User`s guide

Section 9: GPS Settings

 The modem’s GPS reporting frequency determines the cellular network bandwidth

consumption. A higher reporting frequency will result in higher bandwidth

consumption.

The 5200 and 5600/A modems have an embedded GPS receiver which can be used to track

their movement. This feature is commonly used in applications such as asset-tracking and

Automatic Vehicle Location (AVL). These modems support two protocols: the National Marine

Electronics Association (NMEA) protocol and the Trimble ASCII Interface Protocol (TAIP).

The modem can report the fixes acquired from its GPS receiver to the local serial port, and/or

to an IP address, either local (Ethernet/USB) or remote (over the air). A variety of reporting

options are available, ranging from basic NMEA/TAIP timer-based reports to intelligent

condition-triggered reports which leverage the modem's Event Reporting capabilities.

TAIP protocol

TAIP is the more complex of the two GPS protocols, allowing greater control over the report

contents. It is configured using a single command string. Read Trimble’s TAIP documentation

to learn to create a command that meets your needs and for report parsing information. The

document is available here:

http://www.bluetreewireless.com/extranet/documents/Trimble_ASCII_Interface_Protocol.pdf

The modem listens on UDP port 21000 for TAIP commands, allowing its configuration to be

modified on the fly by software applications that support TAIP.

NMEA protocol

NMEA uses one or more of the following seven pre-defined, fixed-format messages.

Message Contents Size

GGA Time, position, and various status information 75 bytes

GLL Latitude, longitude, and time 48 bytes

GSA GPS DOP and active satellites 63 bytes

GSV Active satellites in view 70 bytes

RMC Time, date, position, course, and speed 67 bytes

VTG Track made good and ground speed 37 bytes

ZDA Time and date 35 bytes

Table 9

Refer to Trimble’s NMEA 0183 documentation for additional information. It is available here:

http://www.bluetreewireless.com/extranet/documents/NMEA_0183.pdf