Garmin GPS 25 LP, Technical Specification

Page 1: ... GPS SENSOR BOARDS GPS25 LVC GPS25 LVS GPS25 HVS TECHNICAL SPECIFICATION _______________________________________________________________________ GARMIN 1200 E 151st St Olathe Kansas 66062 913 397 8200 913 397 8282 FAX ...

Page 2: ... mechanical including photocopying and recording for any purpose without the express written permission of GARMIN Information in this document is subject to change without notice GARMIN reserves the right to change or improve their products and to make changes in the content without obligation to notify any person or organization of such changes or improvements 190 00125 00 Rev G ...

Page 3: ...hanical Dimensions 10 3 2 Connector Specifications 10 3 3 Connector Pin Out 11 3 4 Antenna Connection 14 Section 4 16 Software Interface 16 4 1 NMEA Received sentences 16 4 1 1 Almanac Information ALM 16 4 1 2 Sensor Initialization Information PGRMI 17 4 1 3 Sensor Configuration Information PGRMC 17 4 1 4 Additional Sensor Configuration Information PGRMC1 18 4 1 5 Output Sentence Enable Disable PG...

Page 4: ...ror Information PGRME 25 4 2 12 GPS Fix Data Sentence PGRMF 25 4 2 13 Sensor Status Information PGRMT 26 4 2 14 3D velocity Information PGRMV 26 4 2 15 DGPS Beacon Information PGRMB 27 4 3 Baud Rate Selection 27 4 4 One Pulse Per Second Output 27 4 5 RTCM Received Data 28 Appendix A 29 Earth Datums 29 Appendix B 32 GPS 25LP Connectors 32 Appendix C 33 GPS 25LP Evaluation Kits 33 Appendix D 35 Phas...

Page 5: ...thstand rugged operating conditions however it should be mounted in an enclosure as part of a larger system designed by an OEM or system integrator A minimum system must provide the sensor board with conditioned input power and L1 GPS RF signal The system may communicate with the board set via a choice of two CMOS TTL or two RS 232 compatible bi directional communications channels A highly accurat...

Page 6: ... features that make it easy to integrate and use 1 Full navigation accuracy provided by Standard Positioning Service SPS 2 Compact design ideal for applications with minimal space 3 High performance receiver tracks up to 12 satellites while providing fast first fix and low power consumption 4 Differential capability utilizes real time RTCM corrections producing less than 5 meter position accuracy ...

Page 7: ...ielding 2 Weight 1 3 ounce 38g 3 Size 1 83 w x 2 75 l x 0 45 h 1 4 2 Environmental Characteristics 1 Operating temperature 30 C to 85 C board temperature 2 Storage temperature 40 C to 90 C 1 4 3 Electrical Characteristics 1 Input voltage 3 6VDC to 6 0VDC regulated 150 mVp p ripple LVx versions 6 0VDC to 40VDC unregulated HVx version 2 Input current 120 mA typical 140 mA max LVx versions 20 mA whil...

Page 8: ...nd accuracy 1 microsecond at rising edge of PPS pulse subject to Selective Availability 1 4 5 Interfaces 1 Dual channel CMOS TTL level xVC versions or RS 232 compatible level xVS versions with user selectable baud rate 300 600 1200 2400 4800 9600 19200 2 NMEA 0183 Version 2 0 ASCII output GPALM GPGGA GPGSA GPGSV GPRMC GPVTG PGRME PGRMT PGRMV PGRMF LCGLL LCVTG Inputs Initial position date and time ...

Page 9: ...1 The GPS 25LP sensor boards contain a sensitive receiver Additional electromagnetic shielding may be required to prevent undesirable interference from other nearby circuits 2 The GPS 25LP sensor boards use approximately 0 5 W to 85 W depending on supply voltage and require minimal cooling Forced air cooling is not ...

Page 10: ...in the RF signal can increase acquisition time Antenna location with clear line of sight to all directions in the sky will yield the best performance 4 The GPGSV sentence contains signal strength information for the visible satellites Typical values will be between 30 db and 50 db A majority of values near the lower limit may indicate a marginal RF signal ...

Page 11: ...tellite acquisition and tracking The acquisition process is fully automatic and under normal circumstances will take approximately 45 seconds to achieve a position fix 15 seconds if ephemeris data is known After a position fix has been calculated valid position velocity and time information will be transmitted over the output channel s Like all GPS receivers the GPS 25LP utilizes initial data such...

Page 12: ...ion 4 for information altitude initialization The GPS 25LP will default to automatic differential mode looking for real time differential corrections in RTCM SC 104 standard format using message types 1 2 3 or 9 and attempting to apply them to the satellite data in order to produce a differential DGPS solution The host system at its option may also command the board set to choose differential only...

Page 13: ...ibed above The system designer should be aware of the availability of standby power input to the board set to prevent this situation 3 If the initial data is significantly inaccurate the board set will perform an operation known as AutoLocateTM This procedure is fully automatic and under normal circumstances will require 1 5 minutes to calculate a navigation solution AutoLocateTM unlike search the...

Page 14: ...s The GPS 25LP sensor board mounts via four 4 or M 3 size screws see drawing 3 2 Connector Specifications The GPS 25LP sensor boards features a single row right angle 12 pin male connector The mating connector is available from JST Corporation see appendix B ...

Page 15: ...nd fall times are 300 nSec Impedance is 250 ohms Open circuit output voltage is 0V and Vin The default format is a 100 millisecond high pulse at a 1Hz rate the pulse width is programmable from a configuration command in 20msec increments Rising edge is synchronized to the start of each GPS second This output will provide a nominal 700 mVp p signal into a 50 Ohm load The pulse time measured at the ...

Page 16: ... Pin 9 Vin Connected to Pin 10 VER 11 and above Pin 10 Vin Regulated 3 6V to 6V 200 mA maximum in the LVx versions Typical operating current is 120 mA plus antenna power Transients and overvoltages are protected by an internal 6 8V transient zener diode and a positive temperature coefficient thermistor With voltages greater than 6 8Vdc the thermistor will power the unit off until proper supply vol...

Page 17: ...irectly to the host system microprocessor through standard CMOS logic the following connections are suggested Typical Personal Computer Application Interconnect The following connections are suggestions for applications where the sensor board will be connected to a personal computer via a standard RS 232 interface ...

Page 18: ...oards provided no more than 2dB or 3dB cable loss is inserted between the antenna and the sensor Higher gain competitors antennas may be used provided there is adequate cable attenuation to prevent overloading the sensitive GPS 25LP receiver 15dB excessive antenna system gain LNA Gain Cable Loss should be considered a maximum Check to insure that the antenna in question will operate properly with ...

Page 19: ...15 Type Typical Attenuation dB 100 1 GHz RG 211A 228A 4 5 RG 217 224 293 14 5 8 RG 8 215 216 9 RG 6 11 RG 59 11 5 RG 58 20 RG 188 30 RG 174 31 RG 178 45 ...

Page 20: ...t of each sentence transmitted and received by the GPS 25LP sensor board The baud rate selection one pulse per second output interfaces and RTCM differential GPS input are also described 4 1 NMEA Received sentences The subsequent paragraphs define the sentences which can be received on RXD1 by the GPS 25LP sensor boards Null fields in the configuration sentence indicate no change in the particular...

Page 21: ...or board set position and time used for satellite acquisition Receipt of this sentence by the board set causes the software to restart the satellite acquisition process If there are no errors in the sentence it will be echoed upon receipt If an error is detected the echoed PGRMI sentence will contain the current default values Current PGRMI defaults can also be obtained by sending PGRMIE to the bo...

Page 22: ...rs 1 meter resolution 7 User earth datum delta y earth centered coordinate 5000 0 to 5000 0 meters 1 meter resolution 8 User earth datum delta z earth centered coordinate 5000 0 to 5000 0 meters 1 meter resolution 9 Differential mode A automatic output DGPS data when available non DGPS otherwise D differential exclusively output only differential fixes 10 NMEA Baud rate 1 1200 2 2400 3 4800 4 9600...

Page 23: ...eacon receiver 4 1 5 Output Sentence Enable Disable PGRMO The PGRMO sentence provides the ability to enable and disable specific output sentences The following sentences are enabled at the factory GPGGA GPGSA GPGSV GPRMC and PGRMT PGRMO 1 2 hh CR LF 1 Target sentence description e g PGRMT GPGSV etc 2 Target sentence mode where 0 disable specified sentence 1 enable specified sentence 2 disable all ...

Page 24: ...es the GPS 25LP to tune the beacon receiver 4 2 NMEA Transmitted Sentences The subsequent paragraphs define the sentences which can be transmitted on TXD1 by the GPS 25LP sensor boards 4 2 1 Sentence Transmission Rate Sentences are transmitted with respect to the user selected baud rate Regardless of the selected baud rate the information transmitted by the GPS 25LP is referenced to the one pulse ...

Page 25: ... set defaults will result in a once per second transmission at the NMEA specification transmission rate of 4800 baud 4 2 2 Transmitted Time The GPS 25LP sensor boards output UTC Coordinated Universal Time date and time of day in the transmitted sentences Prior to the initial position fix the date and time of day are provided by the on board clock After the initial position fix the date and time of...

Page 26: ...the leap second will be only 59 seconds long In this case the GPS 25LP will not transmit the time of day 23h 59m 59s for the day from which the leap second is removed 4 2 3 Global Positioning System Almanac Data ALM GPALM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 hh CR LF Almanac sentences are not normally transmitted Almanac transmission can be initiated by sending the sensor board a PGRMO GPALM 1 comm...

Page 27: ... in solution up to 12 transmitted leading zeros will be transmitted 4 Position dilution of precision 0 5 to 99 9 5 Horizontal dilution of precision 0 5 to 99 9 6 Vertical dilution of precision 0 5 to 99 9 4 2 6 GPS Satellites in View GSV GPGSV 1 2 3 4 5 6 7 4 5 6 7 hh CR LF 1 Total number of GSV sentences to be transmitted 2 Number of current GSV sentence 3 Total number of satellites in view 00 to...

Page 28: ...ds to true course 12 Mode indicator only output if NMEA 2 30 active A Autonomous D Differential E Estimated N Data not valid 4 2 8 Track Made Good and Ground Speed with GPS Talker ID VTG The GPVTG sentence reports track and velocity information with a checksum GPVTG 1 T 2 M 3 N 4 K 5 hh CR LF 1 True course over ground 000 to 359 degrees leading zeros will be transmitted 2 Magnetic course over grou...

Page 29: ...nd 000 to 359 degrees leading zeros will be transmitted 3 Speed over ground 000 0 to 999 9 knots leading zeros will be transmitted 4 Speed over ground 0000 0 to 1851 8 kilometers per hour leading zeros will be transmitted 5 Mode indicator only output if NMEA 2 30 active A Autonomous D Differential E Estimated N Data not valid 4 2 11 Estimated Error Information PGRME The GARMIN Proprietary sentence...

Page 30: ... value 4 2 13 Sensor Status Information PGRMT The GARMIN Proprietary sentence PGRMT gives information concerning the status of the sensor board This sentence is transmitted once per minute regardless of the selected baud rate PGRMT 1 2 3 4 5 6 7 8 9 hh CR LF 1 Product model and software version variable length field e g GPS 25LP VER 1 10 2 ROM checksum test P pass F fail 3 Receiver failure discret...

Page 31: ...pulse per second output is provided for applications requiring precise timing measurements The signal is generated after the initial position fix has been calculated and continues until power down The rising edge of the signal is synchronized to the start of each GPS second Regardless of the selected baud rate the information transmitted by the GPS 25LP sensor boards is referenced to the pulse imm...

Page 32: ... 104 format with message types 1 2 3 and 9 These corrections can be received by the GPS 25LP sensor board on RXD2 Correction data at speeds of 300 600 1200 2400 4800 or 9600 baud can be utilized as the GPS 25LP automatically detects the incoming baud rate For details on the SC 104 format refer to RTCM Paper 134 89 SC 104 68 by the Radio Technical Commission for Maritime Services ...

Page 33: ...d 11 ASTRONOMIC STATION 1952 Marcus Island 12 ASTRO B4 SOROL ATOLL Tern Island 13 BELLEVUE IGN Efate and Erromango Islands 14 BERMUDA 1957 Bermuda Islands 15 BOGOTA OBSERVATORY Colombia 16 CAMPO INCHAUSPE Argentina 17 CANTON ASTRO 1966 Phoenix Islands 18 CAPE CANAVERAL Florida Bahama Islands 19 CAPE South Africa 20 CARTHAGE Tunisia 21 CHATHAM 1971 Chatham Island New Zealand 22 CHUA ASTRO Paraguay ...

Page 34: ...land 49 MAHE 1971 Mahe Island 50 MARCO ASTRO Salvage Islands 51 MASSAWA Eritrea Ethiopia 52 MERCHICH Morocco 53 MIDWAY ASTRO 1961 Midway Island 54 MINNA Nigeria 55 NORTH AMERICAN 1927 Alaska 56 NORTH AMERICAN 1927 Bahamas excluding San Salvador Island 57 NORTH AMERICAN 1927 Central America Belize Costa Rica El Salvador Guatemala Honduras Nicaragua 58 NORTH AMERICAN 1927 Canal Zone 59 NORTH AMERICA...

Page 35: ...ay Peru Venezuela Trinidad and Tobago 85 SOUTH ASIA Singapore 86 PROVISIONAL SOUTH CHILEAN 1963 South Chile 87 SANTO DOS Espirito Santo Island 88 SAO BRAZ Sao Miguel Santa Maria Islands Azores 89 SAPPER HILL 1943 East Falkland Island 90 SCHWARZECK Namibia 91 SOUTHEAST BASE Porto Santo and Madeira Islands 92 SOUTHWEST BASE Faial Graciosa Pico Sao Jorge and Terceira Islands Azores 93 TIMBALAI 1948 B...

Page 36: ...wire U S A JAPAN J S T CORPORATION J S T MFG CO LTD 1957 South Lakeside Drive 6 8 2 chome Waukegan IL 60085 U S A Shigino nishi Phone 847 473 1957 Joto ku Fax G4 847 473 0144 Osaka 536 JAPAN Phone 06 968 6855 Fax G4 06 964 2085 A completely assembled connector with twelve inch pre stripped wires is available from GARMIN Corporation as part number 325 00026 00 Contact GARMIN for pricing and availab...

Page 37: ...reen displays the most recently received data in the sentence with the selected NMEA identifier highlighted in the top portion of the screen using the arrow keys The lower portion contains a formatted presentation of the currently selected sentence In addition to receiving data the program will also upload NMEA sentences to the sensor board The ALT U key sequence will upload the file NMEA TXT in t...

Page 38: ...2 Download almanc and ephemeris information upon command GPS25PM EXE can be invoked from a DOS prompt path gps25pm exe com x b yyyy Where denotes user supplied information denotes optional parameters x is com port number 1 or 2 default is 1 yyyy is baud rate 1200 2400 4800 or 9600 default is 9600 See Appendix D for detailed description and operation of the GPS25PM EXE program ...

Page 39: ... the same baud rate used for RTCM 104 data If the differential inputs are used on the GPS 25LP then the RTCM 104 data must be sent to the GPS 25LP at 9600 baud preferred or 4800 baud RTCM 104 baud rates less than 4800 baud are not supported by the GPS 25LP since it would limit bus bandwidth past the point where a once per second phase output data rate could be maintained Position Record 0x10 dle i...

Page 40: ...ouble pr unsigned int phase char slp_dtct unsigned char snr_dbhz char svid char valid cpo_rcv_sv_type typedef struct double rcvr_tow int rcvr_wn cpo_rcv_sv_type sv 12 cpo_rcv_type rcvr_tow Receiver time of week sec rcvr_wn Receiver week number cycles Number of accumulated cycles pr pseudo range mt phase to convert to 0 359 999 multiply by 360 0 and divide by 2048 0 slp_dtct 0 no cycle slip detecte...

Page 41: ...ue 256 int in_que_ptr 0 rx_state_type rx_state dat void add_to_que char data define dle_byte 0x10 define etx_byte 0x03 if rx_state dat if data dle_byte rx_state dle else in_que in_que_ptr data else if rx_state dle if data etx_byte rx_state etx else rx_state dat in_que in_que_ptr data else if rx_state etx if data dle_byte rx_state dle if in_que_ptr 255 in_que_ptr 0 ...

Page 42: ...ns the following information updated at once a second A Position 1 WGS 84 Latitude Longitude degrees minutes 0 0001 minute resolution 2 Ellipsoid Altitude meters 1 meter resolution B Velocity 1 Each of 3 axis meters per second 0 01 m s resolution 2 Altitude meters minute 1 mt m resolution 3 Ground Speed kilometers hour 0 1 km h resolution C Estimated Position Error Vertical Horizontal Total meters...

Page 43: ...l be over written P Position and Time Upload The program will prompt the user for the local time offset from UTC time This offset is then used to determine UTC time from the PC s real time clock The UTC time is then uploaded to the GPS25 sensor If an error occurs in the upload process a COMM ERROR will be enunciated on the screen After the UTC time has been uploaded the user is prompted for Latitu...

Page 44: ...uploading to the GPS25 sensor EPHEMERS DAT Example ephemeris entry Week 794 Ephemeris for PRN 18 Ref Time of Clk Parms s 233504 000000 Ref Time of Eph Parms s 233504 000000 Clk Cor Group Dly s 8 280389E 006 Clk Correction af1 s s 3 410605E 013 Clk Correction af2 s s s 0 000000E 000 User Range Accuracy m 33 299999 Eccentricity 5 913425E 003 SQRT A m 1 2 5 153628E 003 Mean Motion Cor r s 4 710911E 0...

Page 45: ...le w argument of perigee r double omg0 right ascension r double i0 inclination angle at reference time r float odot rate of right ascension r s float idot rate of inclination angle r s float cus argument of latitude correction sine r float cuc argument of latitude correction cosine r float cis inclination correction sine r float cic inclination correction cosine r float crs radius correction sine ...

Page 46: ...254110 RCV 31 45 T 170 2 21226528 82 2289074 RCV 22 42 T 315 9 22837584 50 1916778 RCV 27 36 T 132 4 24220207 85 2303835 RCV 14 39 T 127 4 25136106 23 1906158 PVT 235539 99999812 38 9499512 94 7463684 213 5 0 19 0 30 0 13 28 16 23 TIM 235540 99849199 794 RCV 18 50 T 174 9 19945258 21 2169465 RCV 29 50 T 177 7 20346113 87 2046190 RCV 28 45 T 159 6 21115834 07 2171514 RCV 19 47 T 324 7 21169868 61 2...

Page 47: ...43 GARMIN Corporation 1200 East 151st Street Olathe KS 66062 913 397 8200 913 397 8282 FAX 190 00125 00 Rev G ...