Q-Flex Satellite Modem Installation and Operating Handbook
6-41
In addition, the modem’s internal high-stability oscillator can be slaved to the station clock
thereby ensuring its use in carrier and BUC/LNB control. Note that even when being
used in the IF frequency bands, the high-stability oscillator (normally regarded as an L-
band feature) can still be slaved to the station clock. The station clock frequency must be
at one of a small number of fixed frequencies when used to slave the high-stability
oscillator.
The options also allow the 10MHz reference to be output through the 50
Ω
BNC station
clock connector.
6.2.11.1 Station Clock Source
None
No station clock source has been selected.
BNC
The station clock input is provided via the rear-panel Station Clock BNC.
RS422
The station clock input is provided via the RS422 differential station clock
pins on the rear-panel Async ESC connector.
Table 6-47 Station Clock Source
When providing an external 10MHz clock to the modem, it must meet the following single
sideband phase noise measurements at various offset frequencies:
•
10 Hz: -125 dBc/Hz
•
100 Hz: -145 dBc/Hz
•
1kHz: -150 dBc/Hz
•
10 kHz: -155 dBc/Hz
•
100 kHz: -155 dBc/Hz
6.2.11.2 Station Clock Frequency
The actual station clock input frequency value must be input to the modem. Valid
frequency values will vary depending on whether the station clock is being used for
terrestrial clocking only or whether it is additionally used for carrier and/or BUC/LNB
control. The appropriate frequency input range will be automatically displayed.
Range:
1000kHz to 10000kHz; step size: 1kHz
Description:
This must reflect the actual frequency of the station clock input as the
modem does not automatically measure the frequency. It is used by the
modem in programming the terrestrial interface clocking logic.
Table 6-48 Station Clock Frequency (when not locking the high-stabiliy oscillator)
Options:
10MHz, 5MHz, 2MHz, 1MHz
