Patent ID: 6308052
Filing Date: 2001-10-23
Classification: H04B

Abstract:
A radio for a half-duplex communication system, said radio comprising:an antenna for receiving a remote signal and for transmitting a local signal, said remote signal and said local signal each including a voice signal and a beacon signal;a transceiver for providing said voice signal of said local signal; anda warning circuit connected to said antenna and said transceiver, said warning circuit including:a power splitter for receiving said remote signal from said antenna, said power splitter dividing said remote signal into said voice signal and said beacon signal and providing said voice signal of said remote signal to said transceiver;a power detector connected to said power splitter and for receiving said beacon signal, said power detector providing a DC output that is proportional to said level of said beacon signal;a comparator connected to said power detector for receiving said DC output, comparing a level of said DC output with a reference, and providing an output when said level of said DC output is greater than said reference; andan indicator for activating when said comparator provides said output;said power detector being configured so that said DC output is lower than said reference in the absence of said beacon signal and greater than said reference in the presence of said beacon signal.