Browse Prior Art Database

TRUNKED COMMUNICATIONS LOGGING FROM FIXED INFRASTRUCTURE SYSTEM COMPONENTS WITH POST-CALL DETRUNKING

IP.com Disclosure Number: IPCOM000007971D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-09
Document File: 2 page(s) / 114K

Publishing Venue

Motorola

Related People

Jeffrey G. Lohrbach: AUTHOR [+3]

Abstract

Call logging in trunked communications sys- tems is generally accomplished with modified dis- patch consoles or through the use of fixed-frequen- cy receivers (control stations). When using the modified dispatch equipment approach, the audio is detrunked prior to recording. Audio for each talk- group is on separate recorder tracks. When using the control stations approach, the over-the-air audio is captured while another device simultaneously captures the system call data. The call data is recorded simultaneously with the audio, allowing later retrieval of the call audio based on that call data.

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MO-LA Technical Developments

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TRUNKED COMMUNICATIONS LOGGING FROM FIXED INFRASTRUCTURE SYSTEM COMPONENTS WITH POST-CALL DETRUNKING

by Jeffrey G. Lohrbach, James M. Connor, and John M. Gilbert

BACKGROUND

  Call logging in trunked communications sys- tems is generally accomplished with modified dis- patch consoles or through the use of fixed-frequen- cy receivers (control stations). When using the modified dispatch equipment approach, the audio is detrunked prior to recording. Audio for each talk- group is on separate recorder tracks. When using the control stations approach, the over-the-air audio is captured while another device simultaneously captures the system call data. The call data is recorded simultaneously with the audio, allowing later retrieval of the call audio based on that call data.

  These existing methods become increasingly expensive and cumbersome as system size grows. Using modified dispatch equipment is expensive when the number of talkgroups is large. Using con- trol stations is expensive as the number of system repeaters is large.

  Large, multi-site systems, in particular, require an economical means of logging trunked audio because such systems generally have high numbers of both repeaters and talkgroups.

DESCRIPTION

  Logging from fixed infrastructure system com- ponents differs from modified dispatch logging in that detrunking is accomplished on playback, not prior to or simultaneous with the recording of the audio. In Motorola SmartZone systems, the call data used for detrunking is acquired from the fixed

infrastructure in the form of the ATIA (Air Traffic Information Access) message stream.

  Infrastructure based logging differs from control station-based logging in that audio is obtained from infrastructure audio taps. In Motorola SmartZone systems, the audio taps can be located at the digital Tl/El links connecting the SmartZone audio switch with decryption/voice coding equipment. Audio from these taps is fed into the digital recorder, where the audio is tagged with time information and recorded. A similar "tap" could be used with ana- log-only calls. This would require the audio switch to send audio for the analog-only calls out this path to the logging recorder.

  The system's call data stream is also fed into the digital recorder and saved with corresponding time information. In addition to talkgroup I...