The TR270 defaults to full duplex operation, which
permits monitoring the transmitted signal on the down-
link during transmit on the uplink frequency. The opera-
tion is always full duplex in the data mode.
As mentioned earlier, the TR270 will automatically track
the Doppler shift and correct the frequency of receiver
‘B’. To enable this feature, once the initial frequency is
tuned and a relative tuning indication number between
‘45’ and ‘55’ is displayed, press the
6
SAT
button. The
‘SCAN’ indicator will illuminate and the upper right (lock)
symbol will illuminate continuously. Now, as the downlink
frequency changes, the TR270 will automatically tune
the frequency of receiver ‘B’ to track the changing
frequency. If the signal fades, a scan will initiate and the
receiver will hunt to acquire the carrier again. At this
time, the (lock) symbol will flash to indicate a loss of lock
on the downlink signal. When the scan sequence
acquires the downlink signal, the relative tuning indica-
tion will again read ‘50’ and the (lock) symbol will
illuminate continuously.
After LOS, the TR270 will begin scanning through a
programmed frequency range anticipating the next
satellite pass.
The range is programmed within SETUP #53. The indi-
cated number may be set from ‘00’ through ‘99’ (0 to ±
-99 kHz, in 1 kHz increments). The factory default setting
is ‘10’ (±10 kHz scanning range of center frequency).
The scan pause time, which is the time between fre-
quency updates, is programmed within SETUP #54. The
indicated number may be set from ‘00’ through ‘99’ (0
through 9.9 seconds, in 0.1 second increments. The
factory default setting is ‘05’ (0.5 second).
The scan resume time, which is the delay time between
the end of a satellite locked condition and the resuming
of satellite scan, is programmed within SETUP #55. The
indicated number may be set from ‘00’ through ‘99’ (0
through 99 seconds, in 1 second increments). The
factory default setting is ‘05’ (5 seconds).
The receiver’s front panel display will indicate TNC status,
for example: XMT,DCD, etc.
To exit the SAT mode, press the
2
VFO
button.
36 Satellite Operation, continued