Radar Applications in the Modern Surveillance Environment

Drone Radar
Drone Radar

Much is discussed today regarding the urgent importance of radars for detection of the new and growing Drone and UAV/UAS threat. Reality is however that irrespective of these developments, radar as a general technology has being undergoing massive growth and development during the last few decades.

Motivation seems to have been based on a number of factors. In the military environment, it is probably fair to say the inherent limitations of electro-optical sensors are now better understood. In the civilian market, demands are expanding for radar sensors in many areas. It seems obvious that most vehicles will be equipped with radars within the very near future. Adventurous soothsayers might also forecast that, as example, all streetlights will soon be fitted with small networked radar systems.

Growth has been derived from requirements and needs, but has also been able to capitalise on many technological advances. What was once only possible with extremely complex and expensive analog signal processing can now be “easily” (whereby this term should be used with care) realised with software defined radar processing. Advances with high-speed and high-performance analog-digital converters, high bandwidth data-transfer paths, and powerful digital-processing devices and main computers means that signal processing can be conducted with a sophistication that was impossible only a few years back. And at prices that could hardly be imagined for earlier generation radars.

New radar technologies have also been able to share advances made in the volume communications field. Whereby this is not without problems: already now we are seeing difficulties with frequency allocations.

Perhaps easily overlooked, it must nevertheless be appreciated that digital signal processing is with limits. Despite these advances, overall sensor performance is still very much dependent on the quality of baseline radio-frequency components. A good example is that the antenna is still one of the most important components of any radar system. Likewise, transmitter characteristics, general phase and frequency stability and precision, and component noise-characteristics are still prime determinants of what can genuinely be extracted with signal processing. High quality RF and hardware components are priced accordingly, which seems to suggest that it is still a truism that with radar, you generally get what you pay for.

General Radar Processing

Radar is a generic term, and covers many technologies and applications. When reduced to surveillance radars with a volume coverage about 50km, this subset alone covers a huge range of solutions such as Pulse, CW, Rotating, Fixed Panel, Phased Array, AESA and Digital Array. Likewise, frequencies will typically be between S and X-Band, with some specialised solutions at Ku or Ka-Band.

It would be ideal to claim that one combination can provide the absolutely best solution to all applications and requirements. This is however not the case : design involves any number of compromises and optimisations in order to obtain a radar which maximises performance for a particular target set and system-wide needs. All solutions will have advantages and disadvantages, and will try to balance conflicting demands such as space-and-weight, power-consumption, elevation-coverage, update-rate, detection and classification ranges, track-accuracy, environmental conditions and the like. And not least, cost.

Weibel radars are designed to satisfy a wide spectrum of these surveillance requirements by introducing a family of Surveillance Radars with a common backbone of hardware and software components. Performance differences are implemented by selection of product and application specific component arrangements, whereby the key to all these radars is advanced FM/CW-waveform Digital-Array processing.

Further, a specialised Stop-and-Stare function means that the Weibel SHORAD radar family offer functionality that combines the benefits and cost-advantages of Rotating radars with those of Fixed Panel Array Radars.

SHORAD
SHORAD

Classification

A major trend is the requirement for improvement in Target Classification. The need for robust and high-quality classification has been known for some time – indeed, demands probably go back to the end of the Cold War, and the increasing military involvement in difficult low-intensity military operations where classification, recognition and identification are critical. Added to this is the rapid growth in demand to both detect and classify Drone and UAV/UAS Targets.

At a sensor level, the outcome is that while Surveillance sensors were traditionally defined by parameters such as Coverage, Detection Performance, Track Accuracy and Reaction-Times; Classification performance (typically Target Class definition and Range) is now added to performance criteria.

Target Classification is a complex problem. With the technologies available today, it seems reasonable to expect that reliable classification to a precise level of differentiation will need a multi-sensor approach. Advances are already being made with electro-optical image-processing ; our expectation is that full classification will be achieved through data-fusion of image and radar-based classifications. That is, while all sensors will contribute, final classification will be at the system-level.

At Weibel, our designs are based on the approach that information in a radar sense is best measured as a function of time-on-target. That is, the 100% duty-cycle processing of modern MF/CW and FM/CW radars will encapsulate the highest information content and permit the greatest flexibility in signal processing and extraction.

Weibel radar signal processing is designed to extract not just Range and Angular data, but also Target-specific information that can support class-differentiation. Information processing is currently based on advanced analysis of the very precise Doppler information that is an inherent characteristic of CW radars.

Way-Ahead

Radar technology and products are going through a challenging and exciting phase where advances in hardware and signal processing technologies are used to satisfy growing and changing User requirements. These advances are likely to continue for the foreseeable future : many changes will be incremental, others (as example, changing emphasis in frequency bands) will be more significant.

To remember is that measures will always be limited by unchanging and elementary laws such as those described by the classic radar equation.