ITC 220 Base Station, Locomotive & Wayside Radio Transceiver Field Service Guide PN 0046300120 Rev. A
| Page 44
L1_TEST,SET,TXMOD,DQPSK
L1_TXDUTY,1000,300,0
where:
value
equals the desired frequency of operation.
Note:
The ratio of 300/1000 denotes a 30% transmit duty cycle. (The maximum transmit duty cycle for
Wayside Transceivers must be held to less than 10%. The ratio of 300/3500, you will see specified for the
Wayside Transceiver in the next section, denotes approximately a 9% transmit duty cycle.)
2.
With the transmitter keyed, monitor peak output power and make any necessary adjustments using the following
command in XtermW:
TXPOWER,value
where:
value
can be a positive (+) or negative (–) number in dB (resolution to 1/10
th
of a dB), depending on whether
you want to increase or decrease the power level.
3.
Once observation of radio performance is complete, turn off transmit operations by typing:
L1_TEST,STOP
To adjust RF output power for a Wayside Transceiver
Wayside Transceivers operate at half-rate π/4DQPSK modulation and are rated for a maximum duty cycle of 10%.
1.
Key up the transmitter for half-rate π/4DQPSK modulation using the following commands in XtermW:
STOP
SCHED,DEL,ALL
DSP_MODE,IDLE
DSP_MODE,TEST
L1_TEST,SET,TXFREQ,221137500
L1_TEST,SET,TXMOD,DQPSK_HALF
L1_TXDUTY,3500,300,0
where:
221137500
equals the desired frequency of operation in Hz.
Note:
The ratio of 300/3500, specified for Wayside Transceivers, denotes approximately a 9% transmit duty
cycle. (The maximum transmit duty cycle for Wayside Transceivers must be held to less than 10%.)
2.
With the transmitter keyed, monitor peak output power and make any necessary adjustments using the following
command in XtermW:
TXPOWER,value