Generation of a family of orthogonal signals for a CDMA radar system

Patent metadata

Field	Value
Publication number	US-10996326-B2
Application number	US-201816189045-A
Country	US
Kind code	B2
Filing date	Nov 13, 2018
Priority date	Nov 13, 2018
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

A system and method to generate a family of orthogonal signals for a code division multiple access (CDMA) radar system involve selecting a first signal of the family of orthogonal signals for transmission by one of a plurality of transmitters of the radar system. The method includes using an algorithm to determine a second signal of the family of orthogonal signals. The algorithm uses cross-correlation values between candidate signals for consideration as the second signal of the family of orthogonal signals and the first signal. The method also includes transmitting the first signal of the family of orthogonal signals and the second signal of the family of orthogonal signals simultaneously from two different transmitters, and obtaining and processing reflections resulting from transmission of the first signal of the family of orthogonal signals and the second signal of the family of orthogonal signals.

First claim

What is claimed is:

1. A method of generating a family of orthogonal signals for a code division multiple access (CDMA) radar system, the method comprising:
selecting a first signal of the family of orthogonal signals for transmission by one of a plurality of transmitters of the radar system;
using an algorithm to determine a second signal of the family of orthogonal signals, wherein the algorithm uses cross-correlation values between candidate signals for consideration as the second signal of the family of orthogonal signals and the first signal;
transmitting the first signal of the family of orthogonal signals and the second signal of the family of orthogonal signals simultaneously from two different transmitters;
obtaining and processing reflections resulting from transmission of the first signal of the family of orthogonal signals and the second signal of the family of orthogonal signals;
iteratively using the algorithm to determine additional signals of the family of orthogonal signals, wherein the algorithm uses cross-correlation values between each candidate signal for consideration as one of the additional signals of the family of orthogonal signals and all previously determined ones of the family of orthogonal signals;
generating each of the candidate signals by changing only a parameter value a from the first signal of the family of orthogonal signals and others of the candidate signals; and
deriving factors w, k1 and k2 that are used to generate the candidate signals from the parameter value α as follows:

w
=

α
⁢

⁢
β

π

k
1

=

2
⁢

⁢

arctan
⁡

(

B

2
⁢
wT

)

k
2

=

sec
⁡

(

k
1

⁢
T

2

)

,

where
B is a bandwidth of each of the candidate signals and T is a duration of each of the candidate signals.

2. The method according to claim 1 , wherein the changing the parameter value a changes a curvature of the candidate signals.

3. The method according to claim 1 , wherein the generating the candidate signals includes determining instantaneous frequency f(t) and phase φ(t) of each of the candidate signals as:

f
⁡

(
t
)

=

w
⁢

⁢

tan
⁡

(

k
1

⁢
t

)

⁢

sec
⁡

(

k
1

⁢
t

)

k
2

φ
⁡

(
t
)

=

2
⁢
π
⁢

⁢
w
⁢

⁢

sec
⁡

(

k
1

⁢
t

)

(

k
1

⁢

k
2

)

.

4. The method according to claim 1 , wherein the using the algorithm includes obtaining a sum associated with each candidate signal as a sum of the cross-correlation values between the candidate signal and all previously determined ones of the family of orthogonal signals, and identifying a selected signal among the candidate signals as the candidate signal that results in a lowest value of the sum associated with each candidate signal.

5. The method according to claim 1 , wherein the using the algorithm includes identifying a maximum associated with each candidate signal as a maximum value among the cross-correlation values between the candidate signal and all previously determined ones of the family of orthogonal signals that is less than or equal to a threshold value, and identifying a selected signal among the candidate signals as the candidate signal that results in a minimum of the maximum associated with each candidate signal.

6. The method according to claim 5 , further comprising increasing the threshold value when the selected signal is not identified.

7. The method according to claim 1 , wherein the using the algorithm includes identifying a maximum associated with each candidate signal as a maximum valu

Assignees

• Gm Global Tech Operations Llc

Inventors

• Solodky Gaston
• Longman Oren
• Villeval Shahar
• Bilik Igal

Classifications

• G01S13/325 Primary

  using transmission of coded signals, e.g. P.S.K. signals · CPC title

• G01S13/284 Primary

  using coded pulses · CPC title

• G01S7/023

  Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36) · CPC title

• G01S7/354

  Extracting wanted echo-signals (Doppler systems G01S13/50) · CPC title

• H04B7/0413

  MIMO systems · CPC title