Browse Prior Art Database

SQUELCH COUPLED SELECT 5 DECODER

IP.com Disclosure Number: IPCOM000009563D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Sep-03
Document File: 1 page(s) / 73K

Publishing Venue

Motorola

Related People

Norbert Roettger: AUTHOR [+2]

Abstract

In case of voice call set-up Select 5 decoders need to vary the decoder threshold depending on the radios audio squelch setting.

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Developments Technical 0 M MOTOROLA

SQUELCH COUPLED SELECT 5 DECODER

by Norbert Roettger and Winfried Bendig

The goal for the Select 5 decoder in this special case is reliable decode in worst case SINAD (radio for Signal to Noise and Distortion - measured in dB with a 1kHz signal applied to the receiver at rated deviation) scenarios. For status information transfer the Select 5 decoder is designed for optimum noise performance and is able to decode down to 0-3dB SINAD.

  The second main application is signalling for voice call set-up. The signalling allows to selective- ly call radios out of a large group of radios listening to a channel. After the call set-up has been estab- lished, a voice communication from radio to radio follows. The radio can be configured to receive calls with an audio quality above a predefined audio level. This is normally selected by the receiver opening squelch setting. Typical values for RX squelch settings are between 12 to 20 dB SINAD . In order to adapt the Select 5 decoder for voice calls the UP / DSP based signalling decoder is automati- cally adjusted to the same sensitivity threshold as the squelch. As the UP is controlling both, the Select 5 decoder and the squelch, the threshold combina- tion can be easily achieved.

  This is done by calculating the SINAD of the received Select 5 sequence. If the incoming Select 5 sequence matches the expected decode sequence and the calculated SINAD level is above or equals to the current squelch SINAD threshold the decoder detects a valid sequence. Emergency sequences will still be detected down...