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US 4,060,764 AGranted
Transceiver audio system
AssigneeMotorola, Inc.
InventorsCharles William Bethards, James Edward Andrews
Life of this patent
Estimating the term…
Abstract
A compression amplifier processes both the audio modulating signal to the transmitter, and the audio output from the receiver, in a conventional amplitude modulated transceiver. Unique switching circuitry provides isolation between transmitter and receiver inputs to, and outputs from, the compression amplifier.
Claims11
A radio frequency (RF) transceiver comprising:
- a receiver portion for receiving and processing RF signals and producing an audio signal;
- a transmitter for producing a modulated RF signal, the transmitter having a modulating signal input for receiving a modulating signal and modulating an RF carrier therewith,
- the transmitter including a modulating transformer having primary and secondary windings, the primary winding adapted to receive the modulating signal and the secondary adapted for coupling to the modulating signal input of the transmitter;
- an audio compressor means for receiving and predeterminedly compressing audio signals;
- and
- switching means for switching the transceiver to either the transmit or the receive modes, the switching means comprising coupling means, operable in the transmit mode, to couple the modulating signal from the audio compressor to the primary of the modulating transformer,
- the switching means operating in the receive mode to couple the receiver produced audio signal through the audio compressor means and further including decoupling means operable in the receive mode to effectively open circuit the secondary winding of the modulating transformer, such that the transformer primary assumes a high impedance,
- whereby the audio compressor compresses both the modulating signal and the received audio signal.
5 more elements
A radio frequency (RF) transceiver comprising:
- a receiver portion for receiving and processing RF signals and producing an audio signal,
- a transmitter for producing a modulated RF signal, the transmitter having a modulating signal input for receiving a modulating signal and modulating an RF carrier therewith, said transmitter including a remotely located microphone means coupled to said transmitter via a single conductor means, said microphone including an audio preamplifier means operable when activated to amplify signals from said microphone and apply said amplified signals to said single conductor line for transmission thereover, said preamplifier means drawing a quiescent bias current from said single conductor when activated;
- an audio amplifier means for receiving and predeterminedly amplifying audio signals;
- and
- switching means for switching the transceiver to either the transmit or the receive modes, the switching means including:
- a. diode means for coupling a transceiver located bias supply to said single conductor means for supplying quiescent current to said microphone preamplifier,
- b. means for coupling one end of said diode means to said audio amplifier means,
- c. means operative in the transmit mode for
- 1. activating said microphone preamplifier means, and
- 2. for coupling the audio amplifier to the transmitter modulating signal input, and
- d. means operative in the receive mode for coupling the receiver produced audio signal to the audio amplifier means,
- whereby in the transmit mode audio signals from the microphone means are coupled through the diode means and to the audio amplifier for supplying a modulating signal to the transmitter and in the receive mode the diode means isolates the audio amplifier from the microphone and single conductor.
9 more elements
Dependencies are inferred from the claim text.