Browse Prior Art Database

ASTRO SIMULCAST DATA BANKING

IP.com Disclosure Number: IPCOM000009578D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Sep-04
Document File: 2 page(s) / 94K

Publishing Venue

Motorola

Related People

Michael Petrie: AUTHOR [+2]

Abstract

Astro Simulcast systems provide good RF cov- erage in site overlap areas by ensuring that the sig- nals being transmitted from each site are identical. When the infrastructure link to one of these sites experiences a temporary interruption, the resulting signal being transmitted from this site will be cor- rupted resulting in a loss of audio in all areas cov- ered by this site, including areas overlapping with adjacent sites. This publication will present a solu- tion that will avoid the signal corruption in overlap- ping areas.

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Technical MO-LA @ Developments

ASTRO SIMULCAST DATA BANKING

by Michael Petrie and Joseph Lukose

ABSTRACT

  Astro Simulcast systems provide good RF cov- erage in site overlap areas by ensuring that the sig- nals being transmitted from each site are identical. When the infrastructure link to one of these sites experiences a temporary interruption, the resulting signal being transmitted from this site will be cor- rupted resulting in a loss of audio in all areas cov- ered by this site, including areas overlapping with adjacent sites. This publication will present a solu- tion that will avoid the signal corruption in overlap- ping areas.

BACKGROUND

  In current Astro Simulcast Systems, the Base Station fabricates a substitute "canned" transmit data frame when the actual data frame is missing due to a CRC failure over the link supplying trans- mit data to the station. This is done to maintain transmit bit synchronization at the station during this period so that subsequent good data frames will be transmitted in synch with the other sites. The canned transmit data from this site will interfere with the signals from adjacent sites resulting in unnecessary audio dropouts heard at the subscriber units in these overlap areas.

SOLUTION

  The APCO Linear Simulcast Station provides the capability to perform a controlled dekey and rekey of the station transmitter as part of its lin- earization process. This function can be utilized to dekey and rekey the station during the preceding

and subsequent FUNID interval in which a fab- ricated data frame would otherwise have to be transmitted.

  The Linear Simulcast Station can use this method to refrain from transmitting the fabricated data frame thus preventing interference in the over- lap areas. The receiving subscribers in the capture area of the problem transmitter site will obviously lose the fabricated data. More importantly, howev- er, they will not lose carrier detect since the sensitiv- ity of the car...