Linear frequency coded sequence (L.F.C.S.)

Abstract

This paper discusses the ambiguity functions of linear frequency coded sequences, i.e. codes whose phase progression follows a law which is quadratic or approximately so. The ambiguity function is studied via two approaches: the first, theoretical, approach uses the general theory of the ambiguity function and the special case of the discrete ambiguity function (d.a.f.) of number sequences; the second approach uses plots of digitally computed autocorrelation functions and ambiguity diagrams to validate the theory. If the linear frequency coded sequence is regarded as being generated by sampling of a linear f.m. waveform, then an ideal autocorrelation function can only be produced by sampling at a rate approximately equal to the signal's bandwidth.