[linux-dvb] symbol rate and signal level
awalls at radix.net
Wed Jun 11 13:03:28 CEST 2008
On Tue, 2008-06-10 at 23:24 -0700, alireza ghahremanian wrote:
> Dear friends
> What is the relation between symbol rate and signal level, why when decrease the symbol rate the signal level increase ?
S/N = Es/No * Rs/B
S = Received signal power (Watts)
N = Noise power (Watts)
Es = Average energy per symbol (Joules/symbol)
No = Noise density (Watts/Hz)
Rs = Symbol rate (Symbols/second)
B = Bandwidth (Hz)
For a particular BER, the receiver will require a certain Es/No. If S
goes down, then Rs must go down (or B must go up) as well to maintain
the same Es/No and hence the same BER.
So in the case of lowering Rs and holding S/N the same, you are
operating at a higher Es/No which means a lower BER.
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