M7 GX Technical Manual
39
Raveon Technologies Corp.
GX radios. The GPS will normally output various NMEA messages from its serial
port. These NMEA messages from the external GPS must not be transmitted, or
the radio channel will become much too busy. The
RV-M7 GX
“mutes” its data
input when configured in GPS mode 4.
The
RV-M7 GX
will send position/status as well as transmit and receive serial data
when it is in GPS mode 2.
Serial Port Baud Rate
While the modem is transmitting, the user may continue to send more data into the
RV-M7.
Because the buffers in the RV-M7 are full-duplex, the serial port data rate
and the over-the-air data rates are independent. The serial port baud-rates may be
set slow to accommodate legacy equipment, or set at high-speed to minimize
latency. The over-the-air data rate us usually 4800 baud for narrow-band
channels, and 9600 baud for wide-band, although faster or slower rates may be
used.
6.7.
Data Reception
Serial Port Data
When the
RV-M7 GX
receives RS-232 data over the radio, it checks it for errors,
and if it is error-free, it will send it out the serial port. Again, the serial port may be
set to any baud rate the user wishes, and the radio receiver and transmitter will
continue to operate independently of the baud rate.
When the modem receives a radio signal, it will assert the CD hardware signal on
the RS-232 serial port if it was configured to do so.
GPS Position and Status
When the
RV-M7 GX
receives a position report and status from another
RV-M7
GX
, it will send this information out its RS-232 port, formatted as configured with
the
OUTPUT x
command. See Section 5.10 for detailed information on the type
and format of message output from the
RV-M7 GX
when a position/status report is
received from some other unit. Note, the
GPS x
command is a macro that sets
many parameters, one of which is the
OUTPUT
. When the GPS x command is
executed, it will set the OUTPUT setting to the appropriate message format for the
particular GPS mode. After the
GPS x
command is executed, you may then issue
the
OUTPUT x
command to modify the output protocol.
The position/status messages that the
RV-M7 GX
is able to send out of its serial
port are:
None
No position message output.
Output 0
disable the device from outputting
any message when a position report is received.
$PRAVE
Raveon Position & Status.
Output 1
This message is sent out of the
RV-M7
GX
when it is operating in the
GPS 2
mode. This message is used by third-
party and PC applications for tracking location and status information.
$GPTLL
NMEA Target Lat Long.
Output 2
T
his message is commonly sent by marine
RADAR receivers to notify plotting devices of the location of a RADAR target.