Orthogonal phase modulation for detection and communication in radar

Patent metadata

Field	Value
Publication number	US-10768273-B2
Application number	US-201816612223-A
Country	US
Kind code	B2
Filing date	May 9, 2018
Priority date	May 10, 2017
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A method of orthogonal modulation of radar waves of a phase-modulated continuous wave radar system. The method includes selecting an equidistant bi-phased or multi-phased phase-modulation sequence, phase-modulating the continuous radar wave, and transmitting the orthogonal phase-modulated continuous radar wave towards a scene. The method includes generating a detection sequence (s) by applying an outer coding (H) to the phase-modulation sequence, selecting a communication range (C) in the complex number plane, based on the selected phase-modulation, generating a communication sequence (c) having a plurality of sequence members, mapping the communication sequence (c) into the communication range (C) by applying an injective mapping function (Γ) to the sequence members, and calculating a numerical product of members of the detection sequence (s) with members of an image of the mapped communication sequence (c). Phase-modulating the continuous wave of the radar system is carried out according to the calculated numerical products.

First claim

The invention claimed is:

1. A method of orthogonal modulation of radar waves of a phase-modulated continuous wave radar system by a sequence of numerical communication symbols, the method comprising steps of:
selecting an equidistant bi-phased or multi-phased phase-modulation sequence, wherein members of the sequence are given by complex roots of unity,
phase-modulating the continuous radar wave of the radar system, and
transmitting the orthogonal phase-modulated continuous radar wave towards a scene,
and the method being characterized by the following steps of:
generating a detection sequence (s) by applying an outer coding (H) to the bi-phased or multi-phased phase-modulation sequence,
selecting a communication range (C) in the complex number plane, based on the selected equidistant bi-phased or multi-phased phase-modulation,
generating a communication sequence (c) comprising a plurality of sequence members, wherein the members are natural numbers,
mapping the communication sequence (c) into the communication range (C) by applying an injective mapping function (Γ) to the members of the communication sequence (c),
calculating a numerical product of members of the detection sequence (s) with members of an image of the mapped communication sequence (c),
wherein the step of phase-modulating the continuous radar wave of the radar system is carried out according to the calculated numerical products.

2. The method as claimed in claim 1 , wherein the selected equidistant bi-phased or multi-phased phase-modulation sequence is selected from a group comprising m-sequence, Zadoff-Chu sequence, Legendre sequence or Almost Perfect Autocorrelation Sequence.

3. The method as claimed in claim 1 , wherein the phase-modulated continuous wave radar system is configured to work in a multiple-input and multiple-output configuration, and the step of generating a detection sequence (s) includes applying a Hadamard matrix (H).

4. The method as claimed claim 1 , wherein the injective mapping function (Γ) can be expressed as:

Γ
⁡

(
c
)

=

exp
⁡

(

i
⁢

π
⁡

(

2
⁢
c

-

(

T
+
1

)

)

n
⁡

(

T
+
1

)

)

wherein c denotes the value of a member of the communication sequence (c), n denotes the maximum possible number of different roots of unity for the members of the equidistant bi-phased or multi-phased phase-modulation, and T denotes the maximum value of the members of the communication sequence (c).

5. A method of demodulating phase-modulated continuous radar waves that are orthogonally modulated by a sequence of numerical communication symbols by the method as claimed in claim 1 , wherein the phase-modulated continuous radar waves are directly received, the method comprising steps of:
applying a communication backprojection function Ω to the received phase-modulated continuous radar waves for mapping the numerical communication symbols to the communication range (C), wherein the communication backprojection function Ω can be expressed as:

Ω
⁡

(

c
~

)

=

∑

k
=
0

n
-
1

⁢

χ
⁢

⁢

c
k

⁡

(

c
~

)

⁢

e

-
2

⁢
π
⁢

⁢
i
⁢

k
n

⁢

c
~

,

wherein n denotes the maximum possible number of different roots of unity for the members of the equidistant bi-phased or multi-phased phase-modulation, {tilde over (c)} is an image of a member of the communication sequence (c) in the communication range (C), and χ C k ({tilde over (c)}) is the characteristic function with a value of 1 if the argument lies within the subset C k of the complex unit circle and a value of 0 else, and
extracting the numerical communication symbols by applying the inverse function of the injective mapping function (Γ) to images of the mapped numerical communication symbols in the communication range (C).

6. A method of demodulating phase-modulated continuous radar waves that are orthogonally modulated by a sequence of numerical communication symbols by the method as claimed in claim 1 , wherein the phase-modulated continuous radar waves are received after having been reflected by a target, the method comprising steps of:
applying a detection sequence backprojection function Δ to the received phase-modulated continuous radar waves for projecting all phases lying in a specific subset of

Assignees

• Iee Sa
• Univ Luxembourg

Inventors

• Schroder Udo
• Beise Hans-Peter
• Spielmann Thiemo
• Dokhanchi Sayed Hossein

Classifications

• 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

• G01S7/0233

  Avoidance by phase multiplex · CPC title

• G01S7/0234

  Avoidance by code multiplex · CPC title

• G01S13/325

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

• G01S13/878

  Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector (G01S13/874 takes precedence) · CPC title