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Selection and Operation of Wireless Microphone Systems (English) SELECTION AND OPERATION WIRELESS MICROPHONE SYSTEMS Updated for digital wireless By Tim Vear A Shure Educational Publication SELECTION AND OPERATION WIRELESS MICROPHONE SYSTEMS Updated for digital wireless By Tim Vear Selection and Operation of Table of Contents WIRELESS Microphone Systems Introduction ........................................................................ 4 Other Radio Services .................................................. 34 Non-Broadcast Sources .............................................. 34 Part One Range of Wireless Microphone Systems ..................... 35 Wireless Microphone Systems: How They Work Spread Spectrum Transmission .................................. 35 Digital Wireless Systems ............................................. 36 Chapter 1 Operation of Wireless Systems Outside of the U.S. ..... 39 Basic Radio Principles ....................................................... 5 Radio Wave Transmission ........................................... 5 Part Two Radio Wave Modulation .............................................. 7 Wireless Microphone Systems: How To Make Them Work Chapter 2 Chapter 4 Basic Radio Systems ......................................................... 8 Wireless System Selection and Setup ............................... 40 System Description ..................................................... 8 System Selection ......................................................... 40 Input Sources ............................................................. 8 Crystal Controlled vs. Frequency Synthesis ................. 41 Transmitter: General Description ................................. 9 System Setup: Transmitter........................................... 41 Transmitter: Audio Circuitry ......................................... 10 System Setup: Receivers ............................................. 43 Transmitter: Radio Circuitry ......................................... 11 System Setup: Receiver Antennas............................... 45 Receiver: General Description ..................................... 12 System Setup: Batteries............................................... 46 Receiver: Radio Circuitry ............................................ 13 System Checkout and Operation ................................. 47 Receiver: Audio Circuitry ............................................. 14 Computer-Controlled Wireless Systems ....................... 48 Receiver: Squelch ....................................................... 14 NEW “Intelligent” Wireless Systems...................................... 48 Receiver: Antenna Configuration ................................ 15 Troubleshooting Wireless Microphone Systems ........... 49 Multipath .................................................................... 15 Troubleshooting Guide ................................................ 49 Receiver: Diversity Techniques ................................... 16 Antennas .................................................................... 18 Chapter 5 Antenna Cable ............................................................ 20 Application Notes ............................................................... 50 Antenna Distribution ................................................... 21 Presenters.................................................................... 50 Musical Instruments .................................................... 50 Chapter 3 Vocalists....................................................................... 51 Wireless System Operation ................................................ 23 Aerobic/Dance Instruction ........................................... 52 Frequency Bands for Wireless Systems ...................... 23 Theater ........................................................................ 52 VHF ............................................................................ 23 Worship........................................................................ 53 UHF ............................................................................ 25 Bingo ........................................................................... 53 NEW Why UHF? .................................................................. 26 Film/Videography......................................................... 54 Frequency Selection ................................................... 26 Broadcast .................................................................... 54 System Compatibility ................................................... 26 Point-to-Point Wireless................................................. 55 Operating Frequency Interactions: Conclusion................................................................... 58 Intermodulation .......................................................... 26 Internal Frequency interactions: LO, IF, Reference Information Crystal Multipliers ........................................................ 28 Appendix A: Calculation of Non-System Radio Interference .................................. 30 Intermodulation Products ........................................... 59 Broadcast Television ................................................... 30 Appendix B: U.S. Television Channels ........................ 61 Wireless Systems in the Post-DTV Transition Era ........ 32 Glossary of Terms and Specifications .......................... 62 NEW White Space Devices .................................................. 33 Included Illustrations ................................................... 65 Broadcast Radio ......................................................... 34 Biography ................................................................... 66 Wireless 3 Selection and Operation of WIRELESS Microphone Systems Introduction In the 60 years since their introduction, wireless microphone some similarities between sound transmission and radio systems have developed from experimental devices to the transmission, many of the characteristics of radio systems present range of proven technologies. At the same time their are neither analogous to audio systems nor intuitive to the use has evolved from a mere performance novelty to audio engineer. Therefore, some necessary basic radio a universal feature in productions of every type. Finally, principles are included in the presentation. a steadily improving ratio of performance vs. cost has ultimately made the wireless microphone as affordable The purpose of this guide is to provide the interested as it is reliable. reader with adequate information to select suitable wireless equipment for a given application and to use that However, even as wireless products have become more equipment successfully. In addition, it is hoped that the capable and accessible, they are being used in ever more fundamentals presented here will equip regular users complex applications. In addition, the radio environment of wireless with a framework to assist in their further has become much more crowded and problematic than understanding of this evolving technology. before. Advances such as digital technology have helped to meet these changing requirements, but challenges are This guide is presented in two parts: how wireless likely to increase. As a result, even simple wireless microphone systems work and how to make wireless microphone applications must be designed and installed microphone systems work. The first part is a technical with care to insure their successful operation. introduction to the basic principles of radio and to the characteristics of wireless transmitters and receivers. The scope of this guide is limited to wireless systems used The second part discusses the practical selection and primarily in audio applications. Although most of the operation of wireless microphone systems for general and examples are given in terms of wireless microphones, the specific applications. The two parts are intended to be same radio and audio principles apply to wireless in-ear self-contained. The first part should be of interest to those monitors, wireless intercoms, and other similar audio trans- who specify or integrate professional wireless equipment mission systems. The reader is presumed to be somewhat while the second part should be of use to anyone who familiar with typical audio systems. However, while there are regularly works with wireless microphone systems. Introduction 4 Selection and Operation of WIRELESS PART ONE: Wireless Microphone Systems: How They Work Microphone Systems CHAPTER ONE presently known, humans are directly sensitive to radio waves only at frequencies in the range of a few million GHz, BASIC RADIO PRINCIPLES which are perceived as visible light, and at those frequencies in the range just below visible light, which are perceived as heat (infrared radiation). The overall radio Radio Wave Transmission spectrum includes both natural and artificial sources as Radio refers to a class of time-varying electromagnetic indicated by Figure 1-2. fields created by varying voltages and/or currents in The amplitude of a radio wave is the magnitude of the certain physical sources. These sources may be "artificial," field variations. It is the characteristic that determines the such as electrical power and electronic circuits, or "natural," "strength" of the radio wave. Specifically, it is defined to be such as the atmosphere (lightning) and stars (sunspots). the amplitude of the electric field variation. It is measured The electromagnetic field variations radiate outward from the in volts per unit length and ranges
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