## Answer 6.10

#### A microwave radio link implies that this must be a bandpass channel.
The Shannon-Hartley equation gives us the required relationship between channel capacity in bits/second, the bandwidth and the signal to noise ratio as follows:
Channel capacity C = B log2(S / N + 1) bits/second
Therefore C = 400 · 103log2(1000 + 1) bits/second = 3.987 Mbps
Hence the channel can support an error free bit rate of 2 Mbps.
The number of symbol states required for a bandpass channel with a bit rate of 2 Mbps is given by:
Mbandpass = 2C/B = 32 symbol states.
(Note: Mbaseband = 2C/2B.)