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                SL871 Family Product User Guide 

 

 
1VV0301170 Rev. 9  

Page 55 of 89 

2021-07-15 

Not Subject to NDA 

 Each GNSS satellite presents its own signal to the  receiver, and best performance is 
obtained when the signal levels are between -130 dBm and -125 dBm. These received 
signal levels are determined by: 

•

 

Satellite transmit power 

•

 

Satellite elevation angle 

•

 

Free space path loss 

•

 

Extraneous path loss (such as rain) 

•

 

Partial or total path blockage (such as foliage or buildings) 

•

 

Multipath interference (caused by signal reflection) 

•

 

GNSS antenna characteristics 

•

 

Signal path after the GNSS antenna 

The GNSS signal is relatively immune to attenuation from rainfall. However, it is heavily 
influenced by attenuation due to foliage (such as tree canopies, etc.) as well as outright 
blockage  caused  by  buildings,  terrain  or  other  objects  near  the  line  of  sight  to  each 
specific  GNSS  satellite.  This  variable  attenuation  is  highly  dependent  upon  satellite 
location. If enough satellites are blocked, say at a lower elevation, or all in one general 
direction, the geometry of the remaining satellites will be worse (higher DOP) and will 
result in a lower position accuracy. The receiver reports this geometry effect in the form 
of PDOP, HDOP and VDOP numbers. 

For  example,  in  a  vehicular  application,  the  GNSS  antenna  may  be  placed  on  the 
dashboard or rear package tray of an automobile. The metal roof of the vehicle will cause 
significant blockage, plus any thermal coating applied to the vehicle glass can attenuate 
the  GNSS  signal  by  as  much  as  15  dB.  Again,  both  of  these  factors  will  affect  the 
performance of the receiver. 

Multipath  interference  results  when  the  signal  from  a  particular  satellite  is  reflected 
from a surface (e.g. a building or the roof of a car) and is received by the GNSS antenna 
either in addition to or in place of the line of sight signal. The reflected signal has a path 
length  that  is  longer  than  the  line  of  sight  path  and  can  either  attenuate  the  original 
signal,  or,  if  received  in  place  of  the  original  signal,  can  add  error  in  determining  a 
solution  because  the  distance  to  the  particular  satellite  is  actually  shorter  than 
measured.  It  is  this  phenomenon  (as  well  as  the  partial  sky  obscuration)  that  makes 
GNSS navigation in urban canyons (narrow roads surrounded by high rise buildings) so 
challenging. In general, the reflection of a GNSS signal causes its polarization to reverse. 
The implications of this are covered in the next section. 

Содержание SL871

Страница 1: ...SL871 Family Product User Guide 1VV0301170 Rev 9 2021 07 15 Telit Technical Documentation...

Страница 2: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 2 of 89 2021 07 15 Not Subject to NDA APPLICABILITY TABLE PRODUCTS SL871 SL871L SL871 S SL871L S...

Страница 3: ...PTION 10 Product Overview 10 Product Naming 11 Product Variants 11 SL871 S and SL871L S Features 11 2 3 1 1 ROM versions 12 SL871 Product Features Table 12 Block Diagrams 13 SL871 Gen 2 Block Diagram...

Страница 4: ...I O Ports 23 Power Management Modes 23 Full Power Continuous Mode 24 Backup Mode Perpetual SL871 and SL871L only 24 Standby Modes 25 GLP Mode SL871 and SL871L modules only 25 Periodic Modes SL871 and...

Страница 5: ...y 42 VCC 42 VBATT 42 VCC_RF 43 DC Power Requirements 43 DC Power Consumption SL871 Gen 2 43 DC Power Consumption SL871L 44 DC Power Consumption SL871 S 44 DC Power Consumption SL871L S 45 Digital Inte...

Страница 6: ...nterference Cancellation 53 10 RF FRONT END DESIGN 54 RF Signal Requirements 54 GNSS Antenna Polarization 56 Active versus Passive Antenna 56 GNSS Antenna Gain 56 System Noise Floor 57 RF Trace Losses...

Страница 7: ...clarations of Conformity 75 EU RED Declaration of Conformity SL871 75 EU RED Declaration of Conformity SL871L 76 EU RED Declaration of Conformity SL871 S 77 EU RED Declaration of Conformity SL871L S 7...

Страница 8: ...pplications using the Telit SL871 family Contact Information Support For general contact technical support services technical questions and report of documentation errors contact Telit Technical Suppo...

Страница 9: ...advice and suggestions that may be useful when integrating the module Electro static Discharge Notifies the user to take proper grounding precautions before handling the product Table 1 Symbol Convent...

Страница 10: ...1L S modules also include a built in LNA and DC blocking cap Constellations o SL871x GPS L1 QZSS and either Glonass L1 or BeiDou B1 simultaneous ranging with 99 search and 33 tracking channels Galileo...

Страница 11: ...1 See Table 2 SL871 Family Product Features for EASY and EPO support Product Naming SL871 Product family name S GPS only ROM based receiver L Added LNA and DC blocking capacitor Product Variants The S...

Страница 12: ...1L S Please refer to the MT333x Host EPO Application Note 2 3 1 1 ROM versions The current SL871 S and SL871L S have the MT3337E enhanced ROM with the following changes Added features Improved TTFF an...

Страница 13: ...L871L S Force On Yes No Software Upgradable Yes No EPO Yes Yes host Table 2 SL871 Family Product Features Feature SL871 S Early production SL871L S ROM version 3337 3337E enhanced EASY No Yes SBAS Yes...

Страница 14: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 14 of 89 2021 07 15 Not Subject to NDA SL871L Block Diagram Figure 2 SL871L Block Diagram SL871 S Block Diagram Figure 3 SL871 S Block Diagram...

Страница 15: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 15 of 89 2021 07 15 Not Subject to NDA SL871L S Block Diagram Figure 4 SL871L S Block Diagram...

Страница 16: ...Family Product User Guide 1VV0301170 Rev 9 Page 16 of 89 2021 07 15 Not Subject to NDA Module Photo Figure 5 SL871 Family Module Photo Note All variants have similar appearance except for the product...

Страница 17: ...170 Rev 9 Page 17 of 89 2021 07 15 Not Subject to NDA 3 EVALUATION KIT Please refer to the product Evaluation Kit User Guide for detailed information Figure 6 Evaluation Kit Contents Note The SL871 ki...

Страница 18: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 18 of 89 2021 07 15 Not Subject to NDA Evaluation Unit Figure 7 SL871 Evaluation Unit...

Страница 19: ...m QZSS constellation usage is controlled by the PMTK352 command and is disabled by default NMEA reporting for QZSS may be enabled disabled by the PMTK351 command Satellite Based Augmentation System SB...

Страница 20: ...ssisted GPS or Aided GPS is a method by which information from a source other than broadcast GPS signals is used to improve i e reduce TTFF The necessary ephemeris data is calculated either by the rec...

Страница 21: ...use of Assisted GPS If the system design includes a host processor it can access server generated EPO data and send it to the module over a serial port This data is valid for six hours Host EPO data i...

Страница 22: ...receiver module detects and removes narrow band interfering signals jamming signals without the need for external components or tuning It rejects up to 12 CW Continuous Wave type signals of up to 80 d...

Страница 23: ...T3337 based modules is UART and cannot be changed Please refer to section 9 4 Serial I O Ports for details Power Management Modes The receiver supports operating modes that reduce overall current cons...

Страница 24: ...p This mode uses the acquisition engine to search for all possible satellites at full performance resulting in the highest sensitivity and the shortest possible TTFF The receiver then switches to the...

Страница 25: ...and RF and TCXO are powered down SLEEP ARM baseband and RF are powered down To enter a Standby mode send the following command PMTK161 0 28 STOP Mode PMTK161 1 29 SLEEP Mode To exit a Standby mode sen...

Страница 26: ...d LS871L only These modes allow autonomous power on off control with reduced fix rate to decrease average power consumption The main power supply pin VCC_ON is still powered but power distribution to...

Страница 27: ...the limit between successive DEE PMTK225 Type Run_time Sleep_time 2nd_run_time 2nd_sleep_time che ckum Where Type 1 for Periodic backup mode or 2 for Periodic standby mode Run_time Full Power period m...

Страница 28: ...ly Depending on the environment and motion conditions the module can autonomously and adaptively adjust the parameters of the Periodic mode e g RF on off ratio and fix rate to achieve a balance in pos...

Страница 29: ...ata use the PMTK127 command Data Retention 1 Initialization Almanac Ephemeris EPO Host EPO EASY Position Time Power Cycle Y 2 Reset signal Y Full Cold Start Y 3 Cold Start Y Y Y Y 3 Warm Start Y Y Y Y...

Страница 30: ...y Constellation s CEP m GPS 2 5 Glonass 2 6 BeiDou 10 2 GPS Glonass 2 5 GPS BeiDou 2 5 Test Conditions 24 hr Static 130 dBm Full Power mode Table 6 SL871 and SL871L Horizontal Position Accuracy Time t...

Страница 31: ...n 160 163 Tracking 162 165 GLONASS Acquisition 144 146 Navigation 156 159 Tracking 158 161 BeiDou Acquisition 143 146 Navigation 156 159 Tracking 158 162 Note The above performance values were measure...

Страница 32: ...ions 130 dBm Full Power mode Static scenario Table 10 SL871 S and SL871L S Time to First Fix Sensitivity SL871 S and SL871L S Constellation State Minimum Signal Level dBm SL871 S Gen 2 SL871L S GPS Ac...

Страница 33: ...L871 Family Product User Guide 1VV0301170 Rev 9 Page 33 of 89 2021 07 15 Not Subject to NDA Jamming Mitigation Performance Example Figure 13 Jamming with AIC Disabled Figure 14 Jamming with AIC Enable...

Страница 34: ...ement NDA with Telit may obtain the Telit MT GNSS Authorized Software User Guide which contains additional proprietary information NMEA Output Messages Warning Some sentences may exceed the NMEA lengt...

Страница 35: ...eport additional receiver data and status information Message ID Description PMTK010 System messages e g to report startup etc Table 15 Proprietary Output Messages NMEA Input Commands The modules use...

Страница 36: ...time is preserved PMTK104 Perform a system reset erasing any stored almanac data and then a COLD start PMTK120 Erase aiding data stored in flash memory PMTK127 Erase EPO data stored in flash memory P...

Страница 37: ...ed via the serial port TX RX pins In order to update the FW the following steps should be performed to re program the module 1 Remove all power to the module 2 Connect serial port USB cable to a PC 3...

Страница 38: ...User Guide 1VV0301170 Rev 9 Page 38 of 89 2021 07 15 Not Subject to NDA 9 ELECTRICAL INTERFACE Pinout Diagrams and Tables SL871 Gen 2 and SL871L Pin out Diagram and Table Figure 15 SL871 Gen 2 and SL...

Страница 39: ...ee 9 3 3 1 RESET N 10 GND GND Ground 11 RF IN I GNSS RF Input 50 See 9 5 Antenna RF Interface Max DC voltage 3 0 V Gen 2 1 12 GND GND Ground 13 ANT ON O Antenna On See 9 3 2 2 ANT ON output 14 VCC RF...

Страница 40: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 40 of 89 2021 07 15 Not Subject to NDA SL871 S and SL871L S Pin out Diagram and Table Figure 16 SL871 S and SL871L S Pin out Diagram...

Страница 41: ...er Supply 9 RESET N I RESET N Active Low open drain May be left unconnected See 9 3 3 1 RESET N 10 GND GND Ground 11 RF IN I GNSS RF Input 50 See 9 5 Antenna RF Interface Max DC voltage 3 0 V Gen 2 1...

Страница 42: ...s The supply must be able to handle the current fluctuation including any inrush surge current GPS GNSS receiver modules require a clean and stable power supply In designing such a supply any resistan...

Страница 43: ...up Voltage Supply Name Min Typ Max Units Vcc and Vbatt Vcc Vbatt 2 8 3 3 4 3 V The drop from 2 7 V to 0 V must be 1 ms Also keep the supply ripple as low as possible 50 mV Table 19 DC Supply Voltage D...

Страница 44: ...w Power Periodic 500 ms duty cycle GPS Only 37 mW GPS Glonass 41 mW GPS BeiDou 40 mW Low Power AlwaysLocate Standby GPS Only 27 mW GPS Glonass 34 mW GPS BeiDou 33 mW Vbatt 50 99 W Operating temperatur...

Страница 45: ...te that I O voltage ranges are different from supply voltages VCC and VBATT Warning Several different logic levels are utilized by the digital signal interfaces of the module as shown in the tables be...

Страница 46: ...ol 2 mA Output Current H Ioh 2 mA Table 26 Output Logic Levels TX and 1PPS ANT ON Signal Symbol Min Typ Max Units Output Voltage L Vol 0 4 V Output Voltage H Voh 2 71 2 89 V Normal Current L Iol 2 mA...

Страница 47: ...is only available on the SL871 and SL871L The logic levels are shown in Table 24 Input Logic Levels RX and Reset N Ant Sense Note that this pin can be configured to be Data Ready Indicator for I2C 9...

Страница 48: ...received the module will enter the Standby stop state rather than the Backup state since the PMU is still on This signal is only available on the SL871 Gen 2 and SL871L Warning Note that this pin has...

Страница 49: ...port is UART interface on all modules The secondary port TX1 SDA and RX1 SCL interface depends on the module SL871 SL871L The secondary port is I2 C It can be changed to UART via PMTK258 command Note...

Страница 50: ...s are LVTTL compatible See section 9 3 1 I O Signal Levels UART TX logic levels are shown in Table 26 Output Logic Levels TX and 1PPS UART RX logic levels are shown in Table 24 Input Logic Levels RX a...

Страница 51: ...tart The buffer will contain up to 254 data bytes plus an LF x 0A character Each NMEA sentence will be terminated by the standard CR LF x 0D x 0A characters and a NMEA sentence can span buffers If nec...

Страница 52: ...them to work well with a passive GNSS antenna For improved performance or if the antenna cannot be located near the receiver an active antenna that is an antenna with a built in low noise amplifier c...

Страница 53: ...t is effective against narrow band clock harmonics Jamming Rejection is not effective against wide band noise e g from a host CPU memory bus or switching power supply because these sources typically c...

Страница 54: ...e or ephemeris aiding is available acquisition can be accomplished at lower signal levels The GPS signal is defined by Interface Specification IS GPS 200 This document states that the signal level rec...

Страница 55: ...er position accuracy The receiver reports this geometry effect in the form of PDOP HDOP and VDOP numbers For example in a vehicular application the GNSS antenna may be placed on the dashboard or rear...

Страница 56: ...l may be better than no signal The system designer needs to understand trade offs in their application to determine the better choice Active versus Passive Antenna If the GNSS antenna is placed near t...

Страница 57: ...tenna Y by about 10 dB An antenna with higher gain will generally outperform an antenna with lower gain However once the signals are above about 130 dBm for a particular satellite no improvement in pe...

Страница 58: ...t to maintain a 50 impedance on the RF path trace Design software for calculating trace impedance can be found from multiple sources on the internet The best method is to contact your PCB supplier and...

Страница 59: ...romised 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...

Страница 60: ...wave stub Simulations done by Telit show the following results Inductor Additional signal loss dB Murata LQG15HS27NJ02 Inductor 0 65 Quarter wave stub on FR4 0 59 Coilcraft B09TJLC Inductor used in r...

Страница 61: ...or CISPR 22 However these regulatory emission levels are far higher than the GNSS signal strength Shielding Shielding the RF circuitry generally is ineffective because the interference is received by...

Страница 62: ...dule but is not required on SL871L modules since they include an internal DC blocking capacitor Inductor L1 is chosen to be self resonant at the GNSS frequency approximately 1 57542 GHz to minimize lo...

Страница 63: ...r Guide 1VV0301170 Rev 9 Page 63 of 89 2021 07 15 Not Subject to NDA Refer to the tables in chapter 9 Electrical Interface for logic levels Note that some pins are different for the SL871 S See chapte...

Страница 64: ...to NDA 12 MECHANICAL DRAWING The SL871 modules use advanced miniature packaging with a base metal of copper and an Electroless Nickel Immersion Gold ENIG finish There are 18 interface pads with castel...

Страница 65: ...Subject to NDA 13 PCB FOOTPRINT The PCB footprint on the PC board should match the module pad design shown below The solder mask opening is generally determined by the component geometry of other par...

Страница 66: ...ntifying the product SL871 SL871L SL871 S or SL871L S and its serial number Contact a Telit representative for information on specific module serial numbers The label format is as follows Figure 21 Pr...

Страница 67: ...l form on 24 mm reels with 1000 units per reel and mini reels with 250 units per reel Each reel is dry packaged and vacuum sealed in a Moisture Barrier Bag MBB with two silica gel packs and a humidity...

Страница 68: ...thin 168 hours of first opening the hermetic seal provided the factory ambient conditions are 30 C and 60 R H and the humidity indicator card indicates less than 10 relative humidity If the package ha...

Страница 69: ...vity Note The modules contain class 1 devices and are Electro Static Discharge Sensitive ESDS Telit recommends two basic techniques for protecting ESD devices from damage Handle sensitive components o...

Страница 70: ...odule can be washed with de ionized water using standard PCB cleaning procedures The shield does not provide a water seal to the internal components of the module so it is important that the module be...

Страница 71: ...becoming dislodged if the solder reaches liquidus temperature while the module is inverted Note JEDEC standards are available free from the JEDEC website https www jedec org The recommended reflow pro...

Страница 72: ...tion about recycling this product please contact your local waste management authority or the reseller from whom you purchased the product Safety Danger Improper handling and use of this module can ca...

Страница 73: ...maximum Humidity Up to 95 non condensing or a wet bulb temperature of 35 C whichever is less Maximum Vehicle Dynamics 2G acceleration Table 31 Operating Environmental Limits Storage Environmental Limi...

Страница 74: ...odules comply with the following Directive 2011 65 EU art 16 on the restriction of the use of certain hazardous substances in electrical and electronic equipment RoHS Manufactured in an ISO 9001 2008...

Страница 75: ...amily Product User Guide 1VV0301170 Rev 9 Page 75 of 89 2021 07 15 Not Subject to NDA EU RED Declarations of Conformity EU RED Declaration of Conformity SL871 Figure 26 EU RED Declaration of Conformit...

Страница 76: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 76 of 89 2021 07 15 Not Subject to NDA EU RED Declaration of Conformity SL871L Figure 27 EU RED Declaration of Conformity SL871L...

Страница 77: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 77 of 89 2021 07 15 Not Subject to NDA EU RED Declaration of Conformity SL871 S Figure 28 EU RED Declaration of Conformity SL871 S...

Страница 78: ...SL871 Family Product User Guide 1VV0301170 Rev 9 Page 78 of 89 2021 07 15 Not Subject to NDA EU RED Declaration of Conformity SL871L S Figure 29 EU RED Declaration of Conformity SL871L S...

Страница 79: ...do not necessarily mean that Telit intends to announce such Telit products programming or services in your country Copyrights This instruction manual and the Telit products described herein may includ...

Страница 80: ...this document is owned by Telit and its licensors It is furnished by express license agreement only and shall be used exclusively in accordance with the terms of such agreement Copyrighted Materials...

Страница 81: ...A PARTICULAR PURPOSE NO THIRD PARTY LICENSORS OF OTHER CODES MUST BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING WITHOUT LIMITATION LOST OF PROFITS...

Страница 82: ...truction for its use Do not insert or remove the SIM when the product is in power saving mode The system integrator is responsible for the functioning of the final product Therefore the external compo...

Страница 83: ...ypically when it is powered up or restarted after a period on inactivity Almanac information may be used to identify previously visible satellites and their approximate positions Please refer to Resta...

Страница 84: ...ent a restart command Please refer to Restart LCC Leadless Chip Carrier A module design without pins In place of the pins are pads of bare gold plated copper that are soldered to the printed circuit b...

Страница 85: ...ugmentation System A system that uses a network of ground stations and geostationary satellites to provide differential corrections to GNSS receivers These corrections are transmitted on the same freq...

Страница 86: ...North American SBAS system developed by the US FAA Federal Aviation Administration Warm Start A warm start occurs when a receiver begins operation with known at least approximately time and position...

Страница 87: ...ded diagrams EASY Jamming GLP Periodic Always Loc Added power management command summary table Added configuration command references Added 1PPS information Rearranged Serial Port information Changed...

Страница 88: ...1 Correct EASY to off by default 4 6 Add note for RTCM 4 8 Add low power state Table 8 1 Correct text in Footnote 1 4 13 5 Add BACKUP mode description 8 2 2 Correct description of VBATT pin 8 4 1 9 C...

Страница 89: ......

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