...Digital Signal Processing The acronym DSP can stand for one of two things: digital signal processing which refers to the technique used to process signals digitally or digital signal processor which would refer to a specialized kind of microprocessor. Since the introduction of general-purpose microprocessors in the 1980’s, a wider range of modern technology now includes digital signal processing technology. This includes cellular phones, CD players, computers, DVD players, video recorders, computer monitors, and many other similar devices. DSP is also taking over analog circuitry in TV sets and telephones. One of DSP’s major applications is signal compression and decompression. Signal compression enables things such as call waiting and image projection on computer screens. DSP involves a great deal of math, both complex and simple. The design of a DSP chip enables it to perform these functions very rapidly which produces hundreds of millions of samples very quickly. This provides “real time” performance meaning the signal is live. This can be seen in loud speakers and cell phones. Most major electronics companies utilize DSP in their technology including Texas Instruments, Intel, and Motorola. An example of “real time” performance could be viewed in a lab that we did. We had two separate groups: one group made a “receiver” and the other group made a “transmitter.” Across the room, one group had their receiver and set up the microphone on a stand a certain amount of space...
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...1. Chapter 16, Harris CRYSTAL SETS TO SIDEBAND © Frank W. Harris 2006, REV 10 Chapter 16 ANCIENT MODULATION And other topics When I got back into ham radio 9 years ago, my ham friends told me that amplitude modulation (AM) was extinct. I was under the impression that SSB was the only mode of HF phone permitted. Later I learned that AM isn't actually illegal and there are a few diehards using AM on the 75 and 10 meter phone bands. I've also heard AM stations on 15 and 160 meters. In short, you might find a use for it. Besides, it's an interesting challenge to AM-modulate a transistorized transmitter. Homebuilt AM Back in the vacuum tube days many of us built our own transmitters and AM modulators. My first AM transmitter was a Heathkit DX-20. That was a 50 watt, CW, kit-built, vacuum tube transmitter to which I added a homebuilt AM modulator. Unlike SSB, AM could be added onto an existing CW transmitter. Rather than generate a low power AM signal and then amplify it with a linear amplifier, in the old days the usual method was to AM-modulate the final amplifier of the CW transmitter. On an oscilloscope, the hallmark of AM is that, when you are not speaking, the RF carrier wave runs continuously at an average power. That is, in AM the highest peak power and zero power only occur at the very highest voice peaks. Although I could see these transient peaks 2. Chapter 16, Harris on the scope, when I tried to catch...
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...TTL Cookbook BY Don Lancaster A Division of M t i c e Hall ComputerPublishing 11 711 Nonh College, Cmel, Indiana 46032 USA " 1974 by SAMS A Division of Prentice Hall Computer Publishing. All rights reserved. No parts of this book shall be reproduced, stored in a retrieval system, or transmitted by any means. electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. While every precaution has been taken in the preparation of this book, the publisher assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein. International Standard Book Number: 0-672-21035-5 Library of Congress Catalog Card Number: 73-90295 Interpretation of the printing code: the rightmost double-digit number of the first column is the year of the book's printing; the rightmost double-digit number of the second column, the number of the book's printing. For example, a printing code of 92-23 shows that the twenty-third printing of the book occurred in 1992. Printed in the United States of America. Preface I don't like to revise books. Correct, yes. Revise, no. So I won't. A book becomes history the instant it appears in print. To tamper with history messes with what others and I were thinking at the time and distorts the way things...
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