Comtech EF Data CDM-760 - Manual (Page 137)

Front Panel Operation Revision 2
CDM-760 Advanced High-Speed Trunking Modem MN-CDM760
6–51
Parameter Description
Rx Modcod Displays the Rx ModCod.
LocEsNo Displays the EsNo of the local unit.
6.2.3.4 (Monitor:) Rx-Params (Rx Parameters)
When the demodulator is not locked, this read-only screen appears as follows:
Demodulator
Unlocked RxLevel= dBM
Otherwise:
Rx-Params: EsNo=>23.5 dB ⌂F=+005.0 kHz
ModCod: QPSK 1/2 RxLevel= -31dBM
Note the following:
Parameter Description
Es/No
The value of the Es/No calculated by the demodulator. Es/No is the Energy per Symbol
received (Es) divided by the Noise Spectral Density (No). Note that the Es/No reading assumes
that a linear, non-distorted carrier is being received. If a carrier is operating at or near saturation
and there are nonlinear distortions, the Es/No reading may be inaccurate, especially when
demodulating 16APSk and 32APSK carriers.
∆ F The frequency offset of the received carrier, in kHz, with a displayed step size of 100 Hz.
Rx-Level
A dBm reading indicating the signal level of the desired receive carrier, with a displayed step
size of 0.5dB.
ModCod The current ModCod.
6.2.3.5 (Monitor:) CnC (Carrier-in-Carrier Parameters)
CnC-Params: Freq-offset=-123.4kHz
Ratio:+1dB Delay=230.4ms
When enabled and locked, this read-only screen displays the CnC performance data:
• The Monitor: CnC screen refreshes once every second.
• CnC parameters must fall within the tolerances specified in Sect. 1.3.8 DoubleTalk TM Carrier-
in-Carrier ® (CnC).
• Ideal operation occurs when the CnC Ratio is 0 db. Ratios that are lower or higher –
approaching ±7 dB – will cause degradation. Ratios beyond ±7 dB may cause complete
unlock of circuit.