Browse Prior Art Database

QUICK CALL SCAN ALGORITHM

IP.com Disclosure Number: IPCOM000006552D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2002-Jan-14
Document File: 3 page(s) / 138K

Publishing Venue

Motorola

Related People

Blake Moselle: AUTHOR [+2]

Abstract

Some portable and mobile radio customers desire a way to scan for Quick Call II tones. Current scanning algorithms scan only for continuous signals such as PL/DPL or 12KHz secure. Quick call is unique because the tone duration is not continuous like PL or DPL and current algorithms do not scan for quick call tones. This new algorithm will allow scanning for these 1-6 second tones and marking of quick call channels for use as pri- ority channels.

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MOTOROLA INC. Technical Developments Volume 16 August 1992

QUICK CALL SCAN ALGORITHM by Blake Moselle and Brian Jones

  Some portable and mobile radio customers desire a way to scan for Quick Call II tones. Current scanning algorithms scan only for continuous signals such as PL/DPL or 12KHz secure. Quick call is unique because the tone duration is not continuous like PL or DPL and current algorithms do not scan for quick call tones. This new algorithm will allow scanning for these 1-6 second tones and marking of quick call channels for use as pri- ority channels.

DESCRIPTION OF INVENTION

  Some users desire to be able to scan for quick call tones on a priority or non-priority scan channel. This has not been done in the past because the current quick call decoding algorithm is required to see 800ms of tone before recognizing tone. In comparison, PL/DPL or secure can be detected in 200-300ms. When scanning for these signals, the radio will stop on each channel for 200-3OOms and look for the appropriate signal.

  To scan for quick call on a non-priority channel would require the radio to stop on the channel for at least 800ms to look for a tone. This would greatly lengthen the time required for the radio to scan its entire list. To scan for quick call on a priority channel would require the radio to leave the selected channel for at least 800ms for each priority sample. This would result in large audio holes on the selected channel.

  The way scanning and quick call currently work together is equally as bad. Radios do not scan for quick call tones, but may decode quick call tones after they have stopped on a scan channel because of proper car- rier conditions (PL/DPL, secure, etc.). To use quick call on a scan channel the base operator must send proper carrier conditions for a long enough period to insure the radio has stopped on the scan channel, then issue the quick call tones. The radio(s) for which the quick call tone is intended will decode the tones, unmute, and hear the call. The problem with this method is that, in the

meantime, any other radios with the channel in their scan list will also have stopped on the channel but will remain muted (assuming they also have quick call enabled on the channel) for the duration of the call.

  This new algorithm will allow the radio to actually scan for quick call tones without resulting in either long scan list scan times or long priority scan audio holes.

  The new algorithm will allow scanning radios to only stop on quick call channels for 200-300ms looking for a tone. If the radio does not detect the proper quick call tirst tone, it will continue to scan. However, if the radio does detect 200ms of the proper quick call first tone, it will stay on the channel until 1) it does not decode a 111 800ms of the first tone, 2) it decodes an improper sec- ond tone, 3) it loses the second tone for 500ms. If the radio decodes the entire Quick Call II tone sequence it will unmute and stay on the channel (subj...