Dual threshold repeater squelch circuit
AssigneeMotorola, Inc.
InventorsRalph W. Andrea, III, Leonard W. Bennett, William W. O'Connor
Life of this patent
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Abstract
In a mobile repeater system there can be two priority repeaters at two adjacent locations which are out of range of each other, but not out of range of each other's portable units. Reception of a tone coded signal from a portable raises the squelch threshold in both repeaters, thus decreasing the portable-to-repeater range without decreasing the repeater-to-repeater range. Interferences caused by simultaneous transmission is eliminated since only the appropriate repeater is activated.
Claims7
A dual threshold squelch control circuit for use with received signals which may contain a coded tone in addition to the intelligence signals for controlling a receiver squelch circuit, the control circuit comprising in combination:
- first detector means responsive to the reception of a usable carrier signal;
- second detector means responsive to the reception of a predetermined coded tone on said received signal;
- low frequency amplifying means;
- first circuit means for coupling an output signal of the first detector means to a signal input of the amplifier means;
- switching means for controlling the amplitude of the output signal of the amplifying means;
- second circuit means for coupling an output signal of the second detector means to the switching means for enabling said switching means when the coded tone is detected;
- and
- third circuit means for coupling the controlled output of the amplifying means to the squelch circuit for enabling said squelch circuit.
Dependencies are inferred from the claim text.