User`s guide

Chapter 3 - Receiver Descriptions

SETTING UP RECEIVERS FOR SPECIFIC APPLICATIONS

M12+ as a Standard Autonomous Positioning Receiver

As supplied, the M12+ positioning receiver will work quite well without any operator intervention

except for enabling the desired output messages and a couple of setup steps. These are:

• Enabling the desired message strings (typically @@Ha or @@Hb, @@Bb, etc.)

• Setting the antenna Mask Angle using the @@Ag command. In the default condition the

M12+ positioning receiver's mask angle is set at 0

, but position accuracy will be

improved by setting this angle somewhere in the range of 5-10

. This is due to the fact

that the ionospheric correction algorithms used by the receiver are less accurate for low-

lying satellites.

• If NMEA operation is desired, this mode should be invoked using the @@Ci command.

Once in NMEA mode, any of the seven NMEA sentences may be enabled with the

appropriate commands as detailed earlier.

NOTE: Once in NMEA mode, you will be unable to

modify receiver operating parameters such as Mask

Angle, Satellite Ignore List, etc., nor will you be able

to access any of the receiver diagnostics such as

the Self-Test or the status bits in the @@Ha and

@@Hb messages. If you wish to use any of these

functions you must temporarily switch back to

binary mode, perform the desired operations, and

then switch back to NMEA protocol.

M12+ as a Positioning Receiver Using Differential Corrections

Setting up the M12+ for use as a differential 'rover' is identical to the setup shown above except

for a couple of minor additions:

• Disable the ionospheric and tropospheric corrections by invoking mode 0 in the @@Aq

Ionospheric Corrections Select Command. Having the corrections disabled in both the

rover and base station will cancel out the ionospheric delay, whereas the ionospheric

correction algorithm is not as accurate.

• Apply corrections to the receiver either through Port 1 or 2, depending upon the

correction format. Legal options are as follows:

1. M12+ rover receiver operating in Motorola binary mode - Apply Motorola binary

corrections from either a VP Oncore or M12+ Oncore Base Station to the main

serial port (Pin 2) using the @@Ce message, or apply RTCM-104 Type 1 or 9

corrections (from a Coast Guard beacon or other source) to the second serial

port on Pin 8. Corrections may be applied at 2400, 4800, or 9600 baud.

2. M12+ rover receiver operating in NMEA mode - Corrections MUST be in RTCM-

104 format and applied to the second serial port as detailed above.

Motorola GPS Products - M12+ User's Guide Revision 6.X 09FEB05