Browse Prior Art Database

Simulcast System Receiver Capture Ratio Improvement

IP.com Disclosure Number: IPCOM000049616D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Heins, DE: AUTHOR

Abstract

Briefly, this article describes a simulcast radio system in which the radiated power at selected transmitters is reduced on message retries to give a receiver a better opportunity to acquire a single strong signal.

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Simulcast System Receiver Capture Ratio Improvement

Briefly, this article describes a simulcast radio system in which the radiated power at selected transmitters is reduced on message retries to give a receiver a better opportunity to acquire a single strong signal.

In a simulcast system, several widely spaced transmitters transmit the same signal simultaneously. Such a system is used to provide wide area coverage for mobile receivers. The individual transmitter sites are under the control of a central controller.

A receiver that detects signals from two or more transmitters may not be able to reject all but the strongest signal. For example, see Fig. 1 where the circles represent the areas covered by transmitters T1 through T4. A receiver located at the indicated point would receive signals radiated by transmitters T1 and T4.

If the receiver is not able to reject all but the strongest signal, it can declare an error condition and request a retry. The radiated power at selected transmitters is then reduced. While the receiver might still acquire signals from both transmitters, one signal would be relatively stronger than the other The receiver would be better able to reject all but the strongest signal, that is, to operate within its capture ratio capability.

A retry simulcast transmission is illustrated in Fig. 2. The radiated power from transmitters T2 and T4 is reduced on retries. The coverage afforded by those transmitter sites is reduced from the original ar...