Signal jammers not seen as a threat to tracker devices

Car theft is unfortunately a grim reality we have to live with in South Africa and car tracking devices are often punted as the answer for the security-conscious. So allegations of jamming devices that can block tracker signals are alarming to say the least. Tracking companies, however, are adamant that these devices do not present a threat. If a car owner does want to take precautions, they should know what type of tracking device is installed in their vehicle.

Tracking companies use two types of devices and the essential difference is the way that the signal is transmitted – one uses GSM technology or cellphone networks and the other uses RF or radio frequency signals. Jerry Pierce, the operations manager at Cartrack, which only uses GSM-tracking devices, says GSM technology is considered more modern than RF technology. “GSM trackers are equipped with a sim card which communicates via SMS. Depending on the tracker package you buy, the technology can get more sophisticated. For example, some devices use GPRS to stream data every 30 seconds,” he says.

Radio frequency vs cellphone signal

Signal jamming devices or GSM jammers have been around for years and work by blocking GSM-signals. Harry Louw, the managing director of Altech Netstar, says a jammer effectively blocks signals in the range of about 850-950 Mhz and the 1 800 Mhz band. “Netstar owns a proprietary radio frequency, way below these frequencies, which is used to activate our RF units and cannot be jammed with an off-the-shelf jammer,” he says. However, Louw cautions that while 90 per cent of Netstar’s trackers are RF units, about 10 per cent are GSM units, which can be jammed by a GSM jammer. Netstar released a message to subscribers this week, reassuring them that jamming devices are not widely used and should not be seen as a major threat.

Gareth Crocker, the communications manager at Tracker, says while in certain applications GSM jammers can be effective, they have their limitations. “Tracker has known about these devices for years and has developed a number of key security protocols and countermeasures to ensure that their effect on our tracking units is marginal at best,” he says. To illustrate the point, Crocker notes that Tracker’s recovery rate has remained consistently high since the mid-90s, despite these jamming devices being freely available on the market. Crocker says Tracker has heard rumours of devices that can be used to jam an RF signal but have not been able to find any proof of this. He says in South Africa alone, Tracker has recovered almost 65 000 stolen and hijacked vehicles, which has led to 11 500 arrests.

Not a threat

Pierce concurs that there are GSM jammers available on the black market, which can be used to jam cellphones and these devices could also block a tracking signal. “You have to remember though, that these devices are geo-specific with, for example, a two-metre radius. This means the jammer has to be within a two-metre radius of the tracking device and has to be activated continuously in order to block the signal effectively,” he says.

“If jammers are used, it is so infrequent that we don’t see it as a threat. Our response times are so quick that we often find the suspects still in the vehicle. We have never found jammers at a crime recovery scene. Hijacking and car theft criminals operate in groups and often use cellphones to communicate, so it doesn’t make sense for them to use a GSM jammer,” he says.

Built-in precautions

Pierce notes that Cartrack devices have a built-in security precaution which uses a back-up RF signal to alert the company if an attempt is made to jam the GSM signal on the device. Brendan Horan, the managing director of Mix Telematics, agrees that jamming devices are not a new phenomenon. “While we clearly recognise that there is no fool proof security device, our systems and services continually prove to be extremely effective against a myriad of threats including jamming devices,” he says.

Crocker points out that in some cases, where a car is parked in an underground basement with a steel roller door, it is possible that a GSM signal could be cut off. “However, an RF signal is strong enough to penetrate that environment so consumers should ideally be checking what sort of signal their tracking device uses,” he says.

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