Citizens band radio receiver with squelch control

• US 4,241,453 A
• Filed: 10/19/1978
• Issued: 12/23/1980
• Est. Priority Date: 10/19/1978
• Status: Expired due to Term

• Current Assignee: Harlan Drake
• Original Assignee: Harlan Drake
• Inventors: Drake, Harlan
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Chin, Tommy P.
• Application Number:
  US05/952,632
• Time in Patent Office: 796 Days
• Field of Search: 325/397, 325/400, 325/402, 325/403, 325/404, 325/408, 325/362, 325/473, 325/474, 325/475, 325/476, 325/478, 325/480, 325/482, 325/65, 325/348, 330/83, 330/97, 330/254, 330/259, 330/278, 330/207 P
• US Class Current: 455/219
• CPC Class Codes: H03G 3/341 Muting when no signals or only weak signals are present H03G3/344, H03G3/345 take precedence

Abstract

Tape deck adapter apparatus for radio reception, especially for reception of citizen band transmission having widely variable noise levels. The device consists of a receiver which is adaptable for use within a conventional tape deck for energization and operation; the receiver then includes an automatic squelch control circuit of the type which is particularly useful in receiving incoming citizen band transmissions. The automatic squelch control includes reactive means controlling input to the output audio amplifier, such reactance means being controlled by a DC feedback component as derived from the audio output signal, for application to control conduction of the reactance means, and therefore, the amplification of the audio output stage.

Claims

1. In combination with a radio receiver of the type adaptive for operation in an eight-track record tape deck and consisting of a receiver section providing audio frequency signal output, an audio frequency amplifier and an audio output, an automatic squelch control circuit comprising:

means receiving said audio frequency signal output to provide first input to said audio frequency amplifier;

amplifier means receiving said audio frequency signal output and generating second input to said audio frequency amplifer that is additive with said first input and in phase opposition thereto;

rectifier means receiving the output of said audio frequency amplifier to develop a D-C control signal proportional to said output; and

means applying said D-C control signal as input to said amplifier means, whereby excessive input signals to said audio frequency amplifier will proportionately reduce the amplifier means second input to said audio frequency amplifier to provide relatively greater amplitude for input thereto.

2. A circuit as set forth in claim 1 wherein said means receiving said audio frequency signal output comprises:

transistor means operated common-emitter and providing emitter output for impedance matched input to said audio frequency amplifier.

3. A circuit as set forth in claim 1 wherein said amplifier means comprises:

transistor means operated common-emitter with said audio frequency signal output applied to the base and with the collector providing said second input to said audio frequency amplifier, and with said D-C control signal also being applied to the base.

4. A circuit as set forth in claim 3 which is further characterized to include:

potentiometer means interconnected between the transistor means base input and said audio frequency signal output to adjust the input signal amplitude to said transistor means base and provide a desired amplitude balance between said first and second phase-opposed input to said audio frequency amplifier.

5. A circuit as set forth in claim 1 which further includes:

integrating means receiving said D-C control signal from said rectifier means for application to the said input of said amplifier means.

6. In combination with a radio receiver of the type adaptive for operation in an eight-track record tape deck and consisting of a receiver section providing audio frequency signal output, an audio frequency amplifier and an audio output, an automatic squelch control circuit comprising:

means receiving said audio frequency signal output to provide first input to said audio frequency amplifier;

amplifier means receiving said audio frequency signal output and generating second input to said audio frequency amplifier that is additive with said first input and in phase opposition thereto;

high gain amplifier means receiving input of said audio frequency signal output to generate a control output;

rectifier means receiving the control output from said high gain amplifier to develop a D-C control signal proportional to said output; and

means applying said D-C control signal as input to said amplifier means, whereby excessive input signals to said audio frequency amplifier will proportionately reduce the amplifier means second input to said audio frequency amplifier to provide relatively greater amplitude for input thereto.