Area or line surveillance has typically been achieved using a range of techniques and sensors which may promise a great deal but which all have limitations in one way or another.
For example, solid barriers and wire fences can provide a strong physical barrier. When lined with passive sensors, both beneath the ground and along the fence line, and linked to microwave intrusion detection systems backed up with CCTV, they can also provide an excellent alert and alarm capability. However, what they don’t provide is Early Warning. There is no development of a situational awareness picture. The threat is already on your doorstep by the time the system detects it.
Moreover, where the requirement is for surveillance of a large area, or where the terrain inhibits the construction of perimeter fencing, or where earlier warning that humans are operating near a restricted area is needed, then an alternative approach is clearly called for.
Situational awareness is now a core requirement for security operations, and those charged with airport perimeter protection and control are increasingly turning to radar. Using the radio wave area of the electro-magnetic spectrum, much longer detection ranges are possible as well as the penetration of cluttered environments such as sand storms, heavy rain, snow and fog.
There are now various radar manufacturers worldwide offering radar sensor devices as well as, in some cases, the software required for the application of perimeter security, surveillance, protection and intruder detection.
Kelvin Hughes has recently applied the principles of its SharpEye™ system to produce a lightweight solid state radar, the SharpEye™ SxV, which is designed to overcome some of the problems of airport perimeter and critical infrastructure surveillance applications.
There are a number of advantages of this technology. First, a pulse radar (as opposed to FMCW models) gives simultaneous short, medium and long range transmission and detection. Second, the provision of a rotating antenna provides 360 degree radar coverage. To achieve the same with a flat panel phased array system, for example, you would have to add more radars at the appropriate angles to get the area coverage. The single sensor required for a 360 degree radar cuts down considerably on cost, infrastructure and complexity. Third, the system operates in operator selectable frequencies within the X-Band, a frequency lower than the Ku, K and Ka bands typically used, thus considerably improving its ability to penetrate and work in bad weather. With its Doppler processing of the received pulse return, the receive module of the radar is able to process out (or filter) clutter without radar picture degradation through the application of complex algorithms. (‘Clutter’ is a term used to describe unwanted returns such as rain, snow, sand and moving grass).
X-Band Pulse radar outperforms FMCW radars in a number of areas. K, Ka and Ku-band radars suffer in long range performance when compared to X-Band, but more importantly are susceptible to interoperability issues such as interference or even jamming due to their broad transmission frequency.
A distinct advantage of the new solid state technology is its size and portability. It is now possible to produce a radar system small and light enough to be deployed in multiple field-based scenarios. A critical infrastructure location surrounded by a fence line or a wall can be protected with 360 degree radar coverage either from a central mast or at optimum positions on the perimeter. The elevated radar provides early warning of planned intrusion as well as the apparent point of breach. Should a response unit not be able to prevent an incursion, the radar will still track and follow intruders inside the fence perimeter, providing key information on the intruders’ intended destination. For mobile patrolling radars can be mounted on a retractable mast fitted to a vehicle. Surveillance can then be conducted over a very wide area, with the surveillance patrol able to move its position based on intelligence, covering known incursion points and areas frequently targeted by intruders or by operating from fresh locations to confuse intruders with a random patrol pattern.
The use of solid state electronics also means that peak power can be significantly reduced which, together with the pulsed waveform, makes it much less likely that anyone observing the frequency spectrum for detection devices will be able to identify the radar.
Of course, in order to determine a response to a potential threat detected by the radar, the precise nature of the target should be properly classified. Simple CCTV or powerful electro-optical cameras can be combined with the radar on the same mast, providing an integrated solution. Control and integration software is then used to take the radar video (pre-processed with the clutter removed) and provide targets on a screen overlaid with a geo-referenced map. Cameras can be directed onto targets and areas of interest by both day and night, and in all weathers. Imagery from the cameras is sent to the command centre or control room. Stills and video can be captured for use in immediate response decision making, future reference and can be sent to other mobile devices.
Kelvin Hughes’ CxEyeTM software runs on a windows platform and is compatible with touchscreen interfaces. It displays radar video on a main screen area overlaid with geo-referenced maps. Open source mapping from Bing, Google etc. are also accepted. In the top right corner is a real time video display showing the feed from an electro-optical camera, and within that picture (picture-in-picture) a feed from a thermal imaging camera is displayed. These camera feeds can be manipulated to provide a larger image simply by touching the area on the screen.
The slew-to-cue functionality enables the operator to simply touch with his finger a target of interest on the radar image and the camera for the area selected will immediately pan and zoom, focus on the target, and maintain a visual track of that target. The operator can apply a “radar” track identifier to the target, providing visual information on the movements of that track over a period of time. With the radar providing longitude and latitude coordinates of each moving target, plus its speed and direction, it is much easier to coordinate a response. The camera enables visual identification of a target detected by the radar, enabling the Operator to classify the target and the Commander to respond.
Thermal imaging or low-light cameras provide target identification by both day and night and in poor visibility.
CxEyeTM software provides clear and unambiguous situational awareness, providing early warning from the radar, a detailed picture evidence from the camera and the continuous tracking ability of the radar. Swift and simple classification of all tracks establishes what is happening, where and who is doing it. Controlled responses are facilitated with this clear “situational picture”.
In summary, there are significant security advantages to the use of modern pulse radar systems for land-based surveillance. Much improved situational awareness, Early Warning (as opposed to simply intruder alert), operational flexibility and adaptability, as well as a optimum Value For Money solution are all key benefits. Only one 360 degree radar is required to achieve full coverage of a protected area as opposed to multiple sensors. Finally, as a result of the high reliability of today’s solid state electronics, maintenance costs are significantly lower than those associated with traditional surveillance devices.
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