# US 11,307,290 B2 · Synchronous side lobe jamming method for electronic attack

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- Number: US 11,307,290 B2
- Document ID: US11307290B2
- Status: Granted
- Kind: B2
- Application number: 16/379,955
- Filed: 2019-04-10
- Published: 2020-07-09
- Granted: 2022-04-19
- Earliest claimed: 2019-01-04
- Assignees: Agency for Defense Development
- Applicants: Agency for Defense Development
- Inventors: Soyeon Kim; Sangwon Kim; Dongkeun Lee; Unseob Jeong
- Web page: https://patentgrep.com/patent/US11307290B2

## CPC

- G01S 7/021: {Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals}
- G01S 7/38: Jamming means, e.g. producing false echoes
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A synchronous side lobe jamming method for an electronic attack is disclosed. The method includes receiving a radar signal from an external radar; determining the number of synchronous jamming signals based on pulse repetition interval (PRI) characteristic of the received radar signal; generating a synchronous side lobe jamming signal by calculating a generation angle and a generation distance of each of the synchronous jamming signals; and transmitting the generated synchronous side lobe jamming signal to the radar at a predetermined delay time after a jammer receives a side lobe signal.

## Claims

### Claim 1

A synchronous side lobe jamming method by a jammer for an electronic attack, the synchronous side lobe jamming method comprising:
receiving a radar signal including a synchronous side lobe signal from an external radar;
determining the number of synchronous side lobe jamming signals based on pulse repetition interval (PRI) of the received synchronous side lobe signal;
generating the synchronous side lobe jamming signals by calculating a generation angle and a generation distance of the synchronous side lobe jamming signals; and
transmitting the generated synchronous side lobe jamming signals to the radar after the jammer receives the side lobe signal so that one or more virtual false targets are generated at particular positions and angles based on adding a time delay to the generated synchronous side lobe jamming signals,
analyzing a PRI characteristic of the received radar signal, including selectively determining to perform one of synchronous side lobe jamming and noise side lobe jamming based on an analysis results of the PRI characteristic of the radar signal,
wherein, when the PRI characteristic is a predictable pulse train according to the analysis results of the PRI characteristic of the radar signal, it is determined to perform synchronous side lobe jamming, and the PRI characteristic of the predictable pulse train includes a pattern PRI pulse train having at least one of a pulse train having a fixed/constant PRI and a pulse train having a PRI that is not fixed/constant, and
wherein, when the PRI characteristic is an unpredictable pulse train according to the analysis results of the PRI characteristic of the radar signal, it is determined to perform noise side lobe jamming,
wherein a scan period (Tscan) of the radar is calculated through Equation 1 below to calculate the generation angle of the synchronous side lobe jamming signals,
T
s
⁢
c
⁢
a
⁢
n
=
T
p
⁢
e
⁢
a
⁢
k
⁢
2
-
T
peak
⁢
⁢
1
360
+
θ
d
⁢
i
⁢
f
⁢
f
×
360
(
Equation
⁢
⁢
1
)
Here, Tpeak1 is a time when the jammer first received a main lobe signal emitted from the radar, and Tpeak2 is a time when the jammer received the main lobe signal after the first received main lobe signal, θdiff denotes an angle difference between the main lobe signal at times of Tpeak1 and Tpeak2,
wherein, θdiff is calculated by Equation 2 below,
θ
d
⁢
i
⁢
f
⁢
f
=
{
θ
p
⁢
e
⁢
a
⁢
k
⁢
2
-
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
,
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
-
θ
peak
⁢
⁢
2
,
⁢
if
⁢
⁢
(
(
mod
⁢
⁢
360
⁢
(
θ
peak
⁢
⁢
2
-
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
)
<
1
⁢
8
⁢
0
)
⁢
⁢
and
⁢
⁢
(
D
s
⁢
c
⁢
a
⁢
n
=
C
⁢
W
)
)
or
⁢
⁢
(
(
mod
⁢
360
⁡
(
θ
p
⁢
e
⁢
a
⁢
k
⁢
2
-
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
)
≥
180
)
⁢
⁢
and
⁢
⁢
(
D
scan
=
CCW
)
)
⁢
else
(
Equation
⁢
⁢
2
)
here, θpeak1 and θpeak2 denote angles of the main lobe signal at Tpeak1 and Tpeak2, respectively, and mod 360(⋅) is modular arithmetic for 360 degrees, modular arithmetic is a computation method that defines the sum and the product of integers for the remainder of a given number, Dscan is a scanning rotation direction of the radar, CW is a beam of the radar rotates in a clockwise direction, and CCW is a beam of the radar rotates in a counterclockwise direction,
wherein a direction θ in which the main lobe signal indicates a jammer-mounted platform on the basis of the radar is calculated through Equation 3 below when the globe is assumed to be a perfect sphere,
θ(Φr,λr,Φac,λac)=a tan 2(sin(λac−λr)·cos(Φac)·cos(Φr)·sin(Φac)−sin(Φr)·cos(Φac)·cos(λac−λr)) (Equation 3)
here, ϕr is a latitude of the radar, λr is a longitude of the radar, ϕac is a latitude of the jammer-mounted platform, and λac is a longitude of the jammer-mounted platform, and
wherein, a direction θft of each of the false targets to be generated is calculated by applying resultant values of the Equations 1 to 3 to the following Equation 4 below.
θ
f
⁢
t
⁡
(
t
)
=
mod
⁢
360
⁡
(
t
-
T
peak
⁢
⁢
2
T
s
⁢
c
⁢
a
⁢
n
×
360
+
θ
p
⁢
e
⁢
a
⁢
k
⁢
2
)
.
(
Equation
⁢
⁢
4
)

### Claim 2 (depends on 1)

The synchronous side lobe jamming method of claim 1, wherein the PRI characteristic of the predictable pulse train further includes one of staggered, jittered, wobulated, sliding, and dwell and switch (D&S).

### Claim 3 (depends on 1)

The synchronous side lobe jamming method of claim 1, wherein a time for the radar to receive the synchronous slide lobe jamming signal is calculated by adding all of a time for the jammer to receive a side lobe signal of the radar, a delay time for the jammer to transmit the synchronous side lobe jamming signal, and a value obtained by subtracting a timing at which the jammer transmits the synchronous side lobe jamming signal from a timing at which the radar receives the synchronous side lobe jamming signal.

### Claim 4

A synchronous side lobe jamming performing apparatus for an electronic attack, the synchronous side lobe jamming performing apparatus comprising:
a signal receiver receiving a radar signal including a synchronous side lobe signal from an external radar;
a signal analyzer analyzing pulse repetition interval (PRI) characteristic of the received radar signal;
a synchronous jamming signal generator determining the number of synchronous side lobe jamming signals and calculating a generation angle and a generation distance of each of the synchronous side lobe jamming signals to generate at least one synchronous side lobe jamming signals when the PRI characteristic is a predictable pulse train;
a jamming signal transmitter outputting the synchronous jamming signal generated by the synchronous jamming signal generator to the radar after a jammer receives the side lobe signal so that one or more virtual false targets are generated at particular positions and angles based on adding a time delay to the generated synchronous side lobe jamming signal; and
a controller controlling operations of the signal receiver, the signal analyzer, the synchronous jamming signal generator, and the jamming signal transmitter,
wherein the controller determines to perform synchronous side lobe jamming when the PRI characteristic is a predictable pulse train according to the analysis results of the PRI characteristic of the radar signal, and the PRI characteristic of the predictable pulse train includes a pattern PRI pulse train having at least one of a pulse train having a fixed/constant PRI and a pulse train having a PRI that is not fixed/constant, and
wherein the controller determines to perform noise side lobe jamming when the PRI characteristic is an unpredictable pulse train according to the analysis results of the PRI characteristic of the radar signal,
wherein a scan period (Tscan) of the radar is calculated through Equation 1 below to calculate the generation angle of the synchronous side lobe jamming signals,
T
s
⁢
c
⁢
a
⁢
n
=
T
p
⁢
e
⁢
a
⁢
k
⁢
2
-
T
peak
⁢
⁢
1
360
+
θ
d
⁢
i
⁢
f
⁢
f
×
360
(
Equation
⁢
⁢
1
)
here, Tpeak1 is a time when the jammer first received a main lobe signal emitted from the radar, and Tpeak2 is a time when the jammer received the main lobe signal after the first received main lobe signal, θdiff denotes an angle difference between the main lobe signal at times of Tpeak1 and Tpeak2,
wherein, θdiff is calculated by Equation 2 below,
θ
d
⁢
i
⁢
f
⁢
f
=
{
θ
p
⁢
e
⁢
a
⁢
k
⁢
2
-
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
,
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
-
θ
peak
⁢
⁢
2
,
⁢
if
⁢
⁢
(
(
mod
⁢
⁢
360
⁢
(
θ
peak
⁢
⁢
2
-
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
)
<
1
⁢
8
⁢
0
)
⁢
⁢
and
⁢
⁢
(
D
s
⁢
c
⁢
a
⁢
n
=
C
⁢
W
)
)
or
⁢
⁢
(
(
mod
⁢
360
⁡
(
θ
p
⁢
e
⁢
a
⁢
k
⁢
2
-
θ
p
⁢
e
⁢
a
⁢
k
⁢
1
)
≥
180
)
⁢
⁢
and
⁢
⁢
(
D
scan
=
CCW
)
)
⁢
else
(
Equation
⁢
⁢
2
)
here, θpeak1 and θpeak2 denote angles of the main lobe signal at Tpeak1 and Tpeak2, respectively, and mod 360(⋅) is modular arithmetic for 360 degrees, modular arithmetic is a computation method that defines the sum and the product of integers for the remainder of a given number, Dscan is a scanning rotation direction of the radar, CW is a beam of the radar rotates in a clockwise direction, and CCW is a beam of the radar rotates in a counterclockwise direction,
wherein a direction θ in which the main lobe signal indicates a jammer-mounted platform on the basis of the radar is calculated through Equation 3 below when the globe is assumed to be a perfect sphere,
θ(Φr,λr,Φac,λac)=a tan 2(sin(λac−λr)·cos(Φac)·cos(Φr)·sin(Φac)−sin(Φr)·cos(Φac)·cos(Φac)·cos(λac−λr)) (Equation 3)
here, ϕr is a latitude of the radar, λr is a longitude of the radar, ϕac is a latitude of the jammer-mounted platform, and λac is a longitude of the jammer-mounted platform, and
wherein, a direction θft of each the false targets to be generated is calculated by applying resultant values of the Equations 1 to 3 to the following Equation 4 below.
θ
f
⁢
t
⁡
(
t
)
=
mod
⁢
360
⁡
(
t
-
T
peak
⁢
⁢
2
T
s
⁢
c
⁢
a
⁢
n
×
360
+
θ
p
⁢
e
⁢
a
⁢
k
⁢
2
)
.
(
Equation
⁢
⁢
4
)