Radar system utilizing chaotic coding

• US 5,321,409 A
• Filed: 06/28/1993
• Issued: 06/14/1994
• Est. Priority Date: 06/28/1993
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Missile Systems Company
• Inventors: Walker, W. T.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/085,995
• Time in Patent Office: 351 Days
• Field of Search: 342/21, 342/132, 342/134, 342/135, 342/145, 342/202, 342/201, 342/204
• US Class Current: 342/202
• CPC Class Codes: G01S 13/288 phase modulated

Abstract

A radar system (20) has a chaotic code source (22) with a chaotic code output (23), which generates a chaotic code according to a chaotic difference equation. The radar system (20) further includes a transmitter (24) with a carrier signal source (28) of a carrier signal (29), and an encoder (30) having as a first input the carrier signal (29) of the carrier signal source (28) and as a second input the chaotic code output (23) of the chaotic code source (22), and as an output a transmitted radar signal (36) having the chaotic code output (23) encoded onto the carrier signal (29). A radar system receiver (26) includes a correlator (46) having as a first input the chaotic code output (23) of the chaotic code source (22) and as a second input a received radar signal (44), and as an output an indication of the correlation of the first and second inputs. The correlation is used to determine the distance, speed, or other characteristic of an object that reflected the radar signal.

Claims

1. A radar system, comprising:

a chaotic code source having a chaotic code output;

a transmitter including

a carrier signal source of a carrier signal, and

an encoder having as a first input the carrier signal of the carrier signal source and as a second input the chaotic code output of the chaotic code source, and as an output a transmitted radar signal having the chaotic code output encoded onto the carrier signal; and

a receiver including

a correlator having as a first input the chaotic code output of the chaotic code source and as a second input a received radar signal, and as an output an indication of the correlation of the first and second inputs.

2. The radar system of claim 1, wherein the chaotic code source includes a source of a one-dimensional chaotic code source map.

3. The radar system of claim 1, wherein the chaotic code source includes

a chaotic map generator having as an input a selectable seed value or an immediately prior output of the chaotic map generator, and as an output a current output of the chaotic map generator, and

a quantizer having as an input the current output of the chaotic map generator.

4. The radar system of claim 1, wherein the encoder includes

a multiplier having as a first input the radar carrier signal and as a second input a time series of the chaotic code source, and as an output a modulated transmitted radar signal.

5. A radar system, comprising:

means for transmitting a transmitted radar wave having a wave form determined according to a chaotic code; and

means for receiving a reflection of the transmitted radar wave from an object and for determining a characteristic of the object from the reflection of the transmitted radar wave.

6. The radar system of claim 5, wherein the means for transmitting includes

a chaotic code source that produces a chaotic code, and

a transmitter including

a carrier signal source of a carrier signal, and

an encoder having as a first input the carrier signal of the carrier signal source and as a second input the chaotic code of the chaotic code source, and as an output a transmitted radar signal.

7. The radar system of claim 5, wherein the means for receiving includes

a correlator having as a first input a chaotic code and as a second input the reflection of the transmitted radar wave.

8. The radar system of claim 5, wherein the means for receiving includes

a plurality of correlators, each correlator having as a first input a sequence of chaotic code and as a second input the reflection of the transmitted radar wave.

9. The radar system of claim 8, wherein each correlator utilizes a different sequence of chaotic code.

10. A radar system, comprising:

means for transmitting a transmitted radar wave having a wave form determined according to a chaotic code; and

a receiver, comprising

a multielement delay line having as an input a received baseband radar signal and as an output a plurality of copies of the received baseband radar signal that are temporally offset from each other,

a correlator including

a multiplier having as a first input a sequence of the chaotic code and as a second input the plurality of temporally offset copies of the received baseband radar signal produced by the delay line, and having as an output a bit-by-bit product of the sequence of the chaotic code and each copy of the received baseband radar signal, and

an adder that adds the bit-by-bit products for each copy of the received baseband radar signal.

11. The radar system of claim 10, wherein the means for transmitting includes

a chaotic code source that produces a chaotic code, and

a transmitter including

a carrier signal source of a carrier signal, and

an encoder having as a first input the carrier signal of the carrier signal source and as a second input the chaotic code of the chaotic code source, and as an output a transmitted radar signal.

12. The radar system of claim 10, the receiver comprising

a plurality of correlators, each correlator including

a multiplier having as a first input a sequence of the chaotic code and as a second input the plurality of temporally offset copies of the received baseband radar signal produced by the delay line, and having as an output a bit-by-bit product of the sequence of the chaotic code and each copy of the received baseband radar signal, and

an adder that adds the bit-by-bit products for each copy of the received baseband radar signal.