CDM-Qx Satellite Modem

Revision 5

Forward Error Correction Options

MN/CDMQx.IOM

It can be seen that the 8-PSK Rate 3/4 Turbo performance closely approaches that of the Rate 2/3 TCM/Reed-Solomon case – the BER performance is within approximately 0.4 dB. However, it should be noted that the Rate 3/4 Turbo mode is 20% more bandwidth efficient than the TCM case. The additional advantages of Turbo (lower delay, performance during fades etc) should also be considered.

Table 6-6. Turbo Product Coding Summary

FOR

AGAINST

Exceptionally good BER performance - significant improvement compared

Nothing!

with every other FEC method in use today

 

No pronounced threshold effect - fails gracefully

 

 

 

Exceptional bandwidth efficiency

 

 

 

Coding gain independent of data rate (in this implementation)

 

 

 

Low decoding delay

 

 

 

Easy field upgrade in Modem

 

 

 

6–9

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Mocomtech CDM-QX operation manual Turbo Product Coding Summary, For Against