Paradise P300 specifications RS Code Rate

	Eb		EDec	10 log		(RS Code Rate	(	k	))
	N0		N0 &		10			n
		'
It is this Eb / No that is typically displayed on the front panel of Modem equipment.

Finally, after the RS Decoder comes Deframing and baseband processing'such as Drop/Insert. IBS/SMS or IDR deframing does decrease the bandwidth, but the bandwidth reduction effects of deframing are ignored as INTELSAT chose to define the mandatory modem performance in terms of Eb / No, specifying that this relates to the Composite Information Bit Rate (ie it includes framing). Baseband processing has no effect on bandwidth and is totally ignored.

8.12.3Practical Implications of Displayed Eb/No Practically this means the following:

For a constant Tx Power, you will get the same displayed Eb / N o whatever the settings of Modulation Inner FEC, and Outer (RS) FEC, as the Eb / No display compensates for these parameters. The bandwidth will vary and so will the Carrier / Noise at the input of the demod, but the displayed Eb / No will be steady as it compensates for these parameter changes.

When comparing BER performance for different Modulation / FEC schemes against Eb / No, the

plotted Eb / No already accounts for the changes in Carrier / Noise caused by the different Modulation

and FEC settings. Any BER difference you see with different schemes is a real difference, you don’t have to further compensate for the changes in Carrier / Noise this change induces.

You do however have to be aware of Bandwidth considerations. You might find a Modulation / FEC scheme which gives an exceptional BER for a given Eb / No, but it will of little practical value if the bandwidth it requires occupies a whole transponder.

When you look at BER performance figures at a specified Eb / N o you get the same BER performance whether the data is framed or not. Adding framing to a Closed Network link would increase the bandwidth, decrease the Carrier / Noise, decrease the displayed Eb / No (as it does not compensate for framing) and therefore degrade the BER. However when brought back to the same Eb / No you do of course recover the same BER. Framing therefore does not degrade the BER for a stated Eb / No, but it does require more power (and bandwidth) to achieve the same Eb / No.

P300H P300 Series Modem Installation and Operating Handbook Page 160