Radar system and method using pulse compression

• US 7,889,118 B1
• Filed: 09/22/2008
• Issued: 02/15/2011
• Est. Priority Date: 09/22/2008
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Finley, Jeffery A., Woodell, Daniel L.
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US12/235,411
• Time in Patent Office: 876 Days
• Field of Search: 342/26.B
• US Class Current: 342/118
• CPC Class Codes: G01S 13/28 with time compression of received pulses
• CPC Class Codes: G01S 13/935 for terrain-avoidance
• CPC Class Codes: G01S 13/953 mounted on aircraft
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

A radar system includes an antenna and has short range detection capability. The radar system includes a receiver coupled to the antenna for receiving a receive signal associated with a pulse compressed transmission signal and a matched filter configured to accumulate at least a portion of the receive signal for a particular range. The portion of the receive signal is associated with a corresponding portion of the pulse compressed transmission signal.

Claims

1. A radar system including an antenna, the radar system having short range detection capability, the radar system comprising:

a receiver coupled to the antenna for receiving a receive signal associated with a pulse compressed transmission signal;

a first matched filter configured to accumulate at least a portion of the receive signal for a particular range, the portion of the receive signal corresponding to less than a full pulse width of the pulse compressed transmission signal, wherein the matched filter is implemented using a first pulse decompression algorithm executed by a processor; and

a full matched filter corresponding to the full pulse width of the pulse compressed transmission signal, wherein the first matched filter is applied to the receive signal at a time less than twice the pulse width after the pulse compressed transmission signal is provided and the full matched filter is applied to the received signal at a time longer than twice the pulse width after the pulse compressed transmission signal is provided.

2. The radar system of claim 1, wherein the first matched filter is part of a set of first matched filters including four filters using four decompression algorithms corresponding to four equal portions of the pulse compressed transmission signal.

3. The radar system of claim 2, wherein the pulse compressed transmission signal changes from a lower frequency to a higher frequency and the first matched filter is part of a set of filters using pulse decompression algorithms.

4. The radar system of claim 1, further comprising:

a processor for determining a presence of a target at close range in response to data associated with the portion of the receive signal.

5. The radar system of claim 1, further comprising power compensation algorithms for uniform power distribution over a plurality of ranges.

6. The radar system of claim 1, wherein the first matched filter is designed to accumulate the receive signal associated with the last one half of the transmit pulse.

7. The radar system of claim 1 wherein the pulse compression signal has a width of between 1 and 100 microseconds.

8. The radar system of claim 1 wherein the portion of the receive signal is associated with the last half of the pulse compressed transmission signal.

9. An aircraft radar system for receiving a receive signal associated with a pulse compressed transmission signal, the aircraft radar system comprising:

a processor for determining a presence of a target in response to data, the processor accumulating at least a portion of the receive signal using a first matched filter configured for a particular range to provide the data, the portion of the receive signal being associated with a corresponding portion of the pulse compressed transmission signal, wherein the first matched filter is implemented using a first pulse decompression algorithm executed by the processor, wherein the processor is further configured to accumulate the received signal using a full matched filter corresponding to an entire pulse width of the received signal after a full pulse width reception period, the full matched filter being implemented using a second pulse decompression algorithm executed by the processor.

10. The aircraft radar system of claim 9, wherein the first matched filter is part of a series of matched filters, wherein each filter in the series is configured for particular range distances of the pulse compressed transmission signal.

11. The aircraft radar system of claim 10, wherein the matched filters accumulate respective portions of the receive signal, the respective portions being associated with particular respective portions of the pulse compressed transmission signal.

12. The aircraft radar system of claim 9, wherein the aircraft radar system is a weather radar system for use with a display, wherein the processor causes the display to display indications of the targets.

13. The aircraft radar system of claim 12 wherein the targets are terrain targets, weather targets, obstacles, or other airborne objects.

14. The aircraft radar system of claim 9, wherein the pulse compressed transmission signal is a long pulse signal having a width of at least 100 microseconds.

15. The aircraft radar system of claim 9, wherein the pulse compressed transmission signal has a length of between 1 and 100 microseconds and the target is within 0.5 nautical miles.

16. The aircraft radar system of claim 9, wherein the processor matches the modulation of the received signal with a known modulation associated with the pulse compressed transmission signal to determine a range to the target.

17. A weather radar system for detecting a target by providing a radar pulse having a pulse width and receiving a return, the weather radar system comprising:

means for accumulating portions of the return associated with portions of the radar pulse from different ranges after the radar pulse ends and before a pulse width reception period is completed, the means for accumulating including a set of matched filters;

means for accumulating a full return, the means for accumulating the full return including a full matched filter, wherein the full matched filter is applied after the pulse width reception period is completed, wherein the pulse width reception period has a length of the pulse width; and

means for detecting a presence of the target at the distance less than the pulse width multiplied by the speed of the pulse using data associated with the portions of the return from the set of matched filters and detecting a presence of the target at the distance more than the pulse width multiplied by the speed of the pulse using data from the full matched filter associated with the full return.

18. The radar system of claim 17, wherein the set of matched filters includes a set of pulse decompression algorithms.

19. The radar system of claim 18, wherein the means for detecting matches modulation associated with the pulse to modulation on the return.

20. The aircraft radar system of claim 17, wherein the pulse is a long pulse signal having a width of at least 100 microseconds.