Holux GM-270 User manual

CF GPS Receiver

Jul 05, 2002

User’s Guide

GM-270

TABLE OF CONTENTS

1. Introduction ……………………………………………………………………………………….. 3

1.1 Overview …………………………………………………………………………………….. 3

1.2 Features …………………………………………………………………………………….. 3

2. Brief Information ……………………………………………………………….………………… 5

2.1 Hardware Interface …………………………………………………………………………… 5

2.2 Software Interface …………………………………………………………………………… 6

3. Functional Test ………………………………………………………………………….…… 9

4. Trouble Shooting …………………………………………………………………………….… 12

5. Specifications ………………………………………………………………………………………. 13

6. Warranty ……………………………………………………………………………………………… 14

1. Introduction

1.1 Overview

1.2 Features

The GM-270 provides a host of features that make it easy for integration and use.

 12 parallel satellite-tracking channels for fast acquisition and reacquisition。

 High speed signal acquisition using 1920 time/frequency search channels.

 Built-in hardware Tracking Loop Processor WAAS/EGNOS Demodulator

 Low power consumption with Star II / LP chipset

 Built-in rechargeable battery for memory and RTC backup and for fast Time to First

Fix(TTFF)。

 Support NMEA0183 v2.2 data protocol and SiRF binary code。

 Trickle Power Enabled for Power Saving

 Enhanced algorithms -SnapLock and SnapStart provide superior navigation performance

in urban, canyon and foliage environments。

 Support CF card type I connector suitable PDA, Hand Held PC or PC device.。

LED

2. Brief Information

2.1 Hardware Interface

2.1.1 GM-270 Dimension

91 (L) x 50 (W) x 20 (H) mm

2.1.2 Hardware Interface

External Antenna

Connector

A. Link to PDA

B. Link to NoteBook

2.1.3 LED & External Antenna

◆LED

LED OFF GM-270 CF GPS Receiver Switch Off.

LED ON GM-270 CF GPS Receiver Signal Searching.

LED Flashing GM-270 CF GPS Receiver Signal Position Fixed.

◆External Antenna Connector (MCX)…..Optional

As using GM-270 CF GPS Receiver in a RV car, truck or bus, it might receive poor

signals through limited view to the sky. Replace the foldable antenna with the active one to

get better satellite signals. Windshields with heavy tinted or likewise may interfere with

signal receiving. An active antenna then becomes essential.

2.2 Software Interface

The GPS-270 interface protocol is based on the National Marine Electronics Association's NMEA 0183 ASCII

interface specification, which is defined in NMEA 0183, Version 2.2 and the Radio Technical Commission for Maritime

Services (RTCM Recommended Standards For Differential Navstar GPS Service, Version 2.1, RTCM Special Committee

No.104).

2.2.1 NMEA Transmitted Messages

The GPS-270PS supported by SiRF Technology Inc. also outputs data in NMEA-0183 format as defined by the

National Marine Electronics Association (NMEA), Standard.

The default communication parameters for NMEA output are 4800 baud, 8 data bits, stop bit, and no parity.

Table 2-1 NMEA-0183 Output Messages

NMEA Record Description

GGA Global positioning system fixed data

GSA GNSS DOP and active satellites

GSV GNSS satellites in view

RMC Recommended minimum specific GNSS data

•2.2.1.1 Global Positioning System Fix Data (GGA)

Table 2-2 contains the values for the following example:

$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M, , , ,0000*18

Table 2-2 GGA Data Format

Name Example Units Description

Message ID $GPGGA GGA protocol header

UTC Time 161229.487 hhmmss.sss

Latitude 3723.2475 ddmm.mmmm

N/S Indicator N N=north or S=south

Longitude 12158.3416 dddmm.mmmm

E/W Indicator W E=east or W=west

Position Fix Indicator 1 See Table 2-3

Satellites Used 07 Range 0 to 12

HDOP 1.0 Horizontal Dilution of Precision

MSL Altitude 9.0 Meters

Units M Meters

Geoid Separation Meters

Units M Meters

Age of Diff. Corr. second Null fields when DGPS is not used

Diff. Ref. Station ID 0000

Checksum *18

<CR> <LF> End of message termination

Table 2-3 Position Fix Indicator

Value Description

0 0 Fix not available or invalid

1 GPS SPS Mode, fix valid

2 Differential GPS, SPS Mode, fix valid

3 GPS PPS Mode, fix valid

2.2.1.2 GNSS DOP and Active Satellites (GSA)

Table 2-4 contains the values for the following example:

$GPGSA,A,3,07,02,26,27,09,04,15, , , , , ,1.8,1.0,1.5*33

Table 2-4 GSA Data Format

Name Example Units Description

Message ID $GPGSA GSA protocol header

Mode 1 A See Table 2-5

Mode 2 3 See Table 2-6

Satellite Used 07 Sv on Channel 1

Satellite Used 02 Sv on Channel 2

…… ….

Satellite Used Sv on Channel 12

PDOP 1.8 Position Dilution of Precision

HDOP 1.0 Horizontal Dilution of Precision

VDOP 1.5 Vertical Dilution of Precision

Checksum *33

<CR> <LF> End of message termination

1. Satellite used in solution.

Table 2-5 Mode 1

Value Description

M Manual—forced to operate in 2D or 3D mode

A2DAutomatic—allowed to automatically switch 2D/3D

Table 2-6 Mode 2

Value Description

1 Fix Not Available

2 2D

3 3D

2.2.1.3 GNSS Satellites in View (GSV)

Table 2-7 contains the values for the following example:

$GPGSV,2,1,07,07,79,048,42,02,51,062,43,26,36,256,42,27,27,138,42*71

$GPGSV,2,2,07,09,23,313,42,04,19,159,41,15,12,041,42*41

Table 2-7 GSV Data Format

Name Example Units Description

Message ID $GPGSV GSV protocol header

Number of Messages 2 Range 1 to 3

Message Number 1 Range 1 to 3

Satellites in View 07

Satellite ID 07 Channel 1 (Range 1 to 32)

Elevation 79 degrees Channel 1 (Maximum 90)

Azimuth 048 degrees Channel 1 (True, Range 0 to 359)

SNR (C/No) 42 dBHz Range 0 to 99, null when not tracking

.... ....

Satellite ID 27 Channel 4 (Range 1 to 32)

Elevation 27 degrees Channel 4 (Maximum 90)

Azimuth 138 degrees Channel 4 (True, Range 0 to 359)

SNR (C/No) 42 dBHz Range 0 to 99, null when not tracking

Checksum *71

<CR> <LF> End of message termination

NOTE: Items <4>,<5>,<6> and <7> repeat for each satellite in view to a maximum of four (4) satellites per sentence.

Additional satellites in view information must be sent in subsequent sentences. These fields will be null if unused.

2.2.1.4 Recommended Minimum Specific GNSS Data (RMC)

Table 2-8 contains the values for the following example:

$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598, ,*10

Table 2-8 RMC Data Format

Name Example Units Description

Message ID $GPRMC RMC protocol header

UTC Time 161229.487 hhmmss.sss

Status A A=data valid or V=data not valid

Latitude 3723.2475 ddmm.mmmm

N/S Indicator N N=north or S=south

Longitude 12158.3416 dddmm.mmmm

E/W Indicator W E=east or W=west

Speed Over Ground 0.13 knots

Course Over Ground 309.62 degrees True

Date 120598 ddmmyy

Magnetic Variation1 degrees E=east or W=west

Checksum *10

<CR> <LF> End of message termination

1.SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are geodetic

WGS84 directions.

2.2.2 RTCM Received Data

The default communication parameters for DGPS Input are 9600 baud, 8 data bits, stop bit, and no parity. Position

accuracy of less than 5 meters can be achieved with the GPS-270 by using Differential GPS (DGPS) real-time

pseudo-range correction data in RTCM SC-104 format, with message types 1,2, or 9. As using DGPS receiver with

different communication parameters, GPS-270 may decode the data correctly to generate accurate messages and save them

in battery-back SRAM for later computing.

3. Functional Test

◆Install Guide：

1. Install GPSViewer.exe from PC to your PDA(Microsoft Pocket PC OS or alike).

(1) Install Microsoft ActiveSync to your PC, refer to your Pocket PC manual for installation

procedure.

(2) Setup your Pocket PC cradle to Desktop PC UART port. The Microsoft ActiveSync will detect

your Pocket PC automatically.

(3) Double Click the GpsViewer.exe on your PC, then GpsViewer.exe program will install

automatically.

2. Push “Start”→”programs” bottom→“ GPS Viewer”

3. Push “Scan” bottom to scan your Com Port. Select your Com Port (COM 1〜COM 10)，

then push “Open GPS” bottom.

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