Comtech EF Data CDM-570A - Manual (Page 196)

CDM-570A/570AL Satellite Modem with Optional Packet Processor MN-CDM570A
Ethernet-based Remote Product Management Revision 2
7–28
Carrier-in-Carrier (CnC)
Appendix G. D OUBLE T ALK C ARRIER - IN -C ARRIER (CnC) OPTION
When CDM-570 Compatibility Mode is selected using the ‘Configuration | Utilities’
page (Sect. 7.4.3.3.8), CnC is UNAVAILABLE and this page section becomes
nonfunctional.
• Mode – Use the drop-down list to set your desired CnC operating mode (Off, Normal, or
CnC-APC variants).
• Search Delay Range – Enter minimum and maximum values, in ms.
To reduce the time taken for the CnC algorithm to converge, you may apply restrictions to
the range of delay used by the search. During initial link testing, you should set the delay to
a minimum of 240 ms and a maximum of 300 ms. Once CnC has found the exact delay, the
value can be further reduced but care should be taken to allow sufficient range to
accommodate changes in path delay due to Doppler.
If bench-testing CnC with two units in a back-to-back configuration, you
should set the minimum delay to 0 ms, and the maximum delay to 20 ms. This
takes into account the lack of satellite delay.
• Freq Offset Range – This range is pre-calculated. The Rx symbol rate determines the CnC
Frequency Offset:
o From 16 to 64 ksymbols/sec (ksps): ±1 to the symbol rate (ksps/2)
o 64 ksps and above: ±1 to 32kHz
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