GB2535708A

GB2535708A - Apparatus and method for locating a radio signal source

Info

Publication number: GB2535708A
Application number: GB1503020.8A
Authority: GB
Inventors: Jones Michael; Pearce Jonathan
Original assignee: Roke Manor Research Ltd
Current assignee: Roke Manor Research Ltd
Priority date: 2015-02-24
Filing date: 2015-02-24
Publication date: 2016-08-31
Also published as: GB201503020D0

Abstract

This invention is for a device that can locate a GPS jamming signal. It includes a direction finder 210. Antennas 206A to 206D receive radio signals, and the receivers 208A to 208D each output a signal which is fed to the direction finder. There is also a combiner 216 that takes video data stream from a video camera 110 and produces a source indicator on the video data that corresponds to the radio signal source, i.e. the jamming signal. It may also include a video monitor that can display the video generated by the video camera with the one or more radio source indicators. There may also be a calibrator 212 that ensures that the video data stream from the video camera and the direction signal are aligned correctly. The camera and direction finder can also be combined into a single hand-held unit, as shown in figure 1.

Description

Apparatus and Method for Locating a Radio Signal Source The present invention relates to an apparatus and a method for dentifying the position of one or more radio signal sources in a video data stream.

Background to the Invention

The global positioning system (GPS) is used by a large number of devices in order to provide relatively precise location information. Generally speaking, the system is sufficiently robust that it is relied upon by critical infrastructure. However, the threat of commercial jammers to the effective operation of GPS is well known. In particular, the proliferation of low-cost GPS jammers represents a global problem, with demonstrable consequences to users of navigation and timing equipment. In the event of a jamming incident, there is a need to rapidly locate any jamming sources, so that they can be disabled promptly. There are various well-publicised jamming incidents in which it took the authorities several months to locate the source of interference and remove it.

There are now various systems in existence which are designed to help with the problem of GPS interference, but they typically all exhibit one or more of the following drawbacks. Firstly, such systems are typically difficult to install and deploy, with a need to install a number of fixed sensor nodes, in order to triangulate the transmission source. Secondly, many devices only provide azimuth sensing. Essentially, they only give the longitude and/or latitude of the jammer without being able to distinguish height.

Finally, most systems tend to be very expensive because they involve large fixed installations and sensor networks, making the costs prohibitively high.

Summary of the Invention

In a first aspect, the present invention provides an apparatus for identifying the position of one or more radio signal sources in a video data stream, the apparatus comprising: a video camera, arranged to produce a video data stream corresponding to an area of interest; a direction finder, arranged to determine the direction of one or more radio signal sources in the area of interest and to produce a direction signal, indicative of the direction of the one or more radio signal sources; a combiner, arranged to combine the video data stream and the direction signal to produce one or more source indicators corresponding to the one or more radio signal sources, overlaid on the video data stream, to provide a visual indication of the position of the one or more radio signal sources in the video data stream.

In a second aspect, the present invention provides a method for identifying the position of one or more radio signal sources in a video data stream, the method comprising: producing a video data stream corresponding to an area of interest; determining the direction of one or more radio signal sources in the area of interest and producing a direction signal, indicative of the direction of the one or more radio signal sources; combining the video data stream and the direction signal to produce one or more source indicators corresponding to the one or more radio signal sources, overlaid on the video data stream, to provide a visual indication of the position of the one or more radio signal sources in the video data stream.

In a third aspect, the present invention provides an apparatus for providing data identifying the position of one or more radio signal sources in a video data stream, the apparatus comprising: a video camera, arranged to produce a video data stream corresponding to an area of interest; and a direction finder, arranged to determine the direction of one or more radio signal sources in the area of interest and to produce a direction signal, indicative of the direction of the one or more radio signal sources.

In a fourth aspect, the present invention provides a method for providing data identifying the position of one or more radio signal sources in a video data stream, the method comprising: producing a video data stream corresponding to an area of interest; and determining the direction of one or more radio signal sources in the area of interest and producing a direction signal, indicative of the direction of the one or more radio signal sources.

In a fifth aspect, the present invention provides an apparatus for locating a radio signal source, the apparatus comprising a video camera, a radio signal direction finder, and a video monitor, the apparatus arranged to display video generated by the video camera, together with one or more radio source indicators, the source indicators based on a direction signal generated by the radio signal direction finder.

In a sixth aspect, the present invention provides a method for locating a radio signal source, the method comprising displaying video generated by a video camera, together with one or more radio source indicators, the source indicators based on a direction signal generated by a radio signal direction finder.

Further features of the invention are defined in the appended dependent claims.

Brief Description of the Drawings

By way of example only, the present invention will now be described with reference to the drawings, in which: Figure 1 shows a perspective view of a handheld jammer detector in accordance with an embodiment of the present invention; Figure 2 shows a schematic diagram of a circuit layout of the handheld jammer detector shown in Figure 1; Figure 3 shows an antenna array in accordance with an embodiment of the present invention; Figure 4 is a flow chart showing a method of calibration of the handheld jammer detector of Figure 1; Figure 5 shows a screen-shot of a video stream produced by the handheld jammer detector shown in Figure 1; Figure 6 shows a screen-shot of a video stream produced by the handheld jammer detector shown in Figure 1; Figure 7 is a flow chart showing a method of operation of the handheld jammer detector of Figure 1; and Figure 8 shows a screen-shot of a video stream produced by the handheld jammer detector shown in Figure 1.

Detailed Description of Preferred Embodiments

A first embodiment of the present invention will now be described in connection with the Figures.

Figure 1 shows a handheld jammer detector 100. The jammer detector 100 includes a main housing 102 which is arranged to house the electronic components of the detector 100, as will be described in more detail below. The jammer detector 100 also includes a handle 104. The handle 104 is attached to the main housing 102 such that a user may easily direct the jammer detector 100 towards an area of interest. The jammer detector 100 also includes an antenna array housing 106. The antenna array housing 106 is positioned at a front end of the main housing 102. The antenna array housing 106 is arranged such that when a user wishes to point the device toward an area of interest, the antenna array housing 106 is positioned closest to, and in the direction of, the area of interest.

In this embodiment, the antenna array housing 106 includes a circular front face 108. The front face 108 is a planar disc, behind which is located an antenna array. In the centre of the front face 108, there is a video camera 110. The video camera 110 and the front face 108 are aligned such that in a particular position they are both directed towards the same area of interest.

Figure 2 is a schematic diagram showing the layout of the electric circuit 2100 of the jammer detector 100. The circuit 200 includes the video camera 110, which is arranged to output a video data stream along connection 202. The circuit 200 also includes an antenna array 204, which consists of four identical antennas 206A, 206B, 206C and 206D. In response to a received radio signal, each of the antennas 206A to 206D generates a signal which is processed by a corresponding receiver 208A, 208B, 208C and 208D.

The circuit 200 also includes a direction finder 210. In use, when the antennas 206A to 206D receive radio signals, the receivers 208A to 208D each output a signal which is fed to the direction finder 210. The direction finder 210 processes the received signals and is able to determine the direction of the radio signal source. As the device includes four antennas, it is able to resolve up to three different radio sources at the same time. The direction finder produces a direction signal which provides information concerning the direction of the radio source. This information is fed together with the video data stream to calibrator 212.

Before the raw direction signal and the raw video data stream can be used, they must be calibrated. The purpose of the calibrator 212 is to ensure that the direction signal and the video data stream are aligned. The calibrator 212 includes a user input 214, which enables a user to calibrate the device. The calibrator 212 has two outputs. The first output is the raw video data stream. In this respect, the calibrator 212 does not adjust or alter the video data stream in any way. Secondly, the calibrator 212 outputs a calibrated direction signal. The calibrated direction signal is based on the direction signal, but has been calibrated so that it is aligned with the video data stream. The calibration process will be described in more detail below.

The circuit 200 also includes a combiner 216. The combiner 216 takes the video data stream and the calibrated direction signal as its inputs. The combiner 216 is arranged to produce a source indicator on the video data stream to correspond to the location of the radio signal source. This process will be described in more detail below. The combiner 216 produces a single output which is the enhanced video data stream.

Figure 3 shows the antenna array housing 106. However, in Figure 3 the front face 108 has been removed for clarity. Figure 3 shows the antenna array housing 106 from the front of the jammer detector 100. A primary axis of the camera 110 is oriented perpendicularly to the page. The camera 110 can be seen in the centre of the antenna array housing 106. In addition, the antennas 206A to 206D are shown in a diamond configuration. It will be appreciated that other antenna configurations are possible.

The process of calibrating the jammer detector 100 will now be described. In this connection, Figure 4 is a flowchart showing the steps involved in the process of calibration. Initially, the device is switched on so that the video camera 110 feeds a video data stream to the calibrator 212 (S400). The jammer detector 100 is positioned so that its field of view is directed towards a predetermined area of interest (A0I) (8402). A radio signal source (i.e. a jammer) is then placed in a predetermined location within the A01 (S404).

At this stage, the video camera 110 produces a video data stream which is fed to the calibrator 212. Furthermore, the direction finder 210 produces a direction signal which is also fed to the calibrator 212. Prior to calibration, both of the signals are fed unaltered to the combiner 216. The combiner 216 produces a source indicator which is overlaid over the video data stream. The combiner outputs an enhanced video data stream. This is fed to the screen 218. Figure 5 shows the image which appears on the screen 218 at this stage. As can be seen, the screen 218 shows the jammer 500, and the radio signal source indicator 502. As can be seen, the source indicator 502 is not properly aligned with the jammer 500. Using a suitable input device, the user is able to adjust the location of the indicator 502 on the screen 218 using user input 214 (S406).

Figure 6 shows the image produced on screen 218, which shows that the jammer 500 and the indicator 502 are aligned. Once the user is happy that the indicator and the video image are aligned, they indicate to the calibrator 212 via user input 214 that the signals are aligned, using a suitable input device (S408). Following calibration, the jammer detector is ready for use.

The operation of the jammer detector 100 will now be described in more detail. The jammer detector 100 has two primary modes of operation. Firstly, the jammer detector 100 may be used by a user to provide live video on the screen 218 in order to enable a user to identify the sources ofjamming signals. In a second mode, the video data stream and the calibrated direction signal are output by the detector for further processing. The further processing may be done on a live basis, or the signals may be stored for later analysis. In this mode, there is no need to present the enhanced video data stream on the screen 218. Instead, the calibrated direction signal could be used by number plate recognition software in order to indicate when and where in a digital video stream a number plate should be identified. In this mode of operation, the video stream is not displayed to a user. The aforementioned modes of operation may be used in combination, and the second mode of operation may be used in conjunction with live video.

Figure 7 is a flowchart showing the first mode of operation. Initially, a user switches on the jammer detector 100 (S700). The user then orientates the device towards an AOI (S702). At some point, one or more radio signal sources move within the AOI (S704).

One or more indicators then appear on the screen 218 (S706).

Figure 8 shows the screen 218 and includes three indicators 800A, 800B and 800C. As can be seen, these indicators overlap with three objection 802A, 802B and 8020. The user is then able to assume that the objects 802A, 802B and 802C are the sources of jamming signals. Further investigation can then be undertaken.

The jammer detector 100 provides a way of producing virtual three-dimensional location of a radio signal source. In fact, the device is producing a two-dimensional direction signal which has been overlaid over a two-dimensional video stream.

However, by overlaying the video stream with the direction information, the user is able to essentially produce the location determination in three dimensions. The user is able to determine based on the video image where the radio signal is likely to be originating. This provides an extremely low-cost way of simulating three-dimensional radio signal source location.

Features of the present invention are defined in the appended claims. While particular combinations of features have been presented in the claims, it will be appreciated that other combinations, such as those provided above, may be used.

The above embodiments describe one way of implementing the present invention. It will be appreciated that modifications of the features of the above embodiments are possible within the scope of the independent claims.

Claims

Claims 1. An apparatus for identifying the position of one or more radio signal sources in a video data stream, the apparatus comprising: a video camera, arranged to produce a video data stream corresponding to an area of interest; a direction finder, arranged to determine the direction of one or more radio signal sources in the area of interest and to produce a direction signal, indicative of the direction of the one or more radio signal sources; a combiner, arranged to combine the video data stream and the direction signal to produce one or more source indicators corresponding to the one or more radio signal sources, overlaid on the video data stream, to provide a visual indication of the position of the one or more radio signal sources in the video data stream.
2. An apparatus according to claim 1, wherein the direction finder includes an antenna array, arranged to receive the one or more radio signals.
3. An apparatus according to claim 2, wherein the antenna array is a two-dimensional array.
4. An apparatus according to claim 3, wherein the antenna array includes two or more antennas, and the antennas are arranged in a common plane, and the common plane is orthogonal to a primary axis of the antenna array.
5. An apparatus according to any of claims 2 to 4, wherein the camera and the antenna array are positioned such that they share a common field of view.
6. An apparatus according to claim 4, wherein the camera has primary axis which is aligned with the primary axis of the antenna array.
7. An apparatus according to any of claims 2 to 6, wherein the direction finder further comprises at least one receiver, coupled to the antenna array and arranged to receive the one or more radio signals and to produce at least one receiver output.
8. An apparatus according to claim 7, wherein the direction finder is arranged to determine the direction of the one or more radio signals and to produce the direction signal based on the at least one receiver output.
9. An apparatus according to any preceding claim, further comprising a calibrator arranged to align the direction signal and video signal
10. An apparatus according to any preceding, wherein the area of interest is a two-dimensional area, and the direction signal comprises the coordinates of the one or more radio signal sources relative to that area.
11. An apparatus according to any preceding claim, further comprising a video screen, wherein the combiner is arranged to output an enhanced video data stream to the screen and the screen is arranged to display the enhanced video stream.
12. A method for identifying the position of one or more radio signal sources in a video data stream, the method comprising: producing a video data stream corresponding to an area of interest; determining the direction of one or more radio signal sources in the area of interest and producing a direction signal, indicative of the direction of the one or more radio signal sources; combining the video data stream and the direction signal to produce one or more source indicators corresponding to the one or more radio signal sources, overlaid on the video data stream, to provide a visual indication of the position of the one or more radio signal sources in the video data stream.
13. An apparatus for providing data identifying the position of one or more radio signal sources in a video data stream, the apparatus comprising: a video camera, arranged to produce a video data stream corresponding to an area of interest; and a direction finder, arranged to determine the direction of one or more radio signal sources in the area of interest and to produce a direction signal, indicative of the direction of the one or more radio signal sources.
14. An apparatus according to claim 13, further comprising a calibrator, arranged to align the video data stream and the direction signal such that the direction signal provides the position of the radio signal source relative to the corresponding portion of the video data stream.
15. A method for providing data identifying the position of one or more radio signal sources in a video data stream, the method comprising: producing a video data stream corresponding to an area of interest; and determining the direction of one or more radio signal sources in the area of interest and producing a direction signal, indicative of the direction of the one or more radio signal sources.
16. A method according to claim 15, further comprising aligning the video data stream and the direction signal such that the direction signal provides the position of the radio signal source relative to the corresponding portion of the video data stream.
17. An apparatus for locating a radio signal source, the apparatus comprising a video camera, a radio signal direction finder, and a video monitor, the apparatus arranged to display video generated by the video camera, together with one or more radio source indicators, the source indicators based on a direction signal generated by the radio signal direction finder.
18. A method for locating a radio signal source, the method comprising displaying video generated by a video camera, together with one or more radio source indicators, the source indicators based on a direction signal generated by a radio signal direction finder.
19. An apparatus for performing the method of any of claims 12, 15, 16 and 18.
20. An apparatus substantially as hereinbefore described and as shown in the drawings.
21. A method substantially as hereinbefore described and as shown in the drawings.