Installation guide

LMU Users Guide

V1.0.6 December 10 2009

- 63 - CalAmp Proprietary & Confidential

It is very important to note that the NMEA data produced by the LMU is not subject to

Pinning, therefore the position reported in a real-time mapping application may differ from

the position reported via LM Direct, or SMS.

9.4

9.4.1 Receiver Mode

Special Functions

The GPS receiver supports a number of ‘modes’ for tracking. The Receiver Mode controls

the GPS receiver’s internal filters. The looser the setting (i.e. High Dynamic Aircraft) the

noisier the position will be. It is best to choose the least dynamic environment setting that

will still track. That is, if the LMU is to be installed in a car, use the automotive setting. If the

LMU (i.e. the MTU-100) is on a person then use the pedestrian setting. The available

settings are:

• Stationary (1)

• Pedestrian (2)

• Automotive (3)

• At sea (4)

• Airborne low dynamics (5)

• Airborne medium dynamics (6)

• Airborne high dynamics (7)

The receiver mode is controlled by bits 0 – 2 of S-Register 139. To select a specific mode,

set these bits to the value referenced above. For example, so set the LMU to use the

Automotive GPS Receiver mode you would use:

AT$APP PARAM 1024,19,7,3

9.4.2 Enabling SBAS Support

A Satellite Based Augmentation System (SBAS) is a system that supports wide-area or

regional augmentation of GPS positioning through the use of additional satellite-broadcast

messages. Such systems are commonly composed of multiple ground stations, located at

accurately-surveyed points. The ground stations take measurements of one or more of the

satellites, the satellite signals, or other environmental factors which may impact the signal

received by the users. Using these measurements, information messages are created and sent

to one or more satellites for broadcast to the end users.

The LMU can enable the use of SBAS in the GPS Receiver by setting bit 4 of S-Register 139.

AT$APP PARAM 1024,19,16,16

9.4.3 Elevation Filter

The LMU’s Elevation Filter controls the minimum elevation a satellite needs to have for it to

be used in the GPS position calculation. The two options are a 15° filter and a 5° filter. The