User's Manual

ITCR Locomotive Radio User Guide
© 2013 Meteorcomm LLC. All Rights Reserved. Proprietary and Confidential
10 Do Not Distribute 4/30/2013
5.3 Measure and Calibrate Reference Crystal Oscillator Frequency
The instructions below allow you to change the factory calibration settings for the
master reference oscillator crystal.
To check the master reference crystal oscillator frequency calibration:
1. Open an XtermW session.
2. Put the radio into test mode by typing:
dsp,watchdog,off
dsp_mode,test
3. Reduce output power to approximately 2W by typing:
cal,set,igain,-1000
cal,set,qgain,-1000
4. Begin transmitting a test tone offset +8kHz from the carrier:
dsp_mode,idle
dsp_mode,test
l1_test,stop
l1_test,set,txmod,cw
l1_test,set,txfreq,220012500
l1_test,start,tx
5. Use the frequency counter or frequency counting marker on the VSA to
measure the output frequency. The measured value is exactly 8 kHz greater
than the actual carrier frequency. The carrier frequency is normally well within
352 Hz (1.5 ppm) of the carrier frequency.
6. Alternate to the test tone: Substitute the following π/4-DQPSK modulation
command for the fourth line in step 4.
l1_test,set,txmod,dqpsk
7. Set the VSA to the center frequency of the channel and set it to demodulate
the 16 ksym/second π/4-DQPSK emission and measure the error frequency
which is referenced to the VSA center frequency.
8.