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Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) PUBLISHER'S LETTER Technical Staff John Clarke, B.E.( Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Sharon Macdonald Sales & Marketing Mgr. Sharon Lightner · Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX Marque Crozman John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc. , B.E. 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: Magazine Printers Pty Ltd, Alexandria, NSW; 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. Liability: 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. 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. ISSN 1030-2662 2 SILICON CHIP The oscilloscope - the everyday time machine This month, we have a feature article on oscilloscopes. This takes a look at some of the features of current model scopes, both analog and digital. It really only just touches on the subject, giving a glimpse of what these remarkable measuring instruments can do. When you think about it, we take the oscilloscope for granted. Want to take a look at a signal? Simple, just grab a probe, connect it up, flick a few switches and there it is on the screen. But what may be portrayed on the screen is often happening so fast that it is impossible for the human brain to really appreciate. Say you have a signal on the screen with a frequency of 100 megahertz. That's an absolutely routine frequency but you can display it easily on many scopes these days so that you can see the actual waveform, not just a signal envelope. Think about that waveform. Each cycle of the waveform on the screen is taking place in just ten nanoseconds. Such a time interval is so short that if were to regard a nanosecond as a second, an hour of our lifetime would last more than 100,000 years! And yet we look at those minute slices oftime as though they were nothing more remarkable than a pencil sketch. Which in a way is what they are; an accurate sketch sample produced automatically by the flying electron beam behind the screen. Think about how fast the electron beam has to move in order to accomplish that task. It is fairly easy to calculate how fast it is deflected up or down the screen but think how much faster it is going as it hits the back of the screen. But a 100MHz scope is just routine these days and it is only scopes that go up into the Gigahertz region that are regarded as really special. That's an order of magnitude better - or more. Truly then, today's oscilloscope is a veritable time machine - not one that allows us to travel forward or backwards in time but one which allows us to divide time into portions so small that time becomes meaningless. Think about that the next time you hook up your scope for a routine measurement. Leo Simpson