M7 GX Technical Manual
54
Raveon Technologies Corp.
Upon power up, the packet counter feature is always disabled.
10.7.
Tune-up and Alignment
Do not key the transmitter for more than 30 seconds out of
every 150 seconds if the RF power is set above 2 watts.
Radio calibration and alignment is performed using the
ATRx
commands. The
RV-
M7
modem has been factory calibrated, in should not require any re-calibration
when installed, or when changing frequency or channel. Unless the user is trained
in radio test and calibration, the values stored in the R registers should not be
modified.
Improper adjustment of the radio calibration (R0-R9 and RA registers), can
result in failure of the radio modem.
C
alibration and alignment values are stored internal to the modem in the “R”
registers. (R0-R9 and RA). For example, to read R5, issue the
ATR8
command
without any parameter. To change the setting, issue the
ATR8 nn
command,
where nn is the new value you would like to store.
Once you read a register using an ATRx command, you may modify its value by
entering a “U” for up or a “D” for down. U or D will change the value by one. Use
this trick carefully, because it modifies the last R register that was read, and it is
easy to unintentionally modify the wrong register.
Periodic Calibration
The only setting that may require adjustment is the center frequency. After years
of operation, all crystals will age and change frequency slightly. The ATR8
command is used to adjust the center frequency. Like all narrow-band radios,
semi-annual checks and adjustment of frequency is recommended.
Center Frequency
1. Key the transmitter with CW output using this command:
ATTD 7
2. The modem will now put out CW on the center of the channel.
3. Read the frequency offset with the
ATR8
command.
4. Adjust the frequency to the center of the channel with the
ATR8
command.
You can use the “U” key and the “D” key to change the settings up and
down one value in real time.
TX Deviation
1. Switch to channel 1.
2. Key the transmitter into a 50 ohm load using the
ATTD 3
command. The
unit will now transmit, and send a digital 0 continuously. This should be
+2.0kHz in frequency for narrow-band radios (12.5kHz spaced channels)
and +4.0kHz for wide-band (25kHz channels).
