Browse Prior Art Database

HIGH FREQUENCY WIRELESS AUDIO LINK

IP.com Disclosure Number: IPCOM000008457D
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-17
Document File: 2 page(s) / 76K

Publishing Venue

Motorola

Related People

Matt Simms: AUTHOR

Abstract

The use of ultra-sonic transducers in communi- cations has been used before in marine applications as a method of transmission of voice and data via a liquid medium. Over medium distances, it is much more effective than its rf counterpart which is atten- uated greatly beyond a few meters at voice-band carrier frequencies. For land-based applications, transducers, when used, have been superseded by radio frequency and infrared links which accom- plish the same tasks. However, when the complexity of a communication link is a matter of concern, an ultra-sonic transducer is a clean implementation for simple needs.

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m MOTOROLA Technical Developments

HIGH FREQUENCY WIRELESS AUDIO LINK

by Matt Simms

  The use of ultra-sonic transducers in communi- cations has been used before in marine applications as a method of transmission of voice and data via a liquid medium. Over medium distances, it is much more effective than its rf counterpart which is atten- uated greatly beyond a few meters at voice-band carrier frequencies. For land-based applications, transducers, when used, have been superseded by radio frequency and infrared links which accom- plish the same tasks. However, when the complexity of a communication link is a matter of concern, an ultra-sonic transducer is a clean implementation for simple needs.

  A simple need that is evident in land mobile communications is that of a link between an ear- piece and a portable radio speaker. Often times, it is desirable to continuously monitor the output of a radio covertly and/or without disturbing others in the vicinity. For this implementation, the audio which is normally routed to the portable radio speaker is, instead, routed to a buffer which condi- tions the signal and then modulates an ultra-sonic

transducer. The modulated signal is then picked up by a matched receiving transducer and demodulated to an earpiece where the original audio is re-created. Since the nominal operating frequencies for trans- ducers are in the 40-5OKHz range, the user of the device and others in the vicinity hear nothing except what is output by the ear...