Short pulse/stepped frequency radar system

• US 20050270219A1
• Filed: 06/08/2004
• Published: 12/08/2005
• Est. Priority Date: 06/08/2004
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Dwelly, Wesley H., Adams, Vinh N.
• Granted Patent: US 7,142,153 B2
• Time in Patent Office: Days
• US Class Current: 342/22
• 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 13/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated

Abstract

A unique hardware architecture that combines short pulse, stepped frequency and centerline processing. The inventive architecture implements a radar system having a transmitter for transmitting short pulses, each pulse being stepped in frequency and a receiver receiving the pulses and providing an output signal in response thereto. In the illustrative embodiment, the transmitter includes a frequency source, an RF switch coupled to the source and a controller for controlling the RF switch. The receiver includes a signal processor implemented with a center line roughing filter. The signal processor has multiple channels each of which has a range gate and a digital filter. The digital filter includes a Fast Fourier Transform adapted to output a range Doppler matrix.

Claims

1. A radar system comprising:

first means for transmitting a train of short pulses, each pulse being stepped in frequency and

second means for receiving said pulses and providing an output signal in response thereto, said second means including means for sampling said train of pulses at a centerline thereof.

2. The invention of claim 1 wherein said first means outputs pulses less than or equal to 1 nanosecond in rise or fall time.

3. The invention of claim 1 wherein said first means includes a frequency source.

4. The invention of claim 3 wherein said first means further includes an RF switch coupled to said frequency source.

5. The invention of claim 4 wherein said first means further includes a controller for controlling said RF switch.

6. The invention of claim 5 wherein said controller activates said switch to switch between 3 and 20 nanosecond RF pulses.

7. The invention of claim 1 wherein said second means includes a signal processor.

8. The invention of claim 7 wherein said signal processor includes a filter.

9. The invention of claim 8 wherein said signal processor includes a range gate.

10. The invention of claim 7 wherein said second means includes a digital filter.

11. The invention of claim 10 wherein said digital filter includes a Fast Fourier Transform.

12. The invention of claim 11 wherein said Fast Fourier Transform is adapted to output a range Doppler matrix.

13. A radar system comprising:

a transmitter adapted to transmit pulses less than or equal to 1 nanosecond in rise or fall time, each pulse being stepped in frequency and

a receiver for receiving said pulses and providing an output signal in response thereto, said receiver including a signal processor with a filter adapted to operate on an analog range gate applied to said pulses.

14. A method for sensing through walls including the steps of:

transmitting a train of short pulses of electromagnetic energy, each pulse being stepped in frequency and

receiving said pulses and providing an output signal in response thereto, said step of receiving further including the step of sampling said train at a centerline thereof.

15. A radar system comprising:

first means for receiving a train of pulses, each pulse being stepped in frequency;

second means for filtering said train to pass a center spectral line thereof; and

third means for sampling said filtered pulse train and providing an output in response thereto.

16. The invention of claim 15 further including means for digitizing the output of said third means.

17. The invention of claim 15 wherein each of said pulses is less than or equal to 1 nanosecond in rise or fall time.

18. The invention of claim 15 wherein said second means includes means for filtering said pulses within an analog range gate.

25. The invention of claim 15 wherein said line is centered at an intermediate frequency of at least one of said pulses.

26. The invention of claim 25 wherein said second means includes means for passing signals within a pass band equal to twice a width of said at least one pulse.

19. A method including the steps of:

receiving a train of pulses, each pulse being stepped in frequency;

filtering said train to pass a center spectral line thereof, and

sampling said filtered pulse train and providing an output in response thereto.

20. The invention of claim 19 further including the step of digitizing said sampled filtered pulse train.

21. The invention of claim 19 wherein each of said pulses is less than or equal to 1 nanosecond in rise or fall time.

22. The invention of claim 19 wherein said filtering step further includes the step of filtering said pulses within an analog range gate.

23. The invention of claim 19 wherein said line is centered at an intermediate frequency of at least one of said pulses.

24. The invention of claim 23 wherein said filtering step includes the step of passing signals within a passband equal to twice a width of said at least one pulse.