Comtech EF Data CDM-625A - Manual (Page 156)

CDM-625A Advanced Satellite Modem MN-CDM625A
Front Panel Operation Revision 3
6–30
When you select IESS, the default ITU V.35 scrambler specified in IESS-315 takes priority over all
“normal” scramblers and is used instead. Therefore, for many operating modes, the two
scrambler selections are redundant.
When using TPC and Carrier-in-Carrier simultaneously, the IESS-315 (V.35) scrambler is the only
permitted choice.
6.2.1.4.8 CONFIG: Rx  Eq (Equalizer)
Rx Equalizer:
Disabled (Enable,Disable) ()
Use the ▲▼ arrow keys to select Enable or Disable. Press ENTER. The integrated 5-tap adaptive
equalizer can compensate for:
• Amplitude slope and variation over the symbol bandwidth.
• Non-linear group delay variation over the symbol bandwidth.
The Rx Equalizer is particularly useful at higher symbol rates (up to 12.5 Msymbols/second) in
situations with long cable runs between equipment (downconverter and modem, for example).
The Eb/No estimate is performed after the adaptive equalizer block, which provides an easy way
to determine if the equalizer is providing any benefit. If the equalizer is first turned off, the
Eb/No may be viewed on the monitor screen. The equalizer is then turned on, and the Eb/No
viewed on the monitor screen to determine any improvement.
6.2.1.4.9 CONFIG: Rx  EbNo
Receive EbNo Alarm Point = 02.0 dB
()
Edit the EbNo Alarm Point by using the ◄ ► arrow keys to select a digit, and then using the ▲▼
arrow keys to change that digit. The allowable range is from 00.1 to 16.0 dB. Press ENTER.
If the Rx Eb/No falls below this value and the fault is NOT masked, a receive traffic
fault will be generated.
6.2.1.4.10 CONFIG: Rx  SNR (IP-ACM or V2-ACM Modes Only)
Receive SNR Alarm Point = 00.1 dB
()
When either ACM mode is active, the CONFIG: Rx menu changes the EbNo option to SNR.