024-025-026_EETE-VF

EETE NOVEMBER 2012

DESIGN & PRODUCTS AUTOMOTIVE ELECTRONICS Secure car access: when proximity is the key By Gerry O’Grady Picture the scene. it’s late at night, dark, raining. A tired businesswoman approaches her car in the airport car-park, and sighs wearily as she puts down her files, laptop and luggage, searching through her bags and jacket for her key fob to unlock her car. in the adjacent car-parking space, her colleague - similarly burdened down with files, laptop and luggage - simply walks to her car reaches out and the car boot unlocks as she opens it. she places her luggage in the boot, sits into the driving seat, presses the start button and salutes her struggling colleague as she drives away. From next year onwards, this will be the reality of new keyless entry systems for the automotive industry using the power and precision of DecaWave’s ultra wideband technology. Automobile manufacturers will only take up the technology if it Fig. 1: Determining on which side of the vehicle the wearer of meets a number of basic but essential criteria. the fob is approaching. the technology must be able to operate in crowded car parks both indoors and outdoors, granting vehicle access within a relatively short distance of the vehicle. such a keyless entry Identifying the distance from the vehicle system should not be permitted to start the engine unless the Measuring the distance of the fob to the vehicle is not a prob- driver is inside the car, which means it should be capable of lem since DecaWave’s uWB technology allows distance to be determining precisely when the key fob is inside the vehicle. As measured with an accuracy of +/-10cm based on time-of-flight. well as being inexpensive and low power for several years of A single transceiver in the vehicle can conduct a 2-way ranging battery operation, the system must be secure enough to prevent exchange with the key fob, when the appropriate key fob button potential thieves from “hijacking” communications between the is pressed and calculate the distance from the fob to the vehi- key fob and the vehicle to gain access to the vehicle. Of course cle. the tiny radio unit allows Line-of-sight ranges greater than conformance with local regulations, in all geographies where the 200m. However, the in-vehicle unit can be configured to only manufacturer’s vehicles are sold, is a pre-requisite. take action when the measured distance is less than a certain value defined by the vehicle manufacturer. Thus, in the example Gerry O’Grady is Applications engineering Manager at above, when our driver comes to within a specified short range DecaWave – www.decawave.com of the vehicle, the lock release mechanism is triggered. DESIGNSPARK See us at Hall A4, NEW. FREE. Stand 117 MODELSOURCE OVER 80,000 FREE SCHEMATIC AND PCB SYMBOLS IN MORE THAN 20 FORMATS, INCLUDING PADS, ORCAD, ALTIUM AND CADSTAR. Discover today at www.designspark.com RESOURCES BYUNIQUE 24 Electronic Engineering Times Europe November 2012 www.electronics-eetimes.com


EETE NOVEMBER 2012
To see the actual publication please follow the link above