CDM-Qx Satellite Modem

 

 

Revision 5

CnCPerformance Characterization

 

 

MN/CDMQx.IOM

 

 

 

 

 

 

Eb/No Degradation At Site B

 

 

 

Parameter

Due To Fade At

Due To Fade At

 

 

B (dB)

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

0.0

-0.1

 

 

Per Figure D- QPSK

 

 

 

 

 

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.

D–14

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Mocomtech CDM-QX operation manual Conclusion, Eb/No Degradation At Site B Parameter Due To Fade At