US 7,952,515 B2 · Range gated holographic radar

Abstract

Narrow virtual transmit pulses are synthesized by differencing long-duration, staggered pulse repetition interval (PRI) transmit pulses. PRI is staggered at an intermediate frequency IF. Echoes from virtual pulses form IF-modulated interference patterns with a reference wave. Samples of interference patterns are IF-filtered to produce high spatial resolution holographic data. PRI stagger can be very small, e.g., 1-ns, to produce a 1-ns virtual pulse from very long, staggered transmit pulses. Occupied Bandwidth (OBW) can be less than 10 MHz due to long RF pulses needed for holography, while spatial resolution can be very high, corresponding to ultra-wideband (UWB) operation, due to short virtual pulses. X-Y antenna scanning can produce range-gated surface holograms from quadrature data. Multiple range gates can produce stacked-in-range holograms. Motion and vibration can be detected by changes in interference patterns within a range-gated zone.

Claims11

Dependent claims

A range-gated holographic radar, comprising:

a PRI generator for producing PRI pulses;
an intermediate frequency IF generator for producing an IF modulation signal;
a stagger modulator responsive to the PRI pulses and to the IF modulation signal for producing staggered PRI pulses;
a first pulse generator responsive to the staggered PRI pulses for generating transmit pulses having a duration longer than the longest transmit pulse to desired echo duration;
an RF oscillator responsive to the transmit pulses for producing transmit RF bursts and for forming reference waves;
an antenna connected to the RF oscillator for radiating the transmit RF bursts and for receiving echoes from the bursts;
a range delay element connected to the PRI generator for producing range delay pulses;
a second pulse generator responsive to the range delay pulses for generating gate pulses;
an RF magnitude sampler responsive to the gate pulses and connected to the antenna for producing RF magnitude samples of the sum of the reference waves and echoes;
an IF bandpass filter for passing IF modulated magnitude samples;
and
an IF detector for demodulating the filtered magnitude samples and for producing an interferometric output signal.

9 more elements

Dependencies are inferred from the claim text.

Range gated holographic radar

Life of this patent

Range gated holographic radar

Life of this patent

Abstract

Claims11