STATISTICAL STUDY OF AN ACOUSTOOPTIC CORRELATOR IN TERMS OF ITS BANDWIDTH

An acousto-optic correlator (AOC) associated with pseudorandom sequenc es (PRS), as used in spread spectrum receivers, is considered. Simple expressions are derived for the output signal-to-noise ratio of an AOC in two cases: when the frequency response H(f) of the correlator is e qual to rect(f/Delta f) or equal to sinc(pi f/Delta f), where rect(x) is the rectangle function, sinc(x) = sinx/x and Delta f is the correla tor bandwidth. These simple expressions are given in terms of the rati o alpha of the code bit rate F-c of the PRS to the bandwidth Delta f o f the AOC. It will be shown that when H(f)= rect(f/Delta f) and alpha is greater than 2, a loss results in the output signal-to-noise ratio approximately equal to 1/alpha with respect to an ideal (infinite band width) AOC. When H(f) = sinc(pi f/Delta f) the loss equals 1.5/alpha. (C) 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-32 86(98)03703-9].