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Signal-seeking radio receivers

閱讀：921發(fā)布：2021-09-23

專利匯可以提供Signal-seeking radio receivers專利檢索，專利查詢，專利分析的服務。并且In a signal-seeking radio receiver which includes an antenna, means for automatically and sequentially tuning to a plurality of predetermined radio frequencies, and means for reproducing the intelligence therein; a tuning circuit comprising local oscillator means for generating a plurality of discrete local oscillator signals individually in sequence, and first control signal-generating means including therein a resonant circuit, having predetermined impedance vs. frequency characteristics, coupled to the local oscillator means to receive the local oscillator signals for generating a pluralitly of first control signals in response to the local oscillator signals, there being one of the aforementioned controls signals generated in response to each of the local oscillator signals. The magnitude of each control signal is proportional to the impedance of the resonant circuit at that frequency. A second control signal-generating means is coupled to the first control signal-generating means to receive the first control signals for rectifying the same and adding thereto a selected direct current threshold signal thereby producing a plurality of second control signals each of which also has a magnitude proportional to the impedance of said resonant circuit at the frequency of the local oscillator. A radio frequency amplifier is coupled between the antenna and the reproducing means, the amplifier including at least one band-pass filter having a voltage-variable reactance device therein coupled to the second control signal-generating means to receive the second control signal. The reactance of the device corresponds to the voltage applied thereto, whereby the pass-band of the filter is automatically and sequentially tuned to pass a band of frequencies about each of the predetermined frequencies in synchronism with the tuning of the receiver thereto.，下面是Signal-seeking radio receivers專利的具體信息內容。

1. For use in a signal-seeking radio receiver which includes an antenna, a receiver mixer and local oscillator means for generating a plurality of different frequency local oscillator signals automatically in seqence, thereby automatically and sequentially to tune said receiver to receive a predetermined spectrum of radio frequency signals, means for holding said receiver tuned to those signals in response to reception thereof, and means for reproducing the intelligence therein, a tuning circuit comprising: a. first control signal generating means coupled to said local oscillator means to receive said different frequency local oscillator signals for generatiNg a plurality of first control signals, there being one of said control signals generated in response to each of said local oscillator signals, said first control signal generating means including therein a resonant circuit having a predetermined impedance vs. frequency characteristic, the magnitude of each said control signal being proportional to the impedance of said resonant circuit at each of the respective frequencies of said local oscilator, said resonant circuit including means for selectively altering said characteristic thereby to selectively alter the relative magnitudes of said first control signals; b. second control signal generating means coupled to said first control signal generating means to receive said first control signals for adding thereto a signal of predetermined magnitude to produce a plurality of second control signals corresponding to said first control signals but altered in magnitude by said predetermined signal; and c. a radio frequency amplifier coupled between said antenna and said reproducing means, said amplifier including at least one tuned radio frequency circuit, said tuned circuit having a voltage-variable reactance device therein which determines the pass-band thereof coupled to said second control signal generating means to receive said second control signals, the reactance of said device corresponding to the magnitude of the signal applied thereto, whereby, the pass-band of said tuned circuit is automatically and sequentially tuned to pass a band of frequencies about each of said predetermined radio frequencies in synchronism with the tuning of said receiver thereto; said first control signals being alternating current signals, the second control signal generating means including means for rectifying said first control signals, said predetermined signal and said second control signals being direct current signals, said first control signal generating means including a first amplifier circuit having a load circuit, said resonant circuit being in said load circuit.
2. The circuit of claim 1 wherein said first control signal generating means includes a second amplifier circuit, said receiver mixer circuit being coupled to said second amplifier circuit to receive said local oscillator signals therefrom.
3. The circuit of claim 2 wherein said second amplifier circuit is coupled to said local oscillator means to receive said local oscillator signals, said control signals generated in said first amplifier circuit having frequencies equal to said local oscillator signals.
4. The circuit of claim 2 weherein said resonant circuit includes a resistor, capacitor, and inductor, the reactance of said inductor being adjustable whereby the resonant frequency of said resonant circuit may be adjusted.
5. The circuit of claim 4 wherein said first control signal generating means includes means for generating a family of alternating current signals having frequencies corresponding to respective ones of said local oscillator signals and magnitudes proportional to the impedance of said resonant circuit at the respective frequencies of said family of signals, the relative magnitude of said first control signals being changed in synchronism with adjustment of said inductor.
6. The circuit of claim 5 wherein said first amplifier circuit includes a transistor, said resonant circuit being connected in series with the collector and emitter thereof.
7. The circuit of claim 6 wherein said second control signal generating means includes a third amplifier circuit having an input and an output circuit, rectifying means including a resistor and a capacitor coupled to said third amplifier output circuit, the time constant of the last-mentioned resistor and capacitor being substantially greater than the repetition period of said local oscillator signals.
8. The circuit of claim 7 wherein said third amplifier includes biasing means for controlling the conductivity of said transistor thereof, said biasing means including a variable resistor, the magnitude of said predetermined signal being related to the selected resistance of the last-mentioned variable resistor.
9. The circuit of claim 8 wherein said resistor and capacitor of said rectifying means is in the output circuit of said third amplifier and connected together such that the discharge path for the last-mentioned capacitor is through the last-mentioned resistor.
10. The circuit of claim 9 wherein said first control signal generating means further includes a constant current generator, said mixer being coupled to said constant current generator whereby the magnitude of said local oscillator signals is substantially a constant.
11. The circuit of claim 1 wherein said voltage-variable reactance device is a voltage-variable capacitor, said tuned circuit further including an inductor, said voltage-variable capacitor being coupled to said second control signal generating means to receive said second control signals therefrom, the resonant frequency of said tuned circuit being related to the magnitude of said second control signal, the pass-band of said tuned circuit being substantially constant.
12. The circuit of claim 11 wherein said radio frequency amplifier includes a second tuned circuit, said second tuned circuit including a second voltage-variable reactance device therein and an inductor coupled to said second control signal generating means to receive said second control signals.
13. The circuit of claim 12 wherein said second voltage-variable reactance device is a voltage-variable capacitor having a capacitance related to the magnitude of a voltage applied thereto, the resonant frequency of said second tuned circuit being directly related to the magnitude of the voltage applied thereto.
14. The circuit of claim 13 wherein each said tuned circuit includes a second capacitor connected electrically in series between one terminal of said voltage-variable capacitor and one terminal of said inductor thereof, the opposite terminals of said voltage-variable capacitor and said inductor being connected to ground, said inductor including an input and an output tap adapted to receive and transmit signals, respectively.
15. The circuit of claim 1 wherein said receiver includes means for receiving radio frequency signals in at least two different radio frequency bands, said means including a radio frequency amplifier, mixer, and local oscillator means for each of said bands, said receiver further including means coupled between said antenna and said receiving means for loading said antenna for optimum reception of signals in each of said bands, said antenna loading means including means coupled to said second control signal generating means to receive said second control signals and responsive thereto for altering the tuned frequency of said antenna circuit.
16. The circuit of claim 15 wherein said antenna loading means includes a radio frequency coil and a loading coil, said loading altering means including means for shunting said loading coil in response to said second control signals.
17. The circuit of claim 16 wherein said loading means includes a diode connected electrically in shunt with said loading coil, said diode being connected to said second control signal generating means and forwardly biased by said second control signals and reverse biased in the absence thereof.
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