# US 9,429,655 B2 · Detecting and localization method of unknown signal using aircraft with ADS-B system

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- Number: US 9,429,655 B2
- Document ID: US9429655B2
- Status: Granted
- Kind: B2
- Application number: 14/517,169
- Filed: 2014-10-17
- Published: 2015-02-05
- Granted: 2016-08-30
- Earliest claimed: 2012-11-30
- Assignees: Korea Aerospace Research Institute
- Applicants: Korea Aerospace Research Institute
- Inventors: Youngsun Yun; Jeongho Cho; Moonbeom Heo; Giwook Nam
- Web page: https://patentgrep.com/patent/US9429655B2

## CPC

- G01S 19/21: Interference related issues {; Issues related to cross-correlation, spoofing or other methods of denial of service}
- G01S 5/0036: {of measured values, i.e. measurement on mobile and position calculation on base station}
- G01S 5/0072: {Transmission between mobile stations, e.g. anti-collision systems}
- G01S 5/011: {Identifying the radio environment}
- G01S 5/0215: {Interference}
- G01S 5/04: Position of source determined by a plurality of spaced direction-finders
- G01S 5/06: Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence)
- G01S 19/03: Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
- 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 method of detecting an unknown signal and estimating a source location of the unknown signal using aircraft based on an automatic dependent surveillance-broadcast (ADS-B) system is provided. The method includes a first step (S100) for obtaining from a plurality of airborne aircrafts provided with a network system, aircraft signals transmitted to an air traffic control (ATC) and a second step (S200) for detecting, by the ATC, a presence of an unknown signal in the aircraft signals based on one of a time difference of arrival (TDOA) method, a time of arrival (TOA) method, and an angle of arrival (AOA) method. The method further includes a third step (S300) for estimating the source location of the unknown signal and a fourth step (S400) for transmitting unknown signal generation information associated with the unknown signal and the source location of the unknown signal to neighboring aircraft and the ATC.

## Claims

### Claim 1

A method of detecting an interference signal and estimating a source location of the interference signal using network connected aircraft, the method comprising:
obtaining, by airborne aircrafts, GNSS signals transmitted from navigation satellites affected by the interference signal transmitted from the source location of the interference signal, and obtaining, by the airborne aircrafts, jammer to noise ratio (J/N) measurements from the GNSS signals affected by the interference signal;
transmitting, by the airborne aircrafts, from a plurality of airborne aircrafts provided with a network system to an air traffic control (ATC), jammer to noise ratio measurements, through the network;
detecting, by the air traffic control (ATC), a presence of the interference signal by analyzing the J/N measurements;
estimating, by the ATC, the source location of the interference signal using the J/N measurements; and
transmitting, by the ATC, the source location of the interference signal, to neighboring aircraft and a second ATC through a flight information services-broadcast (FIS-B) or a notice to airmen (NOTAM).

### Claim 2 (depends on 1)

The method of claim 1, wherein the estimating comprises:
estimating the source location of the interference signal based on an equation represented
d
⁢
⁢
J
i
⁢
⁢
j
=
J
i
-
J
j
=
10
⁢
α
⁢
⁢
log
10
⁡
(
ⅆ
j
ⅆ
i
)
,
wherein and Ji and Jj each denote a signal power of the interference signal received from receivers (i,j), α denotes a path loss index, and di and dj denote a distance from the source of the interference signal to the receivers (i, j).

### Claim 3 (depends on 1)

The method of claim 1, wherein the estimating comprises:
estimating the source location of the interference signal based on an equation represented by
dJij=JNRi−JNRj=(Ji−Ni)−(Jj−Nj)≈Ji−Jj,
wherein JNRi and JNRj each denote a J/N measurement in receivers (i, j), and Ni denotes noise of a receiver (i).