AN INVESTIGATION OF DITIGAL TECHNIQUES FOR OBTAINING CORRELATION ENVELOPES.
Abstract
A problem considered was that of obtaining the envelope of the output of a clipped input digital correlator, an input consisting of a deterministic, hard-limited signal, buried in Gaussian noise. The problem arises from the fact that sampling the input is initiated at some random input phase angle, thus causing the output to be down from its theoretical peak value. The correlator employs a type of sampling commonly used with bandpass signals, a sampling of the signal and its quadrature. With this type of sampling, two outputs, after summing, should produce the envelope peak, independent of the input phase. This was tried experimentally with the following results: (1) The sin square x detection procedure does give the correlation envelope peak, for infinite signal-to-noise ratio, independent of phase shift between input signal and reference. (2) For finite signal-to-noise ratios from -5 dB to +5 dB, the detection procedure gives the mean envelope peak with a periodic variation as the input phase shift is varied from 0 to -90 degrees. The variation, 8% of full scale, is due to the chosen ratio of carrier frequency to sampling frequency. (3) The correlation envelope lies between erf the square root of (S/2N) and (S/N) divided by (1 + S/N), where S/N is the signal-to-noise ratio. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 05, 1970
- Accession Number
- AD0707801
Entities
People
- J. H. Beebe
Organizations
- Pennsylvania State University