DS-41BTM-1 Feb ’06

©2006 RF Solutions Ltd, www.rfsolutions.co.uk

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GPS Receiver Module

GPS-41BTM

Li-ION BATTERY CHARGER OPERATION

While the UT-41BTM is connected to the Li-ION rechargeable battery only, without the external 5V DC power

source, the red battery-low LED indicator will turn ON when output voltage of the Li-ION falls below 3.45V.

When the 5V DC source is connected to charge the Li-ION battery, the green charging-battery LED indicator

will turn ON. The battery will be charging at 48mA during the pre-charge phase until 2.93V is reached. Next,

charge current changes to 480mA during the full-charge phase until 4.1V is reached. Afterwards, charge

current will decrease gradually until 48mA is reached, and the charge current will fall to a very low value and

remain in the trickle charge phase. The green charging-battery LED indicator remains ON until the 5V DC

source is disconnected.

MEA Messages

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

GGA - GPS FIX DATA

Time, position and position-fix related data (number of satellites in use, HDOP, etc.).

Format:

$GPGGA,<1>,<2>,<3>,<4>,<5>,<6>,<7>,<8>,<9>,M,<10>,M,<11>,<12>,*<13><CR><LF>

Example:

$GPGGA,104549.04,2447.2038,N,12100.4990,E,1,06,01.7,00078.8,M,0016.3,M,,*5C<CR><LF>

Field

Example

Description

1

104549.04 UTC time in hhmmss.ss format, 000000.00 ~ 235959.99

2

2447.2038 Latitude in ddmm.mmmm format

Leading zeros transmitted

3

N

Latitude hemisphere indicator, ‘N’ = North, ‘S’ = South

4

12100.4990 Longitude in dddmm.mmmm format

Leading zeros transmitted

5

E

Longitude hemisphere indicator, 'E' = East, 'W' = West

6

1

Position fix quality indicator

0: position fix unavailable

1: valid position fix, SPS mode

2: valid position fix, differential GPS mode

7

06

Number of satellites in use, 00 ~ 12

8

01.7

Horizontal dilution of precision, 00.0 ~ 99.9

9

00078.8

Antenna height above/below mean sea level, -9999.9 ~ 17999.9

10

0016.3

Geoidal height, -999.9 ~ 9999.9

11

Age of DGPS data since last valid RTCM transmission in xxx format (seconds)

NULL when DGPS not used

12

Differential reference station ID, 0000 ~ 1023

NULL when DGPS not used

13

5C

Checksum

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 ‘*’.