Clutter removal by polynomial compensation

A radar receiver arranged to receive a received signal, the received signal comprising components in a desired target Doppler frequency band and components in a clutter Doppler frequency band, comprising:

• (a) sampling means, fed by the received signal and operating at a predetermined sampling rate, the sampling rate sufficient to validly sample the components in the clutter band but less than a rate sufficient to validly sample a lowest frequency in the desired target band, for periodically generating a set of selected samples;
• (b) signal generator means, connected to receive the set of selected samples, for generating a clutter estimate signal substantially equal to the values of a polynomial fit through the set of selected samples;
• and
• (c) comparing means, connected to receive the received signal and the clutter estimate signal, for providing an estimate of the received signal components in the desired target Doppler frequency range.

A method for removing undesired components in a clutter Doppler frequency band from a received signal received by a radar receiver, the received signal comprising components in the clutter Doppler frequency band and components in a desired target Doppler frequency band, comprising the steps of:

• (a) sampling the received signal at a predetermined sampling rate to periodically provide a set of selected samples, the sampling rate sufficient to cause the components in the clutter frequency band to be validly sampled and the components in the desired target frequency band to be distributed into the clutter frequency band;
• (b) generating a clutter estimate signal from each set of selected samples, the clutter estimate signal substantially equal to the values of a polynomial fit through the selected samples;
• and
• (c) subtracting the received signal and the clutter estimate signal, to periodically provide an output signal indicative of the components of the echo signal in the desired target Doppler frequency range.