Tuning system for a high frequency receiver utilizing a controllable inductor
First Claim
1. A tuning system for a high frequency receiver comprisingat least one tunable resonance circuit the resonance frequency of which is determined by a variable inductivity element formed by a signal winding of a controllable inductor and a control winding fed by a tuning control current,an auxiliary variable frequency oscillator having an oscillating frequency determined by said control winding, said control winding being used as a frequency determinative inductance of said auxiliary variable frequency oscillator;
- and a frequency control loop connected between said auxiliary variable frequency oscillator and said resonant circuit for controlling said oscillating frequency of said auxiliary variable frequency oscillator for a predetermined constant ratio of said resonance frequency of said tunable resonance circuit to said oscillating frequency, said frequency control loop comprisingcomparing means for comparing a frequency value corresponding to said resonance frequency of said tunable resonance circuit with said oscillating frequency of said auxiliary variable frequency oscillator and generating a control signal representing the difference between said resonance and oscillating frequencies, andconverting means for converting said control signal into said control current for feeding said control winding of said controllable inductor.
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Abstract
The tuning system for a high frequency receiver, particularly an AM receiver for vehicles, comprises a tunable input resonance circuit having a variable inductance formed by the signal winding of a controllable inductor. The control winding of the inductor is supplied with a control current. The control winding is simultaneously used as the frequency determinative element of an auxiliary oscillator. A frequency control loop is used to adjust the oscillating frequency of the auxiliary oscillator by adjustment of the control current. The tuning system allows a selective coupling between the tuned antenna input circuit and the rf front end of the receiver.
30 Citations
22 Claims
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1. A tuning system for a high frequency receiver comprising
at least one tunable resonance circuit the resonance frequency of which is determined by a variable inductivity element formed by a signal winding of a controllable inductor and a control winding fed by a tuning control current, an auxiliary variable frequency oscillator having an oscillating frequency determined by said control winding, said control winding being used as a frequency determinative inductance of said auxiliary variable frequency oscillator; - and a frequency control loop connected between said auxiliary variable frequency oscillator and said resonant circuit for controlling said oscillating frequency of said auxiliary variable frequency oscillator for a predetermined constant ratio of said resonance frequency of said tunable resonance circuit to said oscillating frequency, said frequency control loop comprising
comparing means for comparing a frequency value corresponding to said resonance frequency of said tunable resonance circuit with said oscillating frequency of said auxiliary variable frequency oscillator and generating a control signal representing the difference between said resonance and oscillating frequencies, and converting means for converting said control signal into said control current for feeding said control winding of said controllable inductor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- and a frequency control loop connected between said auxiliary variable frequency oscillator and said resonant circuit for controlling said oscillating frequency of said auxiliary variable frequency oscillator for a predetermined constant ratio of said resonance frequency of said tunable resonance circuit to said oscillating frequency, said frequency control loop comprising
Specification