The document discusses different digital signal reception techniques, including optimal coherent reception of FSK, non-coherent detection of FSK, DPSK reception, and QPSK reception. It notes that optimal detection involves observing the received signal for one symbol duration and guessing the symbol using maximum likelihood decision rules, and that coherent detection assumes the receiver has exact replicas of transmitted signals while dealing with additive Gaussian noise.

1. OPTIMAL RECEPTION OF
DIGITAL SIGNALS

2. Optimal coherent reception of
FSK

5. Non coherent detection of FSK

7. DPSK reception

10. QPSK reception

11. • A correlation receiver for QPSK

15. summary
• To perform detection the receiver observes the received
signal for the duration of one symbol and guesses which
particular symbol was sent according to some set of rules.
• In coherent detection the receiver is assumed to be in
possession of exact replicas of the transmitted signals.
• In coherent detection a source of error in decision making
process is additive thermal noise at the receiver
input ,which is modelled as Gaussian noise of zero mean
and constant power spectral density.

16. • When all the signals are transmitted with equal
probability ,the optimum rule turns out to be maximum
likelihood; the criterion for optimality is minimization of
the average probability of symbol error.
• The optimum filters is implemented in the form of a bank of
correlators or matched filters followed but maximum
likelihood detectors.
• In non-coherent detection the receiver has no knowledge of
carrier phase. The presence of phase uncertainty in received
signal is the source of error .