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DYNAMIC RECEIVER FREQUENCY STEERING IN WIDE AREA SYSTEMS

IP.com Disclosure Number: IPCOM000006969D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2002-Feb-13
Document File: 3 page(s) / 141K

Publishing Venue

Motorola

Related People

Iain James Hamilton: AUTHOR

Abstract

AMSS TRUNKING WITH RECEIVER VOTING In 800 MHZ AMSS trunking systems, there is no receiver voting. When a portable transmits on a voice channel, only one receiver is tuned to that frequency, The DIGITAC votes the best signal from a choice of one site, even ifthe signal is not ideal.

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MOTOROLA INC. Technical Developments Volume 19 June 1993

DYNAMIC RECEIVER FREQUENCY STEERING IN WIDE AREA SYSTEMS

by lain James Hamilton

AMSS TRUNKING WITH RECEIVER VOTING

  In 800 MHZ AMSS trunking systems, there is no receiver voting. When a portable transmits on a voice channel, only one receiver is tuned to that frequency, The DIGITAC votes the best signal from a choice of one site, even ifthe signal is not ideal.

For each channel wide area channel a maximum of one receiver is used at one time.

  In AMSS with receiver steering, a receiver at each site is tuned to the frequency of the transmitting porta- ble for the duration of that portable's transmission. This allows the voter to choose the best site, as with conven- tional voting.

When the portable dekeys, all receivers revert to their home frequencies.

IMPLE'MENTATION

  Receiver steering only requires two elements to implement: dynamically tunable repeater and receiver steering controller.

  The MSF 5000 already has multiple thequency capa- bility and can be retuned dynamically several ways. The simplest is tone remote. The standard trunked repeater requires programming with one channel per site in the system. For a three-site AMSS system, each repeater has three channels. One is the home channel and uses the frequencies it does for standard AMSS. The other two channels have the same transmit frequency as the home channel, but the receive frequencies are the same the home channels for the corresponding repeaters at the other two sites.

  Under idle conditions all receivers default to their home channels. A portable radio is granted a voice chan- nel in the normal way, and transmits on a voice channel. A receiver unsquelches at one site, and the DIGITAC gates the audio to the repeat path and to the console.

B Motorola. Inc. ,993

  The receiver steering controller would be a new prod- uct. When the digitac votes, two lies become active low: the "Vote" and the "vote indicate" for the site that unsquelches. The Receiver steering controller sends out a tone sequence followed by LLGT The tones sent cor- respond to the site that unsquelches. LLGT is active as long as the Vote for the whole wide area channel is active.

  The tone sequence and LLGT are routed to repeat- ers at each site. At the site which ftrst received the trans- mission transmit audio is gated to the transmitter in the normal way. The receiver does not retune.

  At the other two sites the tone sequence sent from the receiver steering controller commands the repeaters to retune. Their transmit frequencies are unchanged, and the transmitters operate exactly as conventional AMSS, broadcasting the transmission. The receivers retune to the frequency of the receiver t...