USB GPS Receiver Series
Model:GT-3731R
Technical Manual
UniTraQ International Corp. All right reserved, © 2006
UniTraQ International Corp. RoHS compliance.
2007, Version 1.1
9F-2, No 158, Sec. 2, Gongdao 5th Rd., Hsinchu City 30070, Taiwan, R.O.C.
TEL：886-3-5710727 FAX：886-3-5751365
MADE IN TAIWAN
Eastern Star 7 series GT-3731R
GPS Receiver
Contents
1. Features…………………………………………………………………………………………………………...1
2. Specifications…………………………………………………………………………..…….…. ……………….2
3. GPS status indicator…………………………………………………………………………………………3
4. Communication specification……………………………………………………………….…………………..3
5. Environment specification………………………………………………….…….…….…………………..4
6. Pin assignment………………………………………………………………….…………………..4
7. Mechanic dimension…………………………………………………………………………………………….5
8. Customized package…………………………………………………………………………………………..5
9. Approved NMEA message…………………………………………….….……..………….………………….6
9.1 GGA – global positioning system fix data…………….………………………….….. ……………….6
9.2 GLL – latitude and longitude, with time of position fix and status……………… ………………..7
9.3 GSA - GPS DOP and active satellites…………….….….….….…….…..….….………………………..8
9.4 GSV - GPS satellite in view………….….….….….….…..….….….….….….……….………………….9
9.5 RMC – recommended minimum specific GPS/transit data…………. .….….…...…………………..10
9.6 VTG – course over ground and ground speed…………….….….….….……..….………………….11
9.7 ZDA – time and data…..….….….….….…..….….….….….….….….….…...….….….………………….11
9.8 Binary messages.….….….….….….…….….….….….….….….….….….….….….….………………….11
UniTraQ International Corp. RoHS compliance.
2007, Version 1.1
1. FEATURES
z 44 channels to acquire and track
satellites simultaneously
z Industry-leading TTFF speed
z Signal detection better than -158 dBm
z SBAS (WAAS/EGNOS) capable
z Cold start < 45sec
z Hot start < 1sec
z Accuracy 5m CEP
z USB Interface
z Easy-plug-in Notebook
z 49.8 mm x 43.7 mm x 17.6 mm
Eastern Star 7 series GT-3731R
GPS Receiver
GT-3731R
Fast Acquisition Enhanced Sensitivity
44 Channels USB Interface GPS Receiver
The GT-3731R is a compact all-in-one GPS receiver that
continuously tracks all satellites in view and provides
accurate satellite positioning data.
Its 44 parallel channels and 20000+ correlators provide fast
satellite signal acquisition and short start-up time. Acquisition
sensitivity of -155dBm and tracking sensitivity of -158 dBm
offer good performance even under difficult environments.
The GT-3731R is optimized for applications requiring good
performance and low cost; it is suitable for a wide range of
handhelds, asset tracking, Notebook, PDA-centric personal
navigation system, and vehicle navigation products.
z RoHS compliance
UniTraQ International Corp. RoHS compliance.
2007, Version 1.1
1
Eastern Star 7 series GT-3731R
2. SPECIFICATIONS
Parameter Specification
Receiver Typ e 44 channels
Re-acquisition sensitivity -155dBm
Tracking sensitivity -158dBm
Cold start sensitivity -137dBm
Receiver frequency 1575.42MHz
Code C/A code
GPS Receiver
Accuracy
(1) Position
(2) Velocity
Startup Time
hot start
warm start
cold start
Signal Reacquisition <1s
Update Rate 1Hz
Operational Limits
(1) Altitude
(2) velocity
Dynamics 4G (39.2m/sec2)
Datum WGS-84
Protocol NMEA-0183 V3.01
Serial Interface USB interface
5m CEP
0.1m/sec
< 1 sec
< 35 sec
< 45 sec
< 18,000m
< 500m/s
Input Volt age 5V ±5%
Power Consumption 180mW
Connector USB B-type 4P male connector with 1.8M cable
2
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
Eastern Star 7 series GT-3731R
GPS Receiver
3. GPS STAT US INDICATOR
The GT-3731R provides GPS status indicator. LED On board shows fix or non-fix. In fix mode, the LED
will light for 1second and turn off for 1second. In another mode, the pin will light for 2 seconds and turn off for
2 seconds.
4. COMMUNICATION SEPECIFICATIONS
Item Description
Interface Full duplex serial interface
Bit rate 4800/9600bps
Start bit 1bit
Stop bit 1bit
Data bit 8bit
Parity none
Transmission dat a SACII NMEA0183 Ver:3.01
Update rate 1Hz
Output sentence GGA/GSA/GSV/RMC
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2007, Version 1.1
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5. ENVIRONMENT SPECIFICATION
Parameter Specification
Eastern Star 7 series GT-3731R
GPS Receiver
Temperature
Operating
Storage
Humidity 5%~95%
-20℃~+60℃
-40℃~+80℃
6. PIN ASSIGNMENT
PIN Signal name Description Notes
1 VCC USB port power 5V
2 D- USB port data-
3 D+ USB port data+
4 GND USB ground
4
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
7. MECHANIC DIMENSION
Eastern Star 7 series GT-3731R
GPS Receiver
Parameter Specification
Physical dimension 49.8mm X 43.7mm X 17.6mm
Weight 14g
8. CUSTOMIZED PACKAGE
z Color box
z CD (including user manual, USB driver and GPS test program)
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
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Eastern Star 7 series GT-3731R
GPS Receiver
9. APPROVED NMEA MESSAGE
The serial interface protocol is based on the National Marine Electronics Association’s NMEA 0183 ASCII
interface specification. This standard is fully define in “NMEA 0183, Version 3.01” The standard may be
obtained from NMEA, www.nmea.org
9.1 GGA – GLOBAL POSITIONING SYSTEM FIX DATA
Time, position and fix related data for a GPS receiver.
Structure:
$GPGGA,hhmmss.sss,ddmm.mmmm,a,dddmm.mmmm,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh<CR><LF>
1 2 3 4 5 6 7 8 9 10 11 12 13
Example:
$GPGGA,060932.448,2447.0959,N,12100.5204,E,1,08,1.1,108.7,M,,,,0000*0E<CR><LF>
Field Name Example Description
1 UTC Time 060932.448 UTC of position in hhmmss.sss format, (000000.00 ~
2 Latitude 2447.0959 Latitude in ddmm.mmmm format
3 N/S Indicator N Latitude hemisphere indicator, ‘N’ = North, ‘S’ = South
4 Longitude 12100.5204 Longitude in dddmm.mmmm format
5 E/W Indicator E Longitude hemisphere indicator, 'E' = East, 'W' = West
6 GPS quality
indicator
7 Satellites Used 08 Number of satellites in use, (00 ~ 12)
8 HDOP 1.1 Horizontal dilution of precision, (00.0 ~ 99.9)
9 Altitude 108.7 mean sea level (geoid), (-9999.9 ~ 17999.9)
10 Geoid Separation Geoid separation in meters according to WGS-84 ellipsoid
11 DGPS Age Age of DGPS data since last valid RTCM transmission in
12 DGPS Station ID 0000 Differential reference station ID, 0000 ~ 1023
13 Checksum 0E
Note: The checksum field starts with a ‘*’ and consists of 2 characters representing a hex number. The
checksum is the exclusive OR of all characters between ‘$’ and ‘*’.
1 GPS quality indicator
235959.99)
Leading zeros transmitted
Leading zeros transmitted
0: position fix unavailable
1: valid position fix, SPS mode
2: valid position fix, differential GPS mode
3: GPS PPS Mode, fix valid
4: Real Time Kinematic. System used in RTK mode with
fixed integers
5: Float RTK. Satellite system used in RTK mode. Floating
integers
6: Estimated (dead reckoning) Mode
7: Manual Input Mode
8: Simulator Mode
(-999.9 ~ 9999.9)
xxx format (seconds)
NULL when DGPS not used
NULL when DGPS not used
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UniTraQ International Corp. RoHS compliance
2007, Version 1.1
Eastern Star 7 series GT-3731R
GPS Receiver
9.2 GLL - LATITUDE AND LONGITUDE, WITH TIME OF POSITION FIX AND STATUS
Latitude and longitude of current position, time, and status.
Structure:
$GPGLL,ddmm.mmmm,a,dddmm.mmmm,a,hhmmss.sss,A,a*hh<CR><LF>
1 2 3 4 5 6 7 8
Example:
$GPGLL,4250.5589,S,14718.5084,E,092204.999,A,A*2D<CR><LF>
Field Name Example Description
1 Latitude 4250.5589 Latitude in ddmm.mmmm format
Leading zeros transmitted
2 N/S Indicator S Latitude hemisphere indicator
‘N’ = North
‘S’ = South
3 Longitude 14718.5084 Longitude in dddmm.mmmm format
Leading zeros transmitted
4 E/W Indicator E Longitude hemisphere indicator
'E' = East
'W' = West
5 UTC Time 0922 04.999 UTC time in hhmmss.sss format (000000.00 ~ 235959.99)
6 Status A Status, ‘A’ = Data valid, ‘V’ = Data n ot valid
7 Mode Indicator A Mode indicator
‘N’ = Data not valid
‘A’ = Autonomous mode
‘D’ = Diffe rential mode
‘E’ = Estimated (dead reckoning) mode
‘M’ = Manual input mode
‘S’ = Simulator mode
8 Checksum 2D
7
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
Eastern Star 7 series GT-3731R
GPS Receiver
9.3 GSA - GPS DOP AND ACTIVE SA TELLITES
GPS receiver operating mode, satellites used in the navigation solution reported by the GGA or GNS
sentence and DOP values.
Structure:
$GPGSA,A,x,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,xx,x.x,x.x,x.x*hh<CR><LF>
1 2 3 3 3 3 3 3 3 3 3 3 3 3 4 5 6 7
Example:
$GPGSA,A,3,01,20,19,13,,,,,,,,,40.4,24.4,32.2*0A<CR><LF>
Field Name Example Description
1 Mode A Mode
‘M’ = Manual, forced to operate in 2D or 3D mode
‘A’ = Automatic, allowed to automatically switch 2D/3D
2 Mode 3 Fix type
1 = Fix not available
2 = 2D
3 = 3D
3 Satellite used 1~12 01,20,19,13,,,,,
,,,,
4 PDOP 40.4 Position dilution of precision (00.0 to 99.9)
5 HDOP 24.4 Horizontal dilution of precision (00.0 to 99.9)
6 VDOP 32.2 Vertical dilution of precision (00.0 to 99.9)
7 Checksum 0A
Satellite ID number, 01 to 32, of satellite used in solution,
up to 12 transmitted
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UniTraQ International Corp. RoHS compliance
2007, Version 1.1
Eastern Star 7 series GT-3731R
GPS Receiver
9.4 GSV - GPS SATELLITE IN VIEW
Number of satellites in view , PRN number, elevation angle, azimuth angle, and C/No. Four satellites details
are transmitted per message. Additional satellite in view information is send in subsequent GSV messages.
Structure:
$GPGSV,x,x,xx,xx,xx,xxx,xx,…,xx,xx,xxx,xx *hh<CR><LF>
1 2 3 4 5 6 7 4 5 6 7 8
Example:
$GPGSV,3,1,09,28,81,225,41,24,66,323,44,20,48,066,43,17,45,336,41*78<CR><LF>
$GPGSV,3,2,09,07,36,321,45,04,36,257,39,11,20,050,41,08,18,208,43*77<CR><LF>
Field Name Example Description
1 Number of message 3 Total number of GSV messages to be transmitted (1-3)
2 Sequence number 1 Sequence number of current GSV message
3 Satellites in view 09 Total number of satellites in view (00 ~ 12)
4 Satellite ID 28 Satellite ID number, GPS: 01 ~ 32, SBAS: 33 ~ 64 (33 =
PRN120)
5 Elevation 81 Satellite elevation in degrees, (00 ~ 90)
6 Azimuth 225 Satellite azimuth angle in degrees, (000 ~ 359 )
7 SNR 41 C/No in dB (00 ~ 99)
Null when not tracking
8 Checksum 78
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
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Eastern Star 7 series GT-3731R
GPS Receiver
9.5 RMC - RECOMMANDED MINIMUM SPECIFIC GPS/TRANSIT DATA
Time, date, position, course and speed data provided by a GNSS navigation receiver.
Structure:
$GPRMC,hhmmss.sss,A,dddmm.mmmm,a,dddmm.mmmm,a,x.x,x.x,ddmmyy,x.x,a,a*hh<CR><LF>
1 2 3 4 5 6 7 8 9 10 1112 13
Example:
$GPRMC,092204.999,A,4250.5589,S,14718.5084,E,0.00,89.68,211200,,A*25<CR><LF>
Field Name Example Description
1 UTC time 092204.999 UTC time in hhmmss.sss format (000000.00 ~
235959.999)
2 Status A Status
‘V’ = Navigation receiver warning
‘A’ = Data Valid
3 Latitude 4250.5589 Latitude in dddmm.mmmm format
Leading zeros transmitted
4 N/S indicator S Latitude hemisphere indicator
‘N’ = North
‘S’ = South
5 Longitude 14718.5084 Longitude in dddmm.mmmm format
Leading zeros transmitted
6 E/W Indicator E Longitude hemisphere indicator
'E' = East
'W' = West
7 Speed over ground 000.0 Speed over ground in knots (000.0 ~ 999.9)
8 Course over ground 000.0 Course over ground in degrees (000.0 ~ 359.9)
9 UTC Date 211200 UTC date of position fix, ddmmyy format
10 Magnetic variation Magnetic variation in degrees (000.0 ~ 180.0)
11 Magnetic Variation Magnetic variation direction
‘E’ = East
‘W’ = We st
12 Mode indicator A Mode indicator
‘N’ = Data not valid
‘A’ = Autonomous mode
‘D’ = Diffe rential mode
‘E’ = Estimated (dead reckoning) mode
‘M’ = Manual input mode
‘S’ = Simulator mode
13 checksum 25
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
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Eastern Star 7 series GT-3731R
GPS Receiver
9.6 VTG - COURSE OVER GROUND AND GROUND SPEED
The Actual course and speed relative to the ground.
Structure:
GPVTG,x.x,T,x.x,M,x.x,N,x.x,K,a*hh<CR><LF>
1 2 3 4 5 6
Example:
$GPVTG,89.68,T,,M,0.00,N,0.0,K,A*5F<CR><LF>
Field Name Example Description
1 Course 89.68 True course over ground in degrees (000.0 ~ 359.9)
2 Course Magnetic course over ground in degrees (000.0 ~ 359.9)
3 Speed 0.00 Speed over ground in knots (000.0 ~ 999.9)
4 Speed 0.00 Speed over ground in kilometers per hour (0000.0 ~
1800.0)
5 Mode A Mode indicator
‘N’ = not valid
‘A’ = Autonomous mode
‘D’ = Diffe rential mode
‘E’ = Estimated (dead reckoning) mode
‘M’ = Manual input mode
‘S’ = Simulator mode
6 Checksum 5F
9.7 ZDA -TIME AND DATE
Structure:
$GPRMC,hhmmss.sss,dd,mm.yyyy, , ,xxx<CR><LF>
1 2 3 4 5 6 7
Example:
$GPZDA,104548.04,25,03,2004,,*6C<CR><LF>
Field Name Example Description
1 UTC time 104548.04 UTC time in hhmmss.ss format, 000000.00 ~ 235959.99
2 UTC time: day 25 UTC time: day (01 ... 31)
3 UTC time: month 03 UTC time: month (01 ... 12)
4 UTC time: year 2004 UTC time: year (4 digit year)
5 Local zone hour
Not being output by the receiver (NULL)
6 Local zone minutes
Not being output by the receiver (NULL)
7 6C 6C Checksum
9.8 BINARY MESSAGES
See Binary Message Protocol User’s Guide for detailed descriptions.
UniTraQ International Corp. RoHS compliance
2007, Version 1.1
11
Eastern Star 7 series GT-3731R
GPS Receiver
UniTraQ International Corp
9F-2, No 158, Sec. 2, Gongdao 5th Rd., Hsinchu City 30070, Taiwan, R.O.C.
TEL：886-3-5710727 FAX：886-3-5751365
Email support@unitraq.com
Website www.unitraq.com
© 2006 UniTraQ International Corp. All rights reserved.
Not to be reproduced in whole or part for any purpose without written permission of UniTraQ International Corp (“UniTraQ”)
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