12 Technology And

It is important to understand the origin and the migration of EMC issues which have developed as a result of technological innovations during the last century. At the beginning of the 20th century, the technology of the day with regard to communications consisted primarily of generating high frequency radio signal by generation of high-voltage discharges. The systems were used to send short messages and allowed experimentation with propagation characteristics and high-frequency transmissions....

103governmental Requirements

The governmental requirements vary from country to country regarding frequencies and emissions levels. In the United States, the Federal Communications Commission (FCC) has the authority to establish and enforce radiated emissions requirements from electronic devices. These are contained in the Commission's rules from the Office of Engineering and Technology and are documented in the Title 47 portion of the Federal Rules and Regulations. Within Title 47 is Part 15, which covers radio frequency...

933 SCR Noise

Another example of BB noise generation is from silicon controlled rectifier (SCR) controlled devices. Using a SCR to control the voltage to an AC operated device means that the sine wave is truncated at some point in its waveform. By doing this, the waveform starts to look like a portion of a square wave, with (as discussed earlier) harmonic content. This can be heard by listening to an AM radio while an incandescent lamp dimmer is used to control a lighting circuit in the same room. Some of...

Kluwer Academic Publishers

NEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW eBook ISBN 1-4020-7783-1 Print ISBN 1-4020-7713-0 New York, Boston, Dordrecht, London, Moscow Print 2004 Kluwer Academic Publishers Dordrecht No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America Visit Kluwer Online at http kluweronline.com and Kluwer's eBookstore

Courtesy ETSLindgren used with permission

In other portions of the text, a detailed discussion of transmission lines was reviewed. Here we will repeat some of the key ones. They are 1) Flexible usage (can be routed easily) 2) Impedance designed to match most test equipment impedance 3) Self shielding aspects - unlike open wire line The coax types that are most often used are * RG-58, a flexible small diameter moderately lossy cable for short runs and jumpers RG-59, a small flexible 70 ohm cable for video RG-174, a thin flexible cable...

911 Emc Issue Immunity To External Fields

One of the most important items to realize is that electronic systems (especially microprocessor and complex systems) operate with various signals and data. Many of these signals consist of operation on various clock frequencies that may extend well into the frequency ranges that are being used for RF communication, which may result in systems inadvertently reacting to the external sources of energy instead of the intended signal and or data that is actually desired. If we look at the RF...

104fcc Part

The decade ofthe 1970's saw tremendous advances in digital electronics. In 1979 the FCC established rules for digital device radiated emissions for clock speeds greater than 9 kHz. For any digital devices that are marketed today (9 kHz is several orders of magnitude slower than today's devices), all such devices marketed must meet the FCC requirements for both conducted emissions and radiated emissions. Devices are classified according to their intended operating environment as either Class A...

93 Broadband Noise

It is easy to observe the effects of BB noise from an electric motor. There are examples in everyday applications, such as vacuum cleaners or mixers being operated in a home. It is not even necessary to have high power for the noise generation. Many cordless battery operated devices can emit enough energy to generate BB noise. There are many types applications of motors in many environments, and of course, automotive systems also use many motors. These are used to adjust seat positions, open...

105 Microvolts Per Meter And Watts

Watts are the units used to describe the amount of power generated by a transmitter. Microvolts per meter (fiV m) are the units used to describe the strength of an electric field created by the operation of a transmitter. A particular transmitter that generates a constant level of power (Watts) can produce electric fields of different strengths depending on, among other things, the type of transmission line and antenna connected to it. Because it is the electric field that causes interference...