METHOD AND APPARATUS FOR PROCESSING CODED APERTURE RADAR (CAR) SIGNALS

摘要

A radar system in which Coded Aperture Radar processing is performed on received radar signals reflected by one or more objects in a field of view which reflect a transmitted signal which covers a field of view with K sweeps and each sweep including Q frequency changes. For Type II CAR, the transmitted signal also includes N modulated codes per frequency step. The received radar signals are modulated by a plurality of binary modulators the results of which are applied to a mixer. The output of the mixer, for one acquisition results in a set of Q·K (for Type I CAR) or Q·K·N (for Type II CAR) complex data samples, is distributed among a number of digital channels, each corresponding to a desired beam direction. For each channel, the complex digital samples are multiplied, sample by sample, by a complex signal mask that is different for each channel.

主权项

1. A method of processing radar signals reflected from one or more objects in a field of view of a radar transmitter transmitting the radar signals, the method comprising:
a. receiving and modulating the radar signals reflected from the one or more objects by plurality of binary phase shifters to produce a set of modulated signals, the binary phase shifters being controlled by binary coding data; b. summing the modulated signals and down converting them, preferably to base band, by a mixer producing in-phase and quadrature output signals which are each sampled and digitized by one or more A/D convertors to produce a set of real and imaginary digital values corresponding to the in-phase and quadrature output signals produced by the mixer during an acquisition of the field of view; c. distributing real and imaginary digital values corresponding to the in-phase and quadrature output signals produced by the mixer into a number of channels, the number of channels being equal to a number of desired radar beam directions to be processed concurrently and each channel having real and imaginary digital values corresponding to the digitized in-phase and quadrature signals output by the mixer; d. performing a complex multiplication using the real and imaginary digital values in each channel as one multiplicand and using real and imagery values of a signal mask as the other multiplicand, the signal mask being different for each channel and for each channel being selected to produce a desired beam with desired characteristics for each channel, each complex multiplication producing a multiplication result which has both real and imagery parts, the multiplication results or a summation of the multiplication results corresponding the acquisition of the field of view being at least conceptually organizable into a two dimensional set or matrix with each column of the set or matrix corresponding to frequency steps of the transmitted radar signal and each row of the matrix corresponding to a different sweep of the transmitted radar signal; e. transforming the real and imagery parts of said multiplication results or of a summation of said multiplication results in said set or matrix using a transformational function which produces transformed data, conceptually as a set or matrix, wherein each position of the set or matrix of the transformed data reflects the scattering strength of an object in said field of view at a corresponding range with a corresponding radial velocity, with each column of the matrix of transformed data representing range bins and each row of the transformed data representing velocity bins.