Comtech EF Data CDM-750, Installation And Operation Manual

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CDM-750 Advanced High-Speed Trunking Modem Revision 2
Front Panel Operation MN-CDM750
5–47
Otherwise:
Rx-Params: EsNo=>23.5 dB ⌂ F=+005.0 kHz
MODCOD: QPSK ½ RxLevel= -31dBM
Note the following:
Item 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.
Δ
F The frequency offset of the received carrier, in kHz, with a displayed resolution of 100 Hz.
Rx-Level A dBm reading indicating the signal level of the desired receive carrier. Resolution: 0.5dB.
ModCod The current ModCod.
5.2.4.5 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. Note the
following:
•
The Monitor: CnC screen refreshes once every second.
•
CnC parameters need to be within the tolerances specified in Sect. 1.4.8 DoubleTalk
TM
Carrier ‐ in ‐ Carrier
®
(CnC) .
•
Ideal operation occurs when the CnC Ratio is 0 db. Ratios that are higher or lower –
approaching ±7 dB – will cause degradation. Ratios beyond ±7 dB may cause complete
unlock of circuit.
•
The Delay in a properly working CnC link is typically between 230 ms and 290 ms. Delay
when bench ‐ testing CnC operation is typically less than 100 µs.
5.2.4.6 Monitor: Stats (Statistics)
IP BasebandFraming Compression
34
Use the
W X
arrow keys to select IP, BasebandFraming , or Compression , and then press ENTER
.