Matched-filter SNR boosts performance

Some misconceptions regarding matched filtering and signal-to-noise enhancement or optimization have arisen. Such developments can often be traced to a lack of precision in defining terms. The present article attempts to remedy the situation by providing a definition for a matched filter. Such a filter is defined as a network which enhances or maximizes the output signal-to-noise ratio (SNR) of a spread-spectrum system by shaping the received waveform. The output of the filter is the result of the convolution of the received waveform and the impulse response of the matched filter. Attention is given to transversal matched filters in which the received waveform and the impulse response are identical. Two solid-state technologies help make certain types of matched filters easier to construct and more practical to use, taking into account surface-acoustic wave devices, and charge transfer devices (CTD).