My PSM-4900 and PSM-2100 do not agree on the Eb/No parameter with Reed-Solomon codec installed?
The PSM-2100 was designed before Intelsat IESS 309 added the section defining how the Eb/No was measured with Reed-Solomon concatenated coding, and uses a different method. The method is encapsulated in ASIC and not changeable. Unfortunately the IESS lists two possible methods of computing the Eb/No with Reed-Solomon. The PSM-4900, being of more recent design, adheres to both IESS definitions by allowing the reference point to be varied. The two therefore may read differently, but actually achieve the same performance. Refer to Appendix RS for more information on setting the calculation parameter. If you think that the PSM-4900 modem’s performance is below that of any other commercial modem we would be very interested. In extensive testing we have found no other modem that can outperform the PSM-4900 in acquisition time, low Eb/No lock performance or BER vs. Eb/No performance.
