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CDM-Qx Satellite Modem Revision 5
CnCPerformance Characterization MN/CDMQx.IOM
D–14
Eb/No Degradation At Site B
Parameter
Due To Fade At
B (dB)
Due To Fade At
A (dB)
CnC Ratio @ Site B
-5.3 -5.3
Uplink Fade @ Site B
3 -
Uplink Fade @ Site A
- 6
Faded CnC @ Site B -8.3 +0.7
Eb/No Degradation (dB) @ Site B
Per Figure D- QPSK
0.0 -0.1
D.10 Conclusion
There are several conclusions for operation with CnC:
• Operate adjacent carriers with sufficient spacing so there is no degradation.
• Adjust the modulation and code rate to alter the CnC ratio
• Change the modulation and code rate to scale the symbol rate
• Maximum CnC ratio is 7 dB with plenty of margin
• Maximum CnC ratio is 10 dB with some degradation
• Eb/No degradation is relatively tolerant to fades
• QPSK is least sensitive to adjacent carrier and CnC ratio followed by 8-PSK then
16-QAM.