Comtech EF Data CDM-425, Инструкция по установке и эксплуатации

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CDM-425 Advanced Satellite Modem
Revision 0
Front Panel Operation 6–42 MN-CDM-425
6.2.1.8.2 CONFIG: CnC

CONFIG: CnC

Freq-Offset
CnC Frequency Offset: (range 1-032)
+/-015 kHz (

)
Use this menu to set the maximum expected frequency offset between the outbound interferer
and the desired inbound. It normally corresponds to the demod acquisition range.
Use the
▲▼ arrow keys to edit the CnC Frequency Offset value. Press
ENTER . The upper limit
of Frequency Offset is determined by the Rx symbol rate:
•
Below 64 ksymbols/sec: ±1 to ±(Rs/2) kHz, where:
Rs=symbol rate in ksymbols/sec
•
Between 64 and 389 ksymbols/sec: ± 1 up to a maximum of ± 32kHz
•
Above 389 ksymbols/sec: ±1 to ± (0.1Rs) kHz, up to a maximum of ± 200 kHz
This range is pre-calculated and displayed in parentheses for reference.
6.2.1.8.3 CONFIG: CnC

Search-Delay
CnC Search Delay: (range 0-330ms)
Min: 010 ms Max: 290 ms (

)
You may apply restrictions to the range of delay used by the search. This will reduce the time it
takes for the CnC algorithm to converge
Edit the Min or Max delay by using the
◄ ►
arrow keys to select a digit. Then, use the
▲▼ arrow
keys to change that digit. Press ENTER .
During initial link testing, you should set Min delay to 240 ms and Max delay to 300 ms . Once
CnC finds the exact delay, you can further reduce the values, but you must take care to allow
sufficient range to accommodate changes in path delay due to Doppler.
When you are bench-testing CnC with two units in a back-to-back configuration,
the minimum delay should be set to 0 ms, and the maximum to 20 ms. This takes
into account the lack of satellite delay.