US 5,309,161 A · Radar with doppler tolerant range sidelobe suppression and time domain signal processing

Abstract

A radar system includes a doppler/pulse compressor/range sidelobe suppressor filter bank (40), which separates received echo signals according to their frequency spectrum into doppler channels, and within each doppler channel performs pulse compression for reducing the duration of the received signals, and also performs range sidelobe suppression, for improving range resolution. It may be advantageous to perform certain types of processing in the time domain, such as determination of spectral moments for estimating velocity spread, mean closing velocity, and reflectivity of a diffuse target such as a weather phenomenon. An inverse (frequency-to-time) transform (50) is performed on the signals produced by the doppler/pulse compressor/range sidelobe suppressor filter bank (40), to produce a reconstructed version of the received signals. In these reconstructed signals, the pulses are compressed, and range sidelobes are reduced. The time-domain processing (62) is performed on the reconstructed signals. In a particular embodiment of the invention, the range sidelobe suppression and pulse compression filters (34a, 34b . . . ) follow the doppler filters (32), but any ordering of the filters may be used. Interchannel frequency interference attributable to the non-zero bandwidth of the Doppler filters may be reduced by pulse-to-pulse time weighting (30) applied to the received signals over a time window corresponding to a particular dwell, together with inverse weighting (62) following the inverse transformation.

Claims11

Dependent claims

A ranging system for transmitting dispersed signals through a medium toward a target, and for receiving echoes of said signals, comprising:

transmitting means for transmitting dispersed signal pulses, having a predetermined duration, toward said target;
receiving means for receiving echo signals from said target for forming received pulse signals;
a bank of a first plurality of pulse-to-pulse doppler filter channels;
a plurality, equal to said first plurality, of pulse compression means;
a plurality, equal to said first plurality, of range sidelobe suppression means;
coupling means coupled to said receiving means, said bank of pulse-to-pulse doppler filter channels, said pulse compression means, and said range sidelobe suppression means, for coupling each of said pulse compression means in cascade with one of said range sidelobe suppression means and with one of said doppler filter channels, to form a plurality, equal to said first plurality, of cascaded filters, and for connecting each of said cascaded filters to said receiving means, for filtering said received signals to form a plurality, equal to said first plurality, of doppler filtered, frequency domain received signals in which range sidelobes are suppressed and in which the effective duration of said pulses is shortened from said predetermined duration;
pulse-to-pulse frequency-to-time signal transformation means coupled to each of said cascaded filters, for converting said frequency domain received signals into regenerated time-domain received signals in which said range sidelobes are suppressed and in which the effective duration of said pulse is shortened from said predetermined duration.

4 more elements

A method for determining the range of a target, comprising the steps of:

generating dispersed signal pulses having a predetermined duration;
transmitting said dispersed signal pulses toward said target for generating echo signals;
receiving said echo signals from said target for forming received pulse signals;
applying said received pulse signals to a plurality of pulse-to-pulse filter channels;
pulse-to-pulse doppler filtering said received pulse signals within said plurality of pulse-to-pulse filter channels;
time-compressing said received filter channels within said pulse-to-pulse filter channels;
suppressing range sidelobes of said received pulse signals within said pulse-to-pulse filter channels, whereby a plurality of doppler-filtered received pulse signals are generated, in which said pulses have a duration less than said predetermined duration, and in which range sidelobes are suppressed;
applying said plurality of doppler-filtered received pulse signals from said plurality of channels to a corresponding input port of a pulse-to-pulse frequency-to-time transformation filter, and within said pulse-to-pulse frequency-to-time transformation filter, processing said doppler-filtered received pulse signals together to regenerate said received pulse signals in the form of compressed pulse echoes, having a duration less than said predetermined duration, and in which range sidelobes are suppressed.

5 more elements

Dependencies are inferred from the claim text.

Radar with doppler tolerant range sidelobe suppression and time domain signal processing

Life of this patent

Radar with doppler tolerant range sidelobe suppression and time domain signal processing

Life of this patent

Abstract

Claims11