Page 26

EETE NOVEMBER 2012

DESIGN & PRODUCTS AUTOMOTIVE ELECTRONICS Enabling the car to know which door to release A single two-way ranging exchange between one in-vehicle unit and a fob, while sufficient to measure how far away the fob is from the vehicle, is not sufficient to determine on which side of the vehicle the fob is located because only one piece of infor- mation – a single distance – is available. in order to determine on which side of the vehicle the owner (wearer of the fob) is located, two pieces of information are required, two distances from two in-vehicle units for example, provided of course that these in-vehicle units are positioned in an appropriate way. if the two units are mounted across the ve- hicle as shown in figure 1, then it becomes possible to uniquely identify the side of the vehicle on which the fob is located. hence, in our previous late night car park example, the locking mechanism of the boot would be released automatically as the woman approaches the rear of the car to store her luggages. Choosing a correct implementation Fig. 2: Choosing a correct implementation through the DecaWave’s technology is based on the propagation of ra- placement of communication nodes. dio waves from the transmitter to receiver. the technology is exceptionally good in non-line-of sight- environments but like time stamps to measure the distance between the fob and all radio schemes it will not propagate through metal plates; it the car it would be very difficult to intercept and “hijack” the can only propagate around them. this has important implica- messages being transmitted by the fob so that the car believes tions for the location of the in-vehicle units. Positioning the units there is a genuine 2-way ranging exchange in progress from a low down in the interior of the vehicle will severely restrict their fob close to the car. What’s more, the ieee802.15.4a standard “visibility” of the outside environment. hence, integrating them on which is based the single chip cMOs ultra-Wideband ic behind dashboards, door panels and the like will not work well. from Decawave supports Aes-128 encryption making it even On the contrary, positioning the units high up in the headlining, more difficult to interpret and modify the transmitted messages. the courtesy light, the sun visor mounts or other such elevated position will give a much better view of the outside environment, Reliability and flexibility via the windows glass, and will give better performance – see Because the scensor node uses ultra Wideband technology figure 2. it is very immune to fading due Multipath propagation. this is particularly important in indoor environments with signifi- Immune to relay attacks - by design cant amounts of metal such as in indoor car parks. scensor existing key fobs solutions can be intercepted using a scheme has excellent non-Line-of-sight and Line-of-sight range, this known as “relay attack”. imagine a vehicle owner sitting in a leaves the system designer decide on the distance within which restaurant with his car parked several blocks away. the key the in-vehicle system should take action on receipt of a valid fob in his pocket is transmitting regularly “looking” for the car exchange. the highly accurate distance measurement capabil- but the car is out of range. it is possible, with the right equip- ity allows the system to reliably determine if the fob is inside ment, for a person to pick up those transmissions, relay them to the vehicle, which will be the condition for starting the engine. another person close to the car and thereby open the car and Other benefits of using the IEEE802.15.4a protocol is the high drive away. data rates supported, which translates in very short on-air time Manufacturers are constantly looking for technologies to help and minimizes power consumption. What’s more, the protocol counteract this sophisticated method of theft, and DecaWave’s incorporates a number of error checking methods to ensure uWB technology can give them a new and powerful weapon communications is reliable. the frequency used is license free in in that battle. Because 2-way ranging is used with very precise most regions of the world so this solution can be used globally. 3-in-1 programmable automotive driver processor system tightly integrated with FPGA technology, assistance solution the Zynq-7000 enables ADAs-optimized “platforms” to which the ArM-processor based Zynq-7000 all programmable automakers and their electronics suppliers can add their own platform released by Xilinx is specifically geared towards intellectual property, along with off-the-shelf IP available in the deployment of automotive driver assistance systems Xilinx’s automotive ecosystem. the customizable nature of (ADAs). Where traditional solu- these platforms also shortens product development cycles tions employed an FPGA, a DsP and the time-to-market for applications including surround and a processor chip, the Zynq- vision, 3D surround vision, rear view cameras, dynamic 7000 combines the capabilities calibration, pedestrian detection, rear lane departure warn- of all three devices, with a 25% ing and blind spot detection. The fully AEC-Q100 qualified XA reduction in BOM and running Zynq-7000 devices will ship the second quarter of 2013 in two with approximately 50% less capacities, 28k and 85k logic cells. power, according to the manufac- Xilinx turer’s estimates. With its ArM dual-core cortex-A9 MPcore www.xilinx.com 26 Electronic Engineering Times Europe November 2012 www.electronics-eetimes.com


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