Abstract. A compression algorithm
for polyphase radar signals that have an area of zero sidelobes in the vicinity
of the central peak of the aperiodic autocorrelation function has been
considered. These signals, which are called polyphase (p-phase, where p
is a prime number) coherent complemented signals, are a burst of p
coherent phase-code-manipulated pulses coded by an ensemble of p-pair D-codes.
The zero sidelobe area of the autocorrelation function of the polyphase
coherent complemented signals permits reducing the threshold of detection of
radar targets to the noise level, thus increasing the detection probability.
Also, by virtue of the large base, these signals have high compression
coefficients, which makes it possible to solve the problem of discerning
targets that are closely located in space to each other and have close radial
velocities as well as measuring their coordinates with high precision. The
polyphase phase-code-manipulated probing signals permit significantly enhancing
the secrecy of the radiolocation stations’ operation.
The device for compression
of the polyphase coherent complemented signals consists of an input register
with N cells, a discrete transform processor called a discrete
D-transformation processor, with N inputs and N outputs, (p-1)
identical shift registers with QN
cells and (p-1) identical adders of complex numbers, where N
is the length of the D-code and Q is the parameter inverse to the
duty ratio. It is shown that the matrix of complementary sequences is the
product of the matrix of Vilenkin–Chrestenson functions and a diagonal one with
elements from the first row of the matrix of complementary sequences. Thus, the
algorithm of the discrete D-transformation processor’s operation is an
algorithm of fast Fourier transform in the basis of the Vilenkin–Chrestenson
functions with addition of weighing coefficients at the processor’s input, which
are the first row of the matrix of complementary sequences. The reports of the
discrete D-transform spectrum for computing the autocorrelation function are
taken from the processor’s outputs in conformity with arrangement of one of the
N/p
ensembles of the p-pair
complementary sequences. Thus, we can obtain
N/p
various autocorrelation
functions.
The considered compression
algorithm for the polyphase coherent complemented signals makes it possible to
achieve effective real-time solutions of the problems of discerning and
measuring the coordinates of grouped targets of the radar that have close
radial velocities.
Keywords: burst of pulses, polyphase
signal, complementary sequence, autocorrelation function, sidelobes, detection
threshold, radial velocity, matched filter, system of Vilenkin–Chrestenson
functions, fast Fourier transform, signal graph, weighing coefficient.
References
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Ipanov
R.N. Polyphase
coherent complemented signals. Zhurnal Radioelektroniki -
Journal of Radio Electronics, 2017, No. 1. Available at
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Trahtman
A.M., Trahtman V.A. Osnovy teorii diskretnyh signalov na konechnyh
intervalah. [Undamentals of the theory of discrete signals on finite
intervals]. Moscow, Sov. Radio Publ, 1975, 208 p. (In Russian).
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Ipanov
R.N. Compression algorithm of coherent complemented signals. Zhurnal Radioelektroniki - Journal of Radio Electronics, 2016, No. 9. Available
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http://jre.cplire.ru/jre/sep16/9/text.pdf. (In Russian).