Ultra wideband radar signal processor for electronically scanned arrays

• US 5,351,053 A
• Filed: 07/30/1993
• Issued: 09/27/1994
• Est. Priority Date: 07/30/1993
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Wicks, Michael C., Brown, Russell D.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/100,649
• Time in Patent Office: 424 Days
• Field of Search: 342/158, 342/368, 342/371, 342/372, 342/73, 342/74, 342/81, 342/99, 342/132, 342/139, 342/140, 342/202
• US Class Current: 342/158
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/282 using a frequency modulated carrier wave G01S13/286 takes precedence
• CPC Class Codes: G01S 13/426 Scanning radar, e.g. 3D radar G01S13/66 takes precedence
• CPC Class Codes: H01Q 3/22 varying the orientation in accordance with variation of frequency of radiated wave
• CPC Class Codes: H01Q 3/42 using frequency-mixing H01Q3/2676 takes precedence

Abstract

A radar system that includes an ultra wideband radar signal processor for electronically scanned arrays that utilizes frequency offset generation (FOG) to achieve beam steering as compared with phase shift and time delay techniques of conventional radars. The device comprises a transmit antenna, a chirp generator connected to the transmit antenna and a first summing circuit, a receiver antenna connected to the first summing circuit, a Doppler de-ramping chirp circuit connected to a second summing circuit, the output of the second summing circuit connected to an amplitude and weighting circuit and the output of the amplitude circuit connected to a spectrum analyzer of a Fast Fourier Transform (FFT) circuit. The signal processing consists of mixing the target returns with the transmitted signal to obtain a video beat note signal. This video beat note signal is mixed with a Doppler de-ramping chirp waveform which is matched to the desired target velocity. The output is amplitude weighted and the FFT algorithm applied. To achieve beam steering for the detection of off boresight targets, a phased array with distributed receivers is required. Also, frequency offset generation must be incorporated into the Doppler de-ramping chirp generator.

Claims

1. An ultra-wideband radar tracking system for tracking a moving target, said ultra-wideband radar tracking system comprising:

a multi-octave signal generator which generates an ultra-wideband chirped pulse signal, said ultra-wideband chirped pulse signal comprising a signal which is at least an octave in bandwidth;

a phased array antenna which is electrically connected with said multi-octave signal generator, said phased array antenna receiving said ultra-wideband chirped pulse signal from said multi-octave signal generator, and transmitting it into space, said phased array antenna having a plurality of radiating antenna elements;

a means for processing signals which is electrically connected to said phased array antenna, said signal processing means using frequency offset generation to electronically steer the ultra-wideband chirped pulse signal emitted by said phased array antenna, said signal processing means providing a frequency offset between said radiating antenna elements for said ultra-wideband chirped pulse signal to electrically steer the ultra-wideband chirped pulse signal by frequency offset mixing.

2. An ultra-wideband radar tracking system for tracking a moving target, said ultra-wideband radar tracking system comprising:

a multi-octave signal generator which generates an ultra-wideband chirped pulse signal, said ultra-wideband chirped pulse signal comprising a signal which is at least an octave in bandwidth;

a phased array antenna which is electrically connected with said multi-octave signal generator, said phased array antenna receiving said ultra-wideband chirped pulse signal from said multi-octave signal generator, and transmitting it into space, said phased array antenna having a plurality of radiating antenna elements which receives a doppler shifted chirped pulse signal from said moving target;

a means for producing a baseband signal with a video beat note, said producing means being electrically connected with said multi-octave signal generator in order to receive and mix said ultra-wideband chirped pulse signal with said doppler shifted chirped pulse signal;

a means for generating a plurality Doppler deramping chirp signals which when mixed with said baseband signal, provides an individual frequency offset for each of the antenna elements in the phased array antenna; and

a means for mixing said baseband signal with each of said plurality of Doppler deramping chirp signals to produce thereby a plurality of frequency-steered signals which collectively represent said ultra-wideband chirped pulse signal with said frequency offset included therein.

3. An ultra-wideband radar tracking system for tracking a moving target, said ultra-wideband radar tracking system comprising:

a multi-octave signal generator which generates an ultra-wideband chirped pulse signal;

a phased array transmitting antenna which is electrically connected with said multi-octave signal generator, said phased array transmitting antenna receiving said ultra-wideband chirped pulse signal from said multi-octave signal generator, and transmitting it into space, said phased array transmitting antenna having a plurality of radiating antenna elements;

a receiving antenna for receiving a Doppler-shifted chirped pulse as said target-echo return signal is reflected from said moving target, said receiving antenna outputting said Doppler-shifted chirped pulse; and

a means for processing signals which is electrically connected to said receiving antenna, said signal processing means using frequency offset generation to electronically steer the ultra-wideband chirped pulse signal emitted by said phased array transmitting antenna.

4. An ultra-wideband radar tracking system for tracking a moving target, said ultra-wideband radar tracking system comprising:

a multi-octave signal generator which generates an ultra-wideband chirped pulse signal, said ultra-wideband chirped pulse comprising a signal which is at least an octave in bandwidth;

a phased array transmitting antenna which is electrically connected with said multi-octave signal generator, said phased array transmitting antenna receiving said ultra-wideband chirped pulse signal from said multi-octave signal generator, and transmitting it into space, said phased array transmitting antenna having a plurality of radiating antenna elements;

a receiving antenna for receiving a Doppler-shifted chirped pulse as said target-echo return signal is reflected from said moving target, said receiving antenna outputting said Dopplar-shifted chirped pulse;

a means for producing a baseband signal with a video beat note, said producing means being electrically connected with said multi-octave signal generator in order to receive and mix said ultra-wideband chirped pulse signal with said Doppler-shifted chirped pulse;

a means for generating a plurality Doppler deramping chirp signals which when mixed with said baseband signal, provides an individual frequency offset for each of the antenna elements in the phased array transmitting antenna; and

a means for mixing said baseband signal with each of said plurality of Doppler deramping chirp signals to produce thereby a plurality of frequency-steered signals which collectively represent said ultra-wideband chirped pulse signal with said frequency offset included therein.