Recovery of symbols from noise (cont)

The chances of the receiver making the correct decision are of course greatly improved if the detector incorporates some form of 'averaging' (filtering) in order to improve the signal to noise ratio at a particular sampling point.

For example, passing the symbol through an integrator would gradually improve the S/N ratio, reaching a maximum at the end of the symbol period. If the integrator continued to average over the following symbol (in this case a zero), the output would begin to fall and would yield a non-optimum result for both the 1 and 0 symbols. For this reason it would be prudent to reset the integrator at the beginning of each new symbol. This type of detector is commonly described as an integrate and dump filter.