Comtech EF Data CDM-625 - Page 367

CDM-625 Advanced Satellite Modem Revision 13
DoubleTalk
Carrier-in-Carrier Option MN-CDM625
10–31
• Transponder Bandwidth = 36 MHz
• Power Available / MHz = 1995.26 / 36 = 55.424 W
• If a carrier uses 24 dBW, its PEB = 10
2.4
/ 55.424 = 4.532 MHz
This corresponds to 12.59% of available transponder power.
CnC Ratio
Ratio of Interfering Carrier Power to Desired Carrier Power (unit in dB).
The Interfering Carrier is the Tx Carrier from local modulator; the Desired Carrier is the carrier from the
distant end received by the local demodulator.
At the station transmitting C1: CnC Ratio (in dB) = PowerC1 (in dBm) – PowerC2 (in dBm)
Eb/No
Ratio of Energy per bit (Eb) to Noise density (No) (unit in dB):
• Eb/No = C/No – 10log(DR) [where DR is the Data Rate]
• Eb/No = Es/No – 10log(SE) [where SE is Spectral Efficiency]
Es/No
Ratio of Energy per symbol (Es) to Noise density (No) (unit in dB):
• Es/No = C/No – 10log(SR) [where SR is the Symbol Rate]
• Es/No = Eb/No + 10log(SE) [where SE is Spectral Efficiency]
C/N
Ratio of Carrier Power (C) to Noise (N) (unit in dB):
Equivalent to Es/No when calculated in the Symbol Rate bandwidth.
C/No
Ratio of Carrier Power (C) to Noise Density (N
o
) (unit in dBHz)