Ground Surveillance Radars (GSRs) help safeguard border lines, military and civilian installations and infrastructure. With local security challenges in mind, several GSR vendors are looking closely at the Asia-Pacific.
In Asia-Pacific, as elsewhere, ground threats to national borders pose a serious problem, particularly at times when insurgency is high. To combat this, Ground Surveillance Radars (GSRs) play an instrumental role in helping to protect sensitive areas. Increasingly, these radars are also called upon to help detect Unmanned Aerial Vehicles (UAVs). Although not a replacement for optronics, radar is attractive as a tool to support ground surveillance. It may not be adversely affected by low visibility, fog or haze in the same way as optronics. Secondly, it is immune to camouflage; a person will still show up on a radar regardless of how good their camouflage is.
Design of GSRs
Mark Radford, co-founder and chief executive officer of Blighter Surveillance Systems says that a number of considerations must be factored into the design of GSRs intended for the Asia-Pacific: “For GSRs to be effective in this region, they need to be robust and low maintenance to cope with the environmental extremes of -30 degrees Celsius (-22 degrees Fahrenheit) in winter and a humid +40ºC (104ºF) in summer.” A written statement from Collins Aerospace, which builds the PSR-500 GSR (see below), emphasised the drivers for the GSR market in the Asia-Pacific including “the growing need for the protection of secure sites, critical infrastructure, military bases, camps and assets against current and emerging threats.”
Radford adds that “political instability in many parts of this region serves to intensify the need for an effective surveillance solution.” For Steen Trier, Terma’s director of sales for the company’s surveillance and mission systems, demand for GSRs in the defence domain still outstrips that of the civilian domain, although demand in the latter is increasing: “The needs (of the) defence sector usually outnumbers the rest, due to the need for military perimeter and border protection. We also see an increasing interest from end-users involved in ensuring security in the energy, transportation and communications sectors.”
Traditionally, GSRs are used to detect people and vehicles. They are increasingly being employed to detect low-flying UAVs and drones. Such targets may fly relatively close to the ground, typically at altitudes of up to 500 feet (152 metres). This can place such flying objects squarely within the elevation FOV of some GSRs. Moreover, a UAV or drone’s size can make its detection by conventional ground-based air surveillance radars difficult.
These aircraft can present a threat as they can be used to gather reconnaissance and, in nefarious cases, carry explosives. This March is was reported that the YPG/PKK Kurdish separatist group had made up to twelve attempts to target Turkish military bases in the southeast of the country with explosive-laden drones. The attacks are believed to have originated from Kurdish-controlled areas in Syria. Fortunately on this occasion the attacks were foiled.
Thales has taken these threats into account with the realisation of the company’s Squire Mk.2 GSR. The Squire Mk.2, like its predecessors, is an X-band (8.5 gigahertz/GHz to 10.68GHz) GSR with an instrumented range of up to 45 kilometres/km (28 miles). X-band is an attractive waveband for GSRs. The short wavelengths of X-band transmissions lets such radars detect targets in fine detail. This is an important consideration when it is necessary to depict targets such as people crawling and moving vehicles, and to discriminate them from animals.
X-band radars achieve such a performance using comparatively small-sized antennas, allowing them to be moved with relative ease; a Squire radar can be carried by two people in backpacks. The trade-off is that X-band radars have a comparatively short range compared to lower frequency radars transmitting in S-band (2.3GHz to 2.5GHz/2.7GHz to 3.7GHz) and L-band (1.215GHz to 1.4GHz). Nevertheless, this is an acceptable compromise.
A GSR will typically be required to look several kilometres out from a base to provide early warning of approaching potentially hostile troops or vehicles. Such ranges may also be sufficient to protect a border from people attempting to cross it illegally. All radars are, to an extent, restricted to a line-of-sight range. Therefore one may as well use a radar providing a detailed depiction of targets within its line-of-sight.
Thales’ Squire Mk.2
Thales’ Squire Mk.2 includes a new processor and an embedded, uncooled infrared camera. Its detection range for a person has been increased to 13km (eight miles), compared to the 10km (six miles) of the previous version. Regarding counter-drone performance, Thales officials told the author that the radar can detect a drone at 2.7 nautical miles/nm (five kilometres) and classify that drone at 2.2nm (4km) range. The radar can also measure the altitude of such targets.
Thales added that existing Squire radars can be upgraded to the Squire Mk.2 specification. This is already being done for the Koninklijke Landmacht (Royal Dutch Army) which is upgrading 70 of its radars to Squire Mk.2 status. The first upgraded radars will be delivered to the force by the final quarter of 2019. The Canadian Army has, meanwhile, received new Squire Mk.2 radars.
Collins Aerospace has been energetically promoting its PSR-500 C-band Frequency Modulated/Continuous Wave (FMCW) perimeter protection radar. The company states that this product “combines all functionalities for ground intrusion detection, such as the efficient detection of moving targets, night and day whatever the weather conditions.”
Its statement goes on to say that the PSR-500 “is a low power, lightweight and easily-deployable system, well adapted for the surveillance of various types of sites.” The radar can detect a person at a range of 500m (1,640ft) and a vehicle at 900m (2,952ft). Many radars employ Pulse Doppler techniques to determine the speed of a target relative to the radar.
Pulse Doppler radars
The radar transmits a pulse of Radio Frequency (RF) energy which travels at the speed of light, 161,825 knots-per-second (299,700 kilometres-per-hour). By halving the time it takes for the radar to transmit a pulse, and then receive that pulse’s echo as it is reflected by the target, one can ascertain the target’s distance from the radar. Exploiting the Doppler Effect enables the measurement of the target’s velocity.
An oft quoted example of the Doppler Effect is the seemingly rising tone of a police car’s siren when approaching a stationary observer, and the seemingly declining tone that it makes as it drives away. This is because the sound waves take a progressively shorter time to reach the observer as the police car approaches and progressively longer as it drives away. Pulse Doppler radars exploit this change in frequency of the echoes to determine a target’s speed.
FMCW work in a different way. Whereas Pulse Doppler radars transmit a pulse of RF energy an FMCW radar transmits a continuous signal. The signal’s frequency will change over a set time pattern as the signal is swept across a set bandwidth. The radar will record which frequency was transmitted at which particular time, and record the frequency of the echo when the signal hits a target. These two signals (original signal and the echoed signal) will be mixed together thus creating a new signal. It is this latter signal that will be processed to determine the target’s distance and velocity.
FMCW are less complex to construct than their pulse Doppler counterparts, and hence can be less expensive. Such radars can also have a small physical size making them easy to transport and install, and use comparatively less power making them not only less expensive to operate, but potentially harder to detect by electronic support measures. FMCW radar is particularly attractive for applications where the user may need to procure several GSRs, such as to position along a border, or to protect the perimeter of a base.
Blighter’s GSRs employ a mix of FMCW and Doppler processing. The company has enjoyed success with its B-400 series Ku-band (13.4GHz to 14GHz/15.7GHz to 17.7GHz) systems which have an instrumented range of up to 25km (15.5 miles) for a large vehicle, and 4.6km (2.9 miles) for a crawling person. They can detect a target moving as slow as 0.37 kilometres-per-hour (0.23 miles-per-hour).
The FOV of the B-400 series is dependent on the number of antennas used therein. The baseline B-402 has a 90 degree horizontal FOV using a single antenna. This can be increased to 360 degrees for the B-442 which employs four antennas. As Radford notes these azimuths allow “hills, mountains, plains, riverine territories and marshes to be scanned simultaneously, without the need to tilt the radar.” Meanwhile, the 20 degree elevation beam width “provides detection of low flying manned aircraft, UAVs and drones, which is a growing concern in most border or coastal security applications.”
In 2010 Blighter began supplying B-400 series radars to equip the DMZ (Demilitarised Zone); the de facto border between the Republic of Korea and the Democratic People’s Republic of Korea. The firm supplied 120 examples of these radars to this end, Radford notes. Procurements of the B-400 have also been made by India. These radars equip the Indian government’s Comprehensive Integrated Border Management System (CIBMS). The CIBMS introduces several technologies, including radar, to improve the surveillance of India’s borders with Bangladesh and Pakistan.
The Danish radar specialists are looking closely at the Asia-Pacific as a market for its SCANTER-1002 ground surveillance radar. Transmitting in Ku-band, this radar has an instrumented range of up to twelve kilometres (7.4 miles), detecting a person at 3.7km (2.2 miles) and performing continuous scanning across a 360 degree radius.
Trier says that this radar is currently “deployed and operational in a number of Critical Infrastructure Protection systems in the Middle East and in the USA where it is used to provide enhanced situational awareness to protect sensitive sites and strategic assets.”
He says that the “Asia-Pacific market holds a large number of interesting opportunities.” Trier continues that the company has “identified several projects within the military, paramilitary and civilian areas (in the Asia-Pacific) for which high resolution area surveillance is very important.”
The Asia-Pacific Market
Collins Aerospace expects the need for GSRs to grow in the Asia-Pacific: “Demand for the protection of secure sites and critical infrastructure will increase. Leveraging current and future technologies such as drones and artificial intelligence to detect, identify and contain threats will increase the need for GSR in the Asia-Pacific,” the firm’s statement argues.
Radford agrees saying that the potential threat emanating from drones and UAVs is driving the market: “The ability to simultaneously detect drones and ground targets is key to enhancing security when drones are commonly used for surveillance as a precursor to the physical (action) by the transgressors themselves.”
The drive to protect key sites and military deployments against drones has been noted by Terma with Trier stating that “the detection and tracking of drones represent a real threat since their incursion not only disrupts civilian infrastructure (such as airports) but (can also) be a threat to lives and valuable assets.”
Radford expects a plethora of security challenges to continue driving the demand for GSRs in the Asia-Pacific: “We are receiving increased enquiries for our ground and coastline security radars to help secure borders and coastlines against a multitude of threats including smuggling, terrorism, people-trafficking and illegal immigration.”
Security challenges show no signs of abating in the Asia-Pacific. Fortunately, ground surveillance radars can play an important role in helping to keep such challenges in check.