Table of Contents
Related Manuals for Garmin GPS 25 LP
Summary of Contents for Garmin GPS 25 LP
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Page 1: Technical Specification
GPS 25 LP SERIES 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 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.
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Page 3: Table Of Contents
Table of Contents ... i Section 1 ... 1 Introduction... 1 Overview... 1 Naming Conventions ... 1 Features ... 2 Technical Specifications... 3 1.4.1 Physical Characteristics ... 3 1.4.2 Environmental Characteristics... 3 1.4.3 Electrical Characteristics ... 3 1.4.4 Performance ... 4 1.4.5 Interfaces... - Page 4 Appendix A ... 29 Earth Datums... 29 Appendix B ... 32 GPS 25LP Connectors ... 32 Appendix C ... 33 GPS 25LP Evaluation Kits... 33 Appendix D ... 35 Phase Output Data Binary Format ... 35 GARMIN Phase Monitor Program - gps25pm.exe... 38...
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Page 5: Section 1
1.1 Overview The GARMIN GPS 25LP Series are GPS sensor boards designed for a broad spectrum of OEM (Original Equipment Manufacturer) system applications. The GPS 25LPs will simultaneously track up to twelve satellites providing fast time-to-first-fix, one second navigation updates and low power consumption. Their far-reaching capability meets the sensitivity requirements of land navigation as well as the dynamics requirements of high performance aircraft. -
Page 6: Features
Low Voltage - GPS25-LVx designation indicates that the unit is designed to operate from a low voltage 3.6VDC to 6.0VDC supply. Operation at about 4VDC is the most power efficient mode of operation for the GPS25LP sensor. The unit is protected if a high voltage is inadvertently applied to the input. -
Page 7: Technical Specifications
10) Flexible input voltage levels of 3.6Vdc to 6.0Vdc with overvoltage protection in the -LVx, and 6.0Vdc to 40Vdc in the -HVx versions. 11) Fully shielded construction for maximum EMI and RFI protection 12) FLASH based program memory. New software revisions upgradeable through serial interface 1.4 Technical Specifications Specifications are subject to change without notice. -
Page 8: Performance
1.4.4 Performance 1) Tracks up to 12 satellites (up to 11 with PPS active) 2) Update rate: 1 second 3) Acquisition time - 15 seconds warm (all data known) - 45 seconds cold (initial position, time and almanac known, ephemeris unknown) - 1.5 minutes AutoLocate - 5 minutes search the sky (no data known) 4) Position accuracy:... -
Page 9: Application
1.5 Application TYPICAL APPLICATION ARCHITECTURE 1.5.1 Application Considerations 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. - Page 10 recommended since it may cause rapid temperature changes which may temporarily affect the frequency stability of the internal oscillator. 3) Interruptions 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.
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Page 11: Section 2
This section describes the basic operational characteristics of the GPS 25LP sensor boards. Additional information regarding input and output specifications are contained in Section 4. 2.1 Self Test After input power has been applied to the GPS 25LP sensor boards and periodically thereafter, the units will perform critical self test functions and report the results over the output channel(s). -
Page 12: Navigation
1) Transportation over distances further than 1500 kilometers 2) Failure of the on-board memory battery 3) Stored date/time off by more than 30 minutes See Section 4 for more information on initializing the GPS 25LP. 2.3 Navigation After the acquisition process is complete, the GPS 25LP will begin sending valid navigation information over its output channels. - Page 13 a navigation solution. However, the host system should allow the board set to remain on for at least 12.5 minutes after the first satellite is acquired (see Section 4 for more information on status indications). 2) If the memory backup battery fails, the sensor board will search the sky as described above.
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Page 14: Section 3
Section 3 Hardware Interface 3.1 Mechanical Dimensions 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: Connector Pin-Out
3.3 Connector Pin-Out The following is a functional description of each pin of the interface connector. The pins are numbered from left to right as viewed from the connector end of the board with the connector on top. Pin 1: TXD2 - Second Serial Asynchronous Output. - Page 16 Pin 5: RXD1 - First Serial Asynchronous Input. RS-232 compatible with maximum input voltage range -25 < V < 25. directly connected to standard 3 to 5Vdc CMOS logic. The minimum low signal voltage requirement is 0.8V, and the maximum high signal voltage requirement is 2.4V.
- Page 17 Typical Embedded Application Interconnect For embedded applications where the sensor board will be connected directly 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.
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Page 18: Antenna Connection
Coaxial cable supplies +Vin-0.4V @15 mA to antenna/preamp. 1.57542 GHz signal returns to the sensor board. The recommended GARMIN remote antenna for the GPS 25LP series is the GA27. It has eight feet of RG-174A/U type cable with a MCX connector installed for attachment to the sensor board. - Page 19 Type RG-211A/228A RG-217/224/293/14 RG-8/215/216 RG-6 RG-59 RG-58 RG-188 RG-174 RG-178 Typical Attenuation dB/100’ @ 1 GHz 11.5...
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Page 20: Section 4
RTCM, P.O. Box 19087, Washington, D.C., 20036, U.S.A.). The GPS 25LP interface protocol, in addition to transmitting navigation information as defined by NMEA 0183, transmits additional information using the convention of GARMIN proprietary sentences. Binary phase data information is output on TXD2, see Appendix D for details. -
Page 21: Sensor Initialization Information
<1> Total number of ALM sentences to be transmitted by the sensor board during almanac download. This field can be null or any number when sending almanac to the sensor board. <2> Number of current ALM sentence. This field can be null or any number when sending almanac to the sensor board. -
Page 22: Additional Sensor Configuration Information (Pgrmc1)
between power cycles. The GPS 25LP will echo this sentence upon its receipt if no errors are detected. If an error is detected, the echoed PGRMC sentence will contain the current default values. Current default values can also be obtained by sending $PGRMCE to the board. -
Page 23: Output Sentence Enable/Disable
if no errors are detected. If an error is detected, the echoed PGRMC1 sentence will contain the current default values. Current default values can also be obtained by sending $PGRMC1E to the board. $PGRMC1,<1>,<2>*hh<CR><LF> <1> NMEA output time 1-900 (sec). <2>... -
Page 24: Tune Dgps Beacon Receiver (Pslib)
All other NMEA sentence transmission will be temporarily suspended. 4.1.6 Tune DGPS Beacon Receiver (PSLIB) The $PSLIB sentence provides the ability to tune a GARMIN GBR-21 or equivalent beacon receiver. $PSLIB,<1>,<2>*hh<CR><LF> <1> Beacon tune frequency, 0.0, 283.5 – 325.0 kHz in 0.5 kHz steps <2>... -
Page 25: Transmitted Time
Baud characters_transmitted_per_sec 1200 2400 4800 9600 19200 1920 Sentence max_characters GPGGA GPGSA GPGSV GPRMC GPVTG PGRMB PGRME PGRMT PGRMV PGRMF LCGLL LCVTG The maximum number of fields allowed in a single sentence is 82 characters including delimiters. Values in the table include the sentence start delimiter character “$” and the termination delimiter <CR><LF>. -
Page 26: Global Positioning System Almanac Data (Alm)
and time of day for leap second correction follow the guidelines in “National Institute of Standards and Technology Special Publication 432 (Revised 1990)” (for sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402, U.S.A.). When a positive leap second is required, the second is inserted beginning at 23h 59m 60s of the last day of a month and ending at 0h 0m 0s of the first day of the following month. -
Page 27: Gps Dop And Active Satellites (Gsa)
<6> GPS quality indication, 0 = fix not available, 1 = Non-differential GPS fix available, 2 = Differential GPS (DGPS) fix available, 6 = Estimated <7> Number of satellites in use, 00 to 12 (leading zeros will be transmitted) <8> Horizontal dilution of precision, 0.5 to 99.9 <9>... -
Page 28: Recommended Minimum Specific Gps/Transit Data (Rmc)
4.2.7 Recommended Minimum Specific GPS/TRANSIT Data (RMC) $GPRMC,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,<10>,<11>,<12>*hh<CR><LF> <1> UTC time of position fix, hhmmss format <2> Status, A = Valid position, V = NAV receiver warning <3> Latitude, ddmm.mmmm format (leading zeros will be transmitted) <4> Latitude hemisphere, N or S <5>... -
Page 29: Track Made Good And Ground Speed With Loran Talker Id (Lcvtg)
<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 $PGRME reports estimated position error information. $PGRME,<1>,M,<2>,M,<3>,M*hh<CR><LF> <1>... -
Page 30: Sensor Status Information
<15> Time dilution of precision, 0 to 9 (rounded to nearest integer 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. -
Page 31: Dgps Beacon Information
True north velocity, -514.4 to 514.4 meters/second <3> Up velocity, -999.9 to 9999.9 meters/second 4.2.15 DGPS Beacon Information (PGRMB) The GARMIN proprietary sentence $PGRMB reports DGPS beacon information. $PGRMB,<1>,<2>,<3>,<4>,<5>,K*<CR><LF> <1> Beacon tune frequency, 0.0, 283.5 – 325.0 kHz in 0.5 kHz steps <2>... -
Page 32: Rtcm Received Data
4.5 RTCM Received Data Position accuracy of less than 5 meters can be achieved with the GPS 25LP by using Differential GPS (DGPS) real-time pseudo-range correction data in RTCM SC-104 format, with message types 1, 2, 3, and 9. These corrections can be received by the GPS 25LP sensor board on RXD2. -
Page 33: Appendix A
The following is a list of the GARMIN GPS 25LP earth datum indexes and the corresponding earth datum name (including the area of application): ADINDAN - Ethiopia, Mali, Senegal, Sudan AFGOOYE - Somalia AIN EL ABD 1970 - Bahrain Island, Saudi Arabia... - Page 34 GANDAJIKA BASE - Republic of Maldives GEODETIC DATUM 1949 - New Zealand ORDNANCE SURVEY OF GREAT BRITAIN 1936 - England, Isle of Man, Scotland, Shetland Islands, Wales GUAM 1963 - Guam Island GUX 1 ASTRO - Guadalcanal Island HJORSEY 1955 - Iceland HONG KONG 1963 - Hong Kong INDIAN - Bangladesh, India, Nepal INDIAN - Thailand, Vietnam...
- Page 35 NAHRWAN - Masirah Island (Oman) NAHRWAN - Saudi Arabia NAHRWAN - United Arab Emirates OBSERVATORIO 1966 - Corvo and Flores Islands (Azores) OLD EGYPTIAN - Egypt OLD HAWAIIAN - Mean Value OMAN - Oman PICO DE LAS NIEVES - Canary Islands PITCAIRN ASTRO 1967 - Pitcairn Island PUERTO RICO - Puerto Rico, Virgin Islands QATAR NATIONAL - Qatar...
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Page 36: Appendix B
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 availability. An MCX terminated RF cable pig-tail assembly is also available from GARMIN Corporation as part number 320-00048-00. Appendix B... -
Page 37: Appendix C
GPS 25LP evaluation materials kit (part number 010-10197-00) is available from GARMIN international. This kit includes two DB-9 connectors with solder pots, GA27A GPS antenna with various mounting brackets, two 12 inch 12 conductor connectors, technical specification, and software to monitor the GPS 25LP outputs and configure the receiver. - Page 38 The Garmin Phase Monitor Program, GPS25PM.EXE, provides the following functions: - Display and log phase data output from TXD2 - Upload almanac, position, and time information via RXD2 - Download almanc and ephemeris information upon command GPS25PM.EXE can be invoked from a DOS prompt: <path>gps25pm.exe [/com<x>] [/b:<yyyy>]...
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Page 39: Appendix D
Phase Output Data Binary Format Two records are transmitted once per second by the GPS 25LP. One record contains primarily post- process information such as position and velocity information. The second record contains receiver measurement information. The records are sent at a default baud rate of 9600 baud, 8 bits, no parity. Records begin with a delimiter byte (10 hex). - Page 40 Longitude (rad) lon_vel Longitude velocity (mt/sec) lat_vel Latitude velocity (mt/sec) alt_vel Altitude velocity (mt/sec) Receiver Measurement Record - 0x10 (dle is first byte) - 0x29 (receiver record identifier) - 0xE2 (size of data) - cpo_rcv_type (see below) - one byte chksum (the addition of bytes between the delimiters should equal 0) - 0x10 (dle)
- Page 41 dle and etx bytes: Software written to receive the two records should filter dle and etx bytes as described below: typedef enum dat, dle, } rx_state_type; char in_que[256]; in_que_ptr = 0; rx_state_type rx_state = dat; void add_to_que( char data ) #define dle_byte 0x10 #define...
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Page 42: Garmin Phase Monitor Program - Gps25Pm.exe
- selects the baud rate - 1200, 2400, 4800, or 9600 (9600 default) Description: GPS25PM.EXE is designed to interface with a Garmin GPS 25 XL or GPS 25LP sensor boards and the GPS 35LP sensors. The program will perform the following functions: - display and log phase data output by GPS sensors. - Page 43 E. Accumulated Cycles (cycles) - 1 cycle resolution. The bottom section contains program messages. Upload and download status messages will appear here as well as any program error messages. Commands: D - Download Almanac: The GPS25 sensor will be sent a command to download almanac information. GPS25PM.EXE will create the file ALMANAC.DAT and locate it the current working directory.
- Page 44 File Formats ALMANAC.DAT Example almanac entry: **** Week 794 almanac for PRN-01 ************ Health: Eccentricity: Time of Applicability(s): Orbital Inclination(rad): Rate of Right Ascen(r/s): SQRT(A) (m^1/2): Right Ascen at TOA(rad): Argument of Perigee(rad): Mean Anom(rad): Af0(s): Af1(s/s): week: Almanac information for satellites with a bad health status will not be included in this file when downloaded from the GPS25 sensor and should not be included when uploading to the GPS25 sensor.
- Page 45 Ephemeris Record - 0x10 (dle is first byte) - 0x2A (ephemeris record identifier) - 0x74 (size of data) - eph_type (see description below) - one byte chksum (the addition of bytes between the delimiters should equal 0) - 0x10 (dle) - 0x03 (etx) typedef struct...
- Page 46 RCV 19 47 T 145.2 21190271.83 RCV 31 45 T 75.8 21240354.20 RCV 22 42 T 195.1 22849183.41 RCV 27 36 T 155.2 24234175.55 RCV 14 39 T 202.3 25147694.34 PVT 235537.99999842 38.9499588 TIM 235538.99853500 RCV 18 50 T 38.8 19958107.10 RCV 29 50 T 132.4 20358247.54...
- Page 47 GARMIN Corporation 1200 East 151st Street Olathe, KS 66062 (913)397-8200 (913)397-8282 FAX 190-00125-00 Rev. G...