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Frequency failure - Radio towers disrupt smart key systems

Published:Sunday | February 21, 2016 | 12:00 AMDavion Smith
The push start/stop button of a motor vehicle.
A radio tower.

When Jennifer Allen purchased her 2012 Mazda CX-5 last December, equipped with a push-start keyless ignition system, she expected a more relaxed automotive experience. However, Allen has never missed the jingle of regular car keys more.

"It (the push-start ignition) is supposed to be better, they say, but give me the key ignition vehicle," Allen told Automotives.

Allen's preference for a good old-fashioned system where the key is inserted into the ignition results from the trouble she has been having at times getting into her Mazda, using the key fob/remote. "The thing is, every time I start the car I always have to remember to put the spare key (which can only be used to open or close the vehicle's doors) in my pocket. If it's left in the car 'yuh goose cook'. I have to have it on me, because the door doesn't open with the remote sometimes," she said.

The remote devices for push button start/stop vehicles are not only responsible for locking and unlocking the doors. They also play an indispensable role in starting the vehicle, as they must be in a particular range of the vehicle for the engine to be turned on. And Allen recalls an occasion when the engine would not start, despite the key being within the required range.

She does not know why a vehicle which she has been driving for only three months should be malfunctioning, but there is an explanation.

Mahlangu Lawson, a telecommunications engineer at the Spectrum Management Authority (SMA), told Automotives that the issues Allen has been experiencing are not uncommon, as the SMA has received numerous complaints from motorists.

Lawson explained that Allen's car trouble is not because of a fault with the vehicle, but occurs when it is in proximity to a radio station like at her workplace. The 'tech man' said key remote's operate on specific frequencies. Because of this radio towers, if close enough to the vehicle, can interfere with the signal being transmitted between remote and car.

"There is something called intermodulation. If, for argument sake, more than one radio tower is transmitting in the same vicinity, when those two signals mix or come together in a non-linear device it may create frequencies outside the designated frequency. If your remote operates on any of those frequencies it is possible that this radio signal is jamming your remote system," Lawson said.

So if, like Allen, a motorist operates a vehicle with a push-start ignition system or simply owns a car with a remote that locks and unlocks the vehicle doors, it is helpful to be aware of radio towers when parking.