1. DL manuals
  2. Garmin
  3. GPS
  4. GPS 25 LP
  5. Technical Specification

Garmin GPS 25 LP Technical Specification

Manual is about: Garmin GPS 25 LP OEM/Sensors-engine: Technical Spec

Summary of GPS 25 LP

  • Page 1

    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

    ©2000 garmin corporation 1200 east 151st street, olathe, ks 66062 all rights reserved. No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of garmin...

  • Page 3: Table of Contents

    I table of contents table of contents ............................................................................................................. I section 1 ......................................................................................................................... 1 introduction.......

  • Page 4

    Ii 4.2.7 recommended minimum specific gps/transit data (rmc)................ 24 4.2.8 track made good and ground speed with gps talker id (vtg) ........... 24 4.2.9 geographic position with loran talker id (lcgll) .............................. 24 4.2.10 track made good and ground speed with loran t...

  • Page 5: Section 1

    1 section 1 introduction 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 u...

  • Page 6

    2 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

    3 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....

  • Page 8

    4 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 tm (almanac known, initial position an...

  • Page 9

    5 1.5 application gps 25lp series block diagram 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 gp...

  • Page 10

    6 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 perf...

  • Page 11: Section 2

    7 section 2 operational characteristics 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 boa...

  • Page 12

    8 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, thegps 25lp will begin ...

  • Page 13

    9 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 describ...

  • Page 14: Section 3

    10 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 corpo...

  • Page 15

    11 3.3 connector pin-out pin-out diagram 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. Electrically i...

  • Page 16

    12 pin 5: rxd1 - first serial asynchronous input. Rs-232 compatible with maximum input voltage range -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. Maximum load impedance is 4.7k oh...

  • Page 17

    13 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 connection...

  • Page 18

    14 3.4 antenna connection the gps 25lp sensor boards make their antenna connections via a 50 ohm mcx style connector attached directly to the sensor board (+vin-0.4v @ 15 ma power is supplied on the center conductor for the antenna). Coaxial cable supplies +vin-0.4v @15 ma to antenna/preamp. 1.57542...

  • 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: Section 4

    16 section 4 software interface the gps 25lp interface protocol design on txd1/rxd1 is based on the national marine electronics association’s nmea 0183 ascii interface specification, which is fully defined in “nmea 0183, version 2.0” (copies may be obtained from nmea, p.O. Box 50040, mobile, al, 366...

  • Page 21

    17 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. Number of current alm sentence. This field can be null or any number when sending almanac to the sensor board. Satellite prn ...

  • Page 22

    18 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. $pgrmc,,,,,,,,,,,,,,*hh >...

  • Page 23

    19 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,,*hh nmea output time 1-900 (sec). Binary phase output data, 1 = off, 2 = on. Position pinn...

  • Page 24

    20 3) if either the target sentence mode field or the target sentence description field is not valid, the pgrmo sentence will have no effect. 4) $pgrmo,gpalm,1 will cause the sensor board to transmit all stored almanac information. All other nmea sentence transmission will be temporarily suspended. ...

  • Page 25

    21 characters transmitted per sec baud characters_transmitted_per_sec 300 30 600 60 1200 120 2400 240 4800 480 9600 960 19200 1920 sentence max_characters gpgga 81 gpgsa 66 gpgsv 210 gprmc 74 gpvtg 42 pgrmb 26 pgrme 35 pgrmt 50 pgrmv 32 pgrmf 82 lcgll 44 lcvtg 39 the maximum number of fields allowed...

  • Page 26

    22 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 ...

  • Page 27

    23 gps quality indication, 0 = fix not available, 1 = non-differential gps fix available, 2 = differential gps (dgps) fix available, 6 = estimated number of satellites in use, 00 to 12 (leading zeros will be transmitted) horizontal dilution of precision, 0.5 to 99.9 antenna height above/below mean s...

  • Page 28

    24 4.2.7 recommended minimum specific gps/transit data (rmc) $gprmc,,,,,,,,,,,,*hh utc time of position fix, hhmmss format status, a = valid position, v = nav receiver warning latitude, ddmm.Mmmm format (leading zeros will be transmitted) latitude hemisphere, n or s longitude, dddmm.Mmmm format (lea...

  • Page 29

    25 latitude hemisphere, n or s longitude, dddmm.Mmmm format (leading zeros will be transmitted) longitude hemisphere, e or w utc time of position fix, hhmmss format status, a = valid position, v = nav receiver warning mode indicator (only output if nmea 2.30 active), a = autonomous, d = differential...

  • Page 30

    26 gps week number (0 - 1023) gps seconds (0 - 604799) utc date of position fix, ddmmyy format utc time of position fix, hhmmss format gps leap second count latitude, ddmm.Mmmm format (leading zeros will be transmitted) latitude hemisphere, n or s longitude, dddmm.Mmmm format (leading zeros will be ...

  • Page 31

    27 true east velocity, -514.4 to 514.4 meters/second true north velocity, -514.4 to 514.4 meters/second 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,,,,,,k* beacon tune frequency, 0.0...

  • Page 32

    28 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

    29 appendix a earth datums the following is a list of the garmin gps 25lp earth datum indexes and the corresponding earth datum name (including the area of application): 0 adindan - ethiopia, mali, senegal, sudan 1 afgooye - somalia 2 ain el abd 1970 - bahrain island, saudi arabia 3 anna 1 astro 196...

  • Page 34

    30 30 gandajika base - republic of maldives 31 geodetic datum 1949 - new zealand 32 ordnance survey of great britain 1936 - england, isle of man, scotland, shetland islands, wales 33 guam 1963 - guam island 34 gux 1 astro - guadalcanal island 35 hjorsey 1955 - iceland 36 hong kong 1963 - hong kong 3...

  • Page 35

    31 68 nahrwan - masirah island (oman) 69 nahrwan - saudi arabia 70 nahrwan - united arab emirates 71 observatorio 1966 - corvo and flores islands (azores) 72 old egyptian - egypt 73 old hawaiian - mean value 74 oman - oman 75 pico de las nieves - canary islands 76 pitcairn astro 1967 - pitcairn isla...

  • Page 36: Appendix B

    32 appendix b gps 25lp connectors the mating power/data connector is available from jst corporation, you may contact them for the current distributor nearest you. The information is listed below. Mating connector part number: housing: zhr-12 crimp contact: szh-002t-p0.5 (for 26 to 28 awg wire) szh-0...

  • Page 37: Appendix C

    33 appendix c gps 25lp evaluation kits 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 specifi...

  • Page 38

    34 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: gps25pm.E...

  • Page 39

    35 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...

  • Page 40

    36 lon 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...

  • Page 41

    37 dle and etx bytes: software written to receive the two records should filter dle and etx bytes as described below: typedef enum { dat, dle, etx } rx_state_type; char in_que[256]; int in_que_ptr = 0; rx_state_type rx_state = dat; void add_to_que( char data ) { #define dle_byte 0x10 #define etx_byt...

  • Page 42

    38 garmin phase monitor program - gps25pm.Exe command line arguments default: /com1 - selects which pc serial port to use for communication - com1, com2 (com1 default). /b:9600 - selects the baud rate - 1200, 2400, 4800, or 9600 (9600 default) description: gps25pm.Exe is designed to interface with a...

  • Page 43

    39 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. G...

  • Page 44

    40 file formats almanac.Dat example almanac entry: **** week 794 almanac for prn-01 ************ id: 01 health: 000 eccentricity: 3.414630890e-003 time of applicability(s): 380928.0000 orbital inclination(rad): 9.549833536e-001 rate of right ascen(r/s): -7.771752131e-009 sqrt(a) (m^1/2): 5153.589843...

  • Page 45

    41 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 /* ephemeris record */ { char svid; /*...

  • Page 46

    42 rcv 19 47 t 145.2 21190271.83 2182643 rcv 31 45 t 75.8 21240354.20 2216421 rcv 22 42 t 195.1 22849183.41 1855826 rcv 27 36 t 155.2 24234175.55 2230462 rcv 14 39 t 202.3 25147694.34 1845263 pvt 235537.99999842 38.9499588 94.7463684 211.7 -0.19 -0.31 0.13 28 16 23 tim 235538.99853500 794 rcv 18 50 ...

  • Page 47

    43 garmin corporation 1200 east 151st street olathe, ks 66062 (913)397-8200 (913)397-8282 fax 190-00125-00 rev. G.