Communication channel: baud rate, bit rate, etc.
Quote:
The communication channel (ideally) "lets through" frequencies from 450 Hz to 3250 Hz and has a signal / noise (S/N) ratio of 42 dB.
(a) How many
signal elements per second (bauds) is it possible to transfer over this channel?
(b) What is the
max. bit rate over this channel?
(c) How do results from
(a) and
(b) influence
modem's properties?
Please, help me correct my "answers". Thank you.
(a) 
? Reasoning: you only get 1 crest and 1 trough, hence this theoretical limit? So, if my reasoning is sound, the baud rate =5600\text{ Bd})
(b) Depends on number of states each baud (signal) can have. E.g. if a signal can be in 4 states, then each baud "carries" 2 bits, and the max. bit rate = 2 * baud rate.
As we're given the S/N ratio, we can use the equation for the channel capacity: }_\textrm{the definition of dB?}\stackrel{?}{=} (3250\text{ Hz}-450\text{ Hz})*42\text{ dB})
(c) We divide the max. bit rate from (b) by the baud rate from (a) and get the number of bits/baud? That's all? (Wondering)
PS: I see that, instead of repairing the [tex] tag, you've just added the [TEX]. (Rofl)
Re: Communication channel: baud rate, bit rate, etc.
The equation for channel capacity of a band limited channel with bandwidth W is )
where 
is SNR. But this SNR is not in dB. So substitute 10^4.2 for in the equation to get the maximum bit rate.
Re: Communication channel: baud rate, bit rate, etc.
Is answer to (a) correct?
And what would you add to my (incomplete) answer to (c):
For (b), I got the max. bit rate of 
. So, given the theoretical limit of 
from (a), what is the answer to (c)? Is it, that (if we ever wanted to achieve theoretical throughput) the signals should have 
possible states and we would hence have 
?
