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Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Marketing Manager Sharon Lightner Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman, VK2ZLZ John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Philip Watson, MIREE, VK2ZPW Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 1a/77-79 Bassett Street, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. PUBLISHER'S LETTER Remote control security is suspect Over the last month or so, there have been reports in the media about the security of UHF remote controlled burglar alarms as used in cars. It is now possible for car thieves to obtain a specially designed UHF receiver which can record the pulse coded signal from a remote handpiece and then transmit it again to open the car, after the owner is out of sight. As you might expect, this has caused consternation amongst car owners because in effect, if they use one of these UHF remote controlled burglar alarms, they are leaving their cars unlocked and with the burglar alarm disabled. The only solution, for owners of these existing burglar alarms, is to use an additional steering wheel lock, which rather defeats the convenience feature of UHF remote control. For car and burglar alarm manufacturers, their alarms need to be modified so that they use a “rolling code” whereby the code transmitted is changed each time the handpiece is used. Some cars already have this feature. Alternatively, UHF transmission could be dispensed with and infrared remote control used instead, albeit with less range available. It was only a matter of time before this clandestine UHF receiver/transmitter was used by car thieves in Australia. In fact, some car burglar alarm manufacturers have known about this device for several years and surprisingly, have done nothing about it. But even if the device had not become available, the necessary equipment is already available to someone who is devi­ous enough to want to do it. What do you need? A scanner receiver that can pick up 304MHz, a recorder to record the detected pulse modulation and then a UHF remote handpiece which can be modulated with the recorded signal. Simple. Alternatively, you could dispense with the scanner receiver and just use the UHF receiver section of a car burglar alarm. Lest readers think that I should not outline this information, let me state that you don’t have to be too clever to think of it. The security problem is not just confined to cars either. What about remote controlled garage doors? They use the same principles of operation and so anyone who has one of these doors that gives access to their home should be aware of the risk. And if I’ve thought of it, you can be sure that burglars are way ahead of me. The solutions are the same – use a rolling pulse code or infrared remote control, or possibly an inductive loop receiver buried in the driveway. Or just lock the door with a key. Leo Simpson ISSN 1030-2662 WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 2  Silicon Chip