doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 1 Wireless Microphone Characteristics IEEE P Wireless RANs Date: Authors: Notice: This document has been prepared to assist IEEE It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at >

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 2 Abstract This presentation covers the basic technical and operational characteristics of wireless microphones. It is provided at the request of the Spectrum Sensing Tiger Team.

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 3 Wireless Microphone Characteristics Wireless Microphones are low power licensed secondary users of the television spectrum. Their primary application is real-time high quality audio transmission over short distances (< 300m). Wireless microphones are at the front end of the audio chain, and are often used live. Noise bursts and dropouts are not tolerated, and are perceived as a product quality/reliability issue by users. There is no second chance to re-do a live event.

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 4 Wireless Microphone Characteristics Wireless microphones operate in locally unused TV channels; the same spectrum that WRANs will use. Operation in the U.S. is regulated by the FCC under Part 74 of the Code of Federal Regulations (47cfr74). In other countries, operation is regulated by different agencies, but with technical characteristics that are generally similar to those that apply in the U.S. Besides wireless microphones, there are wireless In Ear Monitors, IFB monitors, wireless intercoms, and wireless assist video devices (WAVDs) using the vacant TV channels.

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 5 Technical Characteristics Frequency bands: 174 – 216, 470 – 608, 614 – 806 MHz. Maximum transmitter power: 50 mW (VHF); 250 mW (UHF). Most units operate with 10 – 50 mW output. Typical antenna gain: -2 to -6 dBi. Body absorption: 5 – 15 dB. Body pack transmitters suffer much more attenuation than handheld units. Typical ERP: -6 to 0 dBm. Height Above Ground Level: 1 m.

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 6 Technical Characteristics Modulation: primarily analog FM, although other types are permitted. There are a few digital and hybrid analog/digital systems on the market. Audio frequency response: Typically 50 Hz – 15 kHz. Audio dynamic range: Typically > 100 dB. This is normally achieved through the use of analog companding. Occupied bandwidth: < 200 kHz. Most systems utilize the full bandwidth to maximize audio quality.

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 7

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 8

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 9 Propagation Characteristics United Center Tests – Chicago IL

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 10 Propagation Characteristics Handheld (dark trace) Bodypack (light trace)

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 11 Propagation Characteristics Body Pack Signals at a radius of 50 feet

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 12 Propagation Characteristics Body Pack signals at a radius of 225 feet

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 13 Propagation Characteristics Green Trace = Wireless Microphone Propagation approximates Rayleigh distribution

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 14 Received SNR vs. RF Amplitude Preferred minimum signal level

doc.: IEEE /0070r0 Submission May 2006 Edgar Reihl, Shure IncorporatedSlide 15 References IEEE Tutorial Mitigating the Effects of Unlicensed Devices on Wireless Microphones by Ahren Hartman and Edgar Reihl; presented 14 November 2005 United Center propagation data taken by Ahren Hartman and staff Receiver data taken by Garret Heath and Lakshminarayanan Thiagarajan