Analysis of a Detection Technique for a Spinning-Goniometer Direction-Finding System

Fourier analysis is used to show that the frequency spectrum of the output voltage of the linear detector of a spinning-goniometer direction-finding receiver varies as a function of time for a CW received signal. A filter for the second detector is considered having a bandwidth which varies with time in a similar way, thus effecting a ¿match¿ between the signal and the filter. A simple signal-to-noise ratio analysis shows that an improvement in signal-to-noise ratio is possible, compared to performance of a time-invariant system. The improvement is described by the equation I = 10 log10 T/T1, where T is the observation time and T1 is the basic period of the envelope of the input signal to the second detector produced by goniometer modulation.