E specifies the receive power level with a linearly polarized antenna A linearly polarized antenna
23. ches are retrieved from EEPROM and loaded into patch RAM Firmware patches are accumulated into patch data files which in turn are made available with descriptions of their contents and applicability A patch data file 1s cumulative in that it includes firmware improvements and enhancements made available in previous patches It may also include configuration settings that differ from the ROM defaults as in the default UART baud rate for example The desired patch data file must be distributed to the end user device where it may be accessed by the Host processor The Host processor in the end user device is required to run software that sends patch data from the patch file to the module using OSP Patch Protocol messages over the host serial port Example source code to assist in the implementation of a patch downloader on the Host processor is available Note that the module must be operating in full power mode during the patching process The patch contents are loaded into patch RAM on the module where they remain as long as main power is maintained This avoids the reloading of patches into patch RAM when the system resumes normal operation from a low power state such as hibernate At the end of the patching process the module performs an internal reset and restart If main power is lost on the ROM only module the Host processor must re send the patch data over the host serial port after the module is powered up The Host processor can determine w
24. d solution It serves to mitigate the effects of blocked satellite signals by continuing to provide a position output Note that the receiver outputs status information which indicates whether a solution is being maintained using dead reckoning By default the receiver operates in dead reckoning mode for up to 15 seconds before invalidating the position This timeout value is considered to be appropriate for most applications It can be changed using the Mode Control message Message ID 136 Valid timeout values range from zero which disables dead reckoning to two minutes MEMS Static Detection MEMS Static Detection uses 3 axis accelerometer data to constrain position drifts and wander during stationary periods of operation MEMS Static Detection is an improvement over the Static Navigation method because the accuracy of the accelerometer data is not a function of the dynamics of the receivers or the signal level of the GPS satellites T7 G Ae os i A i Ti gt TE a 3 sa i 2 Ba g BL Pee Py aa T 4 m A TENERNE n from Telit Communications S p A All Rights Reserved Page 25 of 32 9 5 4 9 6 9 6 1 9 6 2 9 6 3 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 MEMS Wake up MEMS Wake up also uses a 3 axis accelerometer to determine if the receiver is moving or not Currently this is only a sub feature of MPM not a stand alone feature In this feat
25. e and documentation are copyrighted materials Making unauthorized copies is prohibited by law No part of the software or documentation may be reproduced transmitted transcribed stored in a retrieval system or translated into any language or computer language in any form or by any means without prior written permission of Telit High Risk Materials Components units or third party products used in the product described herein are NOT fault tolerant and are NOT designed manufactured or intended for use as on line control equipment in the following hazardous environments requiring fail safe controls the operation of Nuclear Facilities Aircraft Navigation or Aircraft Communication Systems Air Traffic Control Life Support or Weapons Systems High Risk Activities Telit and its supplier s specifically disclaim any expressed or implied warranty of fitness for such High Risk Activities Trademarks TELIT and the Stylized T Logo are registered in Trademark Office All other product or service names are the property of their respective owners Copyright Telit Communications S p A 2012 2 4 5 a lt F n fe J y n i gt p y f iv A Ade Di 4 4 et lt wag Fa Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 4 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Contents 1 Introduction 22 ccc cece eee en
26. e nce c eee c ete n ease caencecececenenenenceceteceneneaeaeaeseneenes 7 L006 E A A E E nas 7 7 Lo Contact INTOMMATION SUPPOME so ee 7 1 4 Document Organization ns 8 Lo T one miO aora aE EAE TE EO 8 Lo Raa IOC MS SS 9 2 Powerme CNC IND orc ess cece pect neg oe se een EE ocd eee 10 ol Voy VOSS SS 10 2 DURBI E Aa E EE 10 3 Updating the Firmware Flash Module ONLY pp 11 4 Updating Patch Code EEPROM and ROM modules with Host Memory 12 5 Main Serial Interface 4 13 Sr 13 3 2 Ou tp tiromthe FIN ig canard ster aopl reoni n a EE n Aar EE EEE ETONE S 13 Io TARAP aT GG AE 13 6 MEMS Sensor EEPROM Interface Os 14 7 RF Front End Design dawnt scttansctctanbousdddnsasaehiassidediucsatotdebseneicacdovebebvebadiand 15 TAs JRE S192 REGUIPOMICING se ee ee i 16 7 2 GPS Antenna Polarization 17 Tae GPS Antina Ca EENE OE EEE ETETE ERENS rE SOENEN ia 17 did Sy en No e OO 18 7d Ac ye versus Passive ANGINA ea 18 To RETO LCOS eoa EE E EE E EEA E 18 7 71 Implications of the Pre select SAW Filter 4 18 7 8 External LNA Gain and Noise Figure pp 19 7 9 Powering the External LNA active antenna pp 20 Ea R ADM Fa at a R 3 Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 5 of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 TAO RE mn E ee eee eee eee 21 T e a ERO ER E 21 8 Reference Design
27. ext Conventions Danger This information MUST be followed or catastrophic equipment failure or bodily injury may occur Caution or Warning Alerts the user to important points about integrating the module if these points are not followed the module and end user equipment may fail or malfunction Tip or Information Provides advice and suggestions that may be useful when integrating the module Mp R ADM Fa at a R 3 rf ation from Telit Communications S p A All Rights Reserved Page 8 of 32 e Telit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 All dates are in ISO 8601 format i e YYYY MM DD 1 6 Related Documents e JN3 Product Description e J F2 EVK User Guide 7 a 7 A fe J z E af y vA A ADM gi i gt yi i yea er 2 pe Pe f tas Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 9 of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 2 Powering the JN3 2 1 3 3V Supply Voltage The JN3 is powered by applying 3 3 volts DC to the VCC_IN pin of the module Internal regulators reduce the supply voltage to the nominal 1 8 volts DC required by the internal electronics The JN3 monitors the 3 3 volt supply and issues an internal hardware reset if the supply drops below 2 5 volts This reset protects the memory from accidental writes during
28. f tow rp p ie n l J i ae d f s gt A ak 2 of i Ld Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 20 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 7 10 RF Interference RF Interference into the GPS receiver tends to be the biggest problem when determining why the system performance is not meeting expectations As mentioned earlier the GPS signals are at 130 dBm and lower If signal higher than this are presented to the receiver it can be overwhelmed The JN3 can reject up to 8 CW in band jamming signals but would still be affected by non CW signals The most common source of interference is digital noise This is created by the fast rise and fall times and high clock speeds of modern digital circuitry For example a popular netbook computer uses an Atom processor clocked at 1 6 GHz This is only 25 MHz away from the GPS signal and depending upon temperature of the SAW filter can be within the passband of the GPS receiver Because of the nature of the address and data lines this would be broadband digital noise at a relatively high level Such devices are required to adhere to a regulatory standard for emissions such as FCC Part 15 Subpart J Class B or CISPR 22 However these regulatory emission levels are far higher than the GPS signal 7 11 Shielding Shielding the RF circuitry generally is ineffective because the interfe
29. f 32 1 4 1 5 Reproduction forbidden without written authoriz i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Document Organization Chapter 1 Introduction provides a scope for this document target audience contact and support information and text conventions Chapter 2 Powering the SL868 gives an overview about power supply Chapter 3 Updating Firmware describes the SW updating procedure for Flash version Chapter 4 Updating Patch code describes how to apply patch code to ROM version Chapter 5 Main serial interface describes the serial interface Chapter 6 MEMS sensor and EEPROM Interface describes the DR 12C interface Chapter 7 RF Front End Design describes in details the characteristics of the Front end Chapter 8 Reference Design gives an overview about the reference design Chapter 9 Firmware configuration describes the configuration settings Chapter 10 Handling and soldering describes packaging and soldering of the module Chapter 11 PCB layout details describes the mechanical design of the module Chapter 12 Safety recommendations provides some safety recommendations that must be followed by the customer In the design of the application that makes use of the SL868 Chapter 13 Document History describes the history of the present product T
30. hether patch data must be sent to the module by polling the software version which reflects the currently applied patch file version Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 12 of 32 5 1 3 2 5 3 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Main Serial Interface Upon power up the JN3 will communicate using a standard asynchronous 8 bit protocol UART with messages appearing on the TX line and commands and data being entered on the RX line There is no parity bit and no flow control operations are performed Input to the JN3 Maximum sustained inflow at the rate of command messages should not exceed about 10 000 characters per second Above 115 2kbps such as 1228800 bps 122880 characters per second input flow should be limited to less than 10 000 characters sec to keep from choking the system Command processing is a low priority task within the system At higher data rates TELIT recommends using OSP message ACK protocol to prevent message loss Low data rates impact startup and TTFF values in sending configuration commands and patches to ROM based devices and when using host storage for JN3 data files Output from the JN3 Users can control selection and rate of delivery of some output messages through OSP or NMEA configuration commands Debug messages are controlled as a block and cannot be individually selected
31. higher gain LNA 1s used either a resistive Pi or T attenuator can be inserted after the LNA to bring the gain down to 14 dB or the JN3 can be switched into a low gain mode by issuing an OSP command to do so The external LNA should have a noise figure better than 1 dB This will give an overall system noise figure of around 2 dB assuming the LNA gain is 14 dB or if higher the low gain mode is selected within the JN3 The external LNA if having no pre select filter needs to be able to handle other signals other than the GPS signal These signals are typically at much higher levels The amplifier needs to stay in the linear region when presented with these other signals Again the system designer needs to determine all of the unintended signals and their possible levels that can be presented and make sure the external LNA will not be driven into compression If this were to happen the GPS signal itself would start to be attenuated and the GPS performance would suffer Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 19 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 7 9 Powering the External LNA active antenna The external LNA needs a source of power Many of the active antennas accept a 3 volt or 5 volt DC voltage that is impressed upon the RF signal line This voltage is not supplied by the JN3 but can be easily supplied by the host design Two a
32. hort at that frequency V_ANT is the supply voltage for the external active antenna TX is the normal digital output and is a serial UART with a default bit rate of 4800 bps 1 stop bit and 8 data bits This is a 3 3 volt logic level signal As is the case with all serial data the idle state is logic one RX is the normal digital input and is a serial UART with a default bit rate of 4800 bps 1 stop bit and 8 data bits This is a 1 8 volt logic level signal but is tolerant to 3 6 volts As is the case with all serial data the idle state is logic one Note Connection to Boot signal is not required for EEPROM and ROM only modules Note Do not drive any of the GPIOs Rx line HIGH while no power is applied to the module re el biden without written authorization from Telit Communications SD A All Rights Reserved Page 22 of 32 9 1 9 2 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Firmware Configuration The JN3 can be configured by means of firmware in order to fit better into the overall system This section describes certain aspects of the receiver that can be configured Internal LNA The JN3 offers two modes of operation high gain mode and low gain mode for the internal LNA The high gain mode is the default mode and provides 16 to 20dB of gain The low gain mode provides 6 to 10dB of gain In general the high gain mode is intended for use with passive antennas while the low gain mode is used whe
33. lf blank see adjacent bar code label 3 After bag is opened devices that will be subject to reflow solder or other high temperature process must be a mounted within 48 hours at factory conditions If blank see adjacent bar code label lt 30 C 60 RH or b stored at 10 RH Devices require baking before mounting if a humidity indicator card is gt 10 when read at 23 5 C b condition 3a or 3b not met 5 If baking is required devices may be baked for 48 hours at 1252 5 C Note If device containers cannot be subjected to high temperature or shorter bake times are desired reference IPC JEDEC STD 033 for bake procedure Bag seal date C lf blank see adjacent bar code label Note Level and body temperature defined by IPC JEDEC J STD 020 Figure 2 Label for Moisture Sensitive Devices j A TE Ee Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 28 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 10 2 ESD The JN3 is an electrostatic discharge sensitive device and should be handled in accordance with JESD625 A requirements for Handling Electrostatic Discharge Sensitive ESDS Devices Although the JN3 is a module the expecting handling of the JN3 during assembly and test is identical to that of a semiconductor device Note JEDEC standards are available for free from the JEDEC website http www jedec org
34. n there is an external LNA as part of the RF front end e g active antenna The recommended external LNA gain is 20dB A version of JN3 firmware is offered for system designs that require the low LNA gain mode The gain mode is selected by the firmware when the receiver starts up The Tracker Config message OSP MID178 SID2 can also be used to change the LNA mode but note that the use of this message is not recommended because an incorrect parameter could render the JN3 inoperable Contact Telit technical support if this approach is required in your system TricklePower Low Power Mode In addition to full power mode the JN3 module can be operated in the TricklePower power management mode Full power mode consumes more average power but it is the more accurate navigation mode and supports the most dynamic motion scenarios TricklePower mode is a duty cycling mode It provides navigation updates at a fixed rate and retains a high quality of GPS accuracy and dynamic motion response but at a lower average power cost as compared to Full Power operation TricklePower mode produces significant power savings in strong signal conditions Depending upon the requirements of the system design regarding frequency of position updates and availability of GPS signals in the operational environment the designer can choose the mode that provides the better trade off of performance versus power consumption TricklePower mode can be commanded using the Powe
35. o switch the protocol to OSP as described in the next section Use the Query Rate Control PSRF103 to enable and disable output messages and set their output rates OSP Considerations The higher baud rates are used for OSP OSP offers a richer set of commands and more types of data output than does NMEA Use the Set Serial Port PSRF100 NMEA command to switch the protocol from NMEA to OSP The minimum recommended baud rate for OSP is 38400 provided that debug data messages are not enabled If data debug messages are enabled the minimum baud rate is 115200 in order to prevent data from being dropped The protocol can be switched back to NMEA using the Switch to NMEA Protocol command Message ID 129 MEMS Configuration The JN3 module interfaces to MEMS sensors using the DR I2C bus as mentioned above in Section 6 The sensors that may be connected are an accelerometer and a magnetometer also called a digital compass A Sensor Configuration OSP message Message ID 234 Sub ID 1 must be sent to the JN3 in order to configure it to interface with the connected sensor or sensors The configuration data in this message is extensive and is described in detail in the OSP Manual After the sensor interface has been configured the sensors must be enabled using the Sensor Switch message Message ID 234 Sub ID 2 Once the sensor interface has been configured and the sensors enabled the sensor data will be output by the JN3 in OSP Message 72 Sub ID
36. of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 10 Handling and soldering 10 1 Moisture Sensitivity The JN3 module has a moisture sensitivity level rating of 3 as defined by IPC JEDEC J STD 020 This rating is assigned due to some of the components used within the JN3 The JN3 is supplied in trays or tape and reel and is hermetically sealed with desiccant and humidity indicator card The JN3 parts must be placed and reflowed within 48 hours of first opening the hermetic seal provided the factory conditions are less than 30 C and less than 60 and the humidity indicator card indicates less than 10 relative humidity If the package has been opened or the humidity indicator card indicates above 10 then the parts will need to be baked prior to reflow The parts may be baked at 125 C 5 C for 48 hours However the trays nor the tape and reel can withstand that temperature Lower temperature baking is feasible if the humidity level is low and time is available Please see IPC JEDEC J STD 033 for additional information Additional information can be found on the MSL tag affixed to the outside of the hermetical seal bag Note JEDEC standards are available for free from the JEDEC website http www jedec org CAUTION This bag contains MOISTURE SENSITIVE DEVICES Calculated shelf life in sealed bag 12 months at lt 40 C and 90 relative hunidity RH 2 Peak package body temperature 240 C
37. om Telit Communications S p A All Rights Reserved Page 18 of 32 7 8 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 LNA Filter devices pass the desired in band signal to the output resulting in low reflected energy good return loss and reject the out of band signal by reflecting it back to the input resulting in high reflected energy bad return loss If an external amplifier is to be used with the JN3 the overall design should be checked for RF stability to prevent the external amplifier from oscillating Amplifiers that are unconditionally stable at the output will be fine to use with the JN3 If an external filter is to be connected directly to the JN3 care needs to be used in making sure neither the external filter nor the internal SAW filter performance is compromised These components are typically specified to operate into 50 ohms impedance which is generally true in band but would not be true out of band If there is extra gain associated with the external filter then a 6 dB Pi or T resistive attenuator is suggested to improve the impedance match between the two components External LNA Gain and Noise Figure The JN3 can be used with an external LNA such as what might be found in an active antenna Because of the internal LNA the overall gain including signal losses past the external LNA should not exceed 14 dB Levels higher than that can affect the jamming detection capability of the JN3 If a
38. pproaches can be used The first is to use an inductor to tie directly to the RF trace This inductor should be at self resonance at L1 1 57542 GHz and should have good Q for low loss the higher the Q the lower the loss The side of the inductor connecting to the antenna supply voltage should be bypassed to ground with a good quality RF capacitor again operating at self resonance at the L1 frequency The second approach is to use a quarter wave stub in place of the inductor The length of the stub is designed to be exactly a quarter wavelength which has the effect of making an RF short at L1 at one end of the stub to appear as an RF open The RF short is created by the good quality RF capacitor operating at self resonance The choice between the two would be determined by e RF path loss introduced by either the inductor or quarter wave stub e Cost of the inductor e Space availability for the quarter wave stub Simulations done by Telit show the following e Murata LQG15HS27NJ02 Inductor 0 65 dB of additional signal loss e Quarter wave stub on FR4 0 59 dB of additional signal loss e Coilcraft BOOTJLC Inductor used in ref design 0 37 dB of additional signal loss This additional loss occurs after the LNA in the active antenna so it is generally not significant unless the circuit is being designed to work with either an active or a passive antenna 7 a lt PE 5 lt P re 5 a gt A S S _ k FA
39. r Mode Request Message MID218 which is available as part of the OSP message set This message can also be used to command the receiver back to Full Power mode More details regarding low power operation can be found in the Low Power Operating Modes Application Note Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 23 of 32 9 3 9 3 1 9 3 2 9 4 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Host Serial Interface As mentioned above in Section 5 the host serial interface is a UART The UART can operate at baud rates of 4800 9600 19200 38400 57600 115200 230400 and 460800 bps NMEA Protocol Considerations The lower UART baud rates are typically used for NMEA protocol Note should be taken however of the bandwidth limitation at 4800 baud By default the JN3 module communicates using NMEA at 4800 baud with the periodic output messages limited to the GGA GSA and RMC messages at once per second and the GSV message once every five seconds At 9600 baud or higher additional output messages may be enabled If the JN3 is operated in TricklePower mode a baud rate of at least 38400 is recommended This reduces the time required for data output and allows the receiver to drop into the lowest power state for a longer average time Use the Set Serial Port PSRF100 NMEA command to change the baud rate This command can also be used t
40. references to or information about Telit products machines and programs programming or services that are not announced in your country Such references or information must not be construed to mean that Telit intends to announce such Telit products programming or services in your country Copyrights This instruction manual and the Telit products described in this instruction manual may be include or describe copyrighted Telit material such as computer programs stored in semiconductor memories or other media Laws in the Italy and other countries preserve for Telit and its licensors certain exclusive rights for copyrighted material including the exclusive right to copy reproduce in any form distribute and make derivative works of the copyrighted material Accordingly any copyrighted material of Telit and its licensors contained herein or in the Telit products described in this instruction manual may not be copied reproduced distributed merged or modified in any manner without the express written permission of Telit Furthermore the purchase of Telit products shall not be deemed to grant either directly or by implication estoppel or otherwise any license under the copyrights patents or patent applications of Telit as arises by operation of law in the sale of a product Computer Software Copyrights The Telit and 3rd Party supplied Software SW products described in this instruction manual may include copyrighted Telit and other 3rd
41. rence is getting into the GPS antenna itself the most sensitive portion of the RF path The antenna cannot be shielded because then it can t receive the GPS signals There are two solutions one is to move the antenna away from the source of interference or the second is to shield the digital interference to prevent it from getting to the antenna gt d ai s te F F srg A Sy FS i 7 pi i OES i h g 23 oy a A gt a Kit ar RY ie he WI fc is gt a amp a ts ERER Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 21 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 8 Reference Design The JN3 Reference Design is presented in the figure below CC VCC IN 4 _ RX gt X VANT Figure 1 JN3 Reference Design Along with power and ground the minimum number of signals required to operate the JN3 properly are two digital signals and one RF signal The RF input can be connected directly to a GPS antenna The reference design shows a DC power feed for an active antenna C5 is used to block the DC voltage from entering the JN3 The inductor L1 is chosen to be self resonant at the GPS frequency 1 57542 GHz to minimize loading on the RF trace Capacitor C6 is chosen to be self resonant at the GPS frequency such that is looks pretty close to an RF s
42. s because electrostatic discharges may damage the product itself Same cautions have to be taken for the SIM checking carefully the instruction for its use Do not insert or remove the SIM when the product is in power saving mode The system integrator is responsible of the functioning of the final product therefore care has to be taken to the external components of the module as well as of any project or installation issue because the risk of disturbing the GSM network or external devices or having impact on the security Should there be any doubt please refer to the technical documentation and the regulations in force Every module has to be equipped with a proper antenna with specific characteristics The antenna has to be installed with care in order to avoid any interference with other electronic devices and has to guarantee a minimum distance from the body 20 cm In case of this requirement cannot be satisfied the system integrator has to assess the final product against the SAR regulation The European Community provides some Directives for the electronic equipments introduced on the market All the relevant information s are available on the European Community website http ec europa eu enterprise sectors rtte documents The text of the Directive 99 05 regarding telecommunication equipments is available while the applicable Directives Low Voltage and EMC are available at http ec europa eu enterprise sectors electrical
43. satellites to transmit regional differential corrections via a GPS compatible signal The use of SBAS corrections can improve typical position accuracy to 3m or less in open sky applications Note that only an SBAS can be used as source of differential corrections Other sources such as data from RTCM beacons are not supported By default the JN3 does not attempt to acquire SBAS satellites This can be changed by sending in a DGPS Source command MID 133 and specifying the source of DGPS corrections as SBAS When the receiver acquires SBAS satellites it will demodulate and use corrections data from the satellite signal The receiver can be configured to compute SBAS satellite range measurements and use them in the navigation solution This can be enabled through a control bit in the OSP Mode Control command MID 136 See the OSP Manual for details 2 D Acquisition By default the JN3 will compute a 2 D solution when possible when performing initial acquisition In a 2 D solution the receiver assumes a value for altitude and uses it to estimate P Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 26 of 32 i el it JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 the horizontal position Under warm and hot start conditions the receiver uses the last known value of altitude which is a good assumption in most situations However under cold start conditions the las
44. sh memory However 1f the internal flash memory needs to be updated the following steps should be performed to place the JN3 module into a state suitable for programming the internal flash memory 1 Remove all power to the module 2 Pull the BOOT signal high through a 10K pull up resistor to 1 8 volts Note The BOOT signal is not 3 3 volt tolerant 3 Apply main power 4 Run the software utility to re flash the JN3 module Clearing the entire flash memory is strongly recommended prior to programming 5 Upon successful completion of re flashing remove main power to the module for a minimum of 10 seconds 6 Pull the BOOT signal low through a 100K pull down resistor to GND 7 Apply main power to the JN3 8 Verify the JN3 has returned to the normal operating state p x es 2 y f P m gs f uit Ao Bs pares re yes A p gt i a ai lt xe f 2 pr Dre H ss AN ZA Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 11 of 32 i lit JN3 Hardware User Guide 1vv0300984 Rev 2 2012 08 06 Updating Patch Code EEPROM and ROM modules with Host Memory Modules with EEPROM and ROM only designs using external Host memory support firmware patching Firmware patches for the EEPROM module are stored inside the I2C serial EEPROM device Firmware patches for the ROM only module are stored externally using Host memory At power up pat
45. t position is unknown and the receiver assumes a value of 0 In situations where the true altitude is significantly higher than that the horizontal position estimate will be noticeably impacted To accommodate applications for which these situations are a concern a version of JN3 firmware is offered that requires a calculated altitude 1 e a 3 D navigational solution in order for the receiver to first enter navigation 9 6 4 MEMS Compass Heading The JN3 module incorporates a feature that reads and reports the compass heading from a 3 axis magnetometer The raw heading data is used to enhance navigation performance under low speed conditions The raw heading data is also reported over the OSP message interface The compass heading information meets the following general performance guidelines e 50 Heading Accuracy 2 Deg e 95 Heading Accuracy 5 Deg NOTE The magnetic compass feature and performance is affected by the magnetic environment due to magnetic anomalies These can typically be caused by large masses of ferrous metal such as iron as well as natural disturbances in the earth s magnetic field These magnetic anomalies cause errors in the sensing of the magnetic field and result in larger than specified errors P 2 4 5 a lt F n fe J y n i gt p y f iv A Ade Di 4 4 et lt wag Fa Reproduction forbidden without written authorization from Telit Communications S p A All Rights Reserved Page 27
46. ure an acceleration threshold is programmed into the actual sensor device If the programmed threshold is exceeded the interrupt output from the accelerometer device becomes active If MPM is in a degraded mode lack of signal acquisition during the periodic update cycles and the software is configured to allow sensor wakes the MEMS Wake up will attempt more frequent calibration cycles under the assumption that movement of the receiver may result in different and or better signal conditions Advanced Features CW Jamming Detection The JN3 module detects tracks and removes narrow band interfering signals jammers without the need for external components or tuning It monitors a frequency band that is 4MHz from the L1 frequency for jammers Any number of jammers that occur outside of a 1 MHz center band are removed by the JN3 with a 2MHz band pass filter Up to eight jammers inside this center band are removed using a notch filter Data regarding detected jammers is output using OSP messages Message ID 92 Sub ID 1 reports up to eight of the most recently detected interferers This feature is useful both in the design stage and during the production stage for uncovering issues related to unexpected jamming SBAS The JN3 receiver is capable of using Satellite Based Augmentation System SBAS satellites as a source of both differential corrections and satellite range measurements These systems WAAS EGNOS MSAS use geostationary
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