RADIO FREQUENCY STANDARD AND VOLTAGE CONTROLLED OSCILLATOR

• US 3,614,630 A
• Filed: 02/04/1969
• Issued: 10/19/1971
• Est. Priority Date: 02/04/1969
• Status: Expired due to Term

• Current Assignee: Louis H. Rorden
• Original Assignee: Louis H. Rorden
• Inventors: Rorden, Louis H.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Bell, R. S.
• Application Number:
  US04/796,539
• Time in Patent Office: 987 Days
• Field of Search: 325/363,416,419,420,421,422,423 331/1,16,18,25,30,36,17 329/50,122,123,124,125,126
• US Class Current: 455/260
• CPC Class Codes: G04F 5/06 using piezoelectric resonators
• CPC Class Codes: G04R 40/02 by phase locking
• CPC Class Codes: H03B 2200/0012 Pierce oscillator
• CPC Class Codes: H03B 5/36 active element in amplifier being semiconductor device H03B5/323, H03B5/326 , H03B5/38 take precedence
• CPC Class Codes: H03L 7/081 provided with an additional controlled phase shifter H03L7/0998 takes precedence
• CPC Class Codes: H03L 7/087 using at least two phase detectors or a frequency and phase detector in the loop
• CPC Class Codes: H03L 7/14 for assuring constant frequency when supply or correction voltages fail or are interrupted

Abstract

A radio signal controlled oscillator is provided as a local frequency standard by synchronizing the oscillator using a phaselock servosystem comprising a long term integrating device as a voltage variable capacitor in the resonant circuit of the oscillator. The device consists of two columns of mercury separated by a substantial gap of electrolyte in a chamber made of dielectric material. Upon comparison of the oscillator signal with the radio signal, any error signal developed is applied across the electrolyte gap to the mercury column to transfer mercury from one to the other by the process of electrolysis. Conductive material wrapped around the chamber serves as a second plate of a capacitor for each of the columns one of which is used as part of the voltage variable capacitor. Means is provided for detecting the loss of the radio signal to interrupt any further change in the variable capacitor until the radio signal is restored.

Claims

1. A signal controlled oscillator apparatus comprising:

a radio receiver operative to develop an electrical signal;

an oscillator circuit including an active element and a turned circuit including a nonmechanical electrically variable reactance, said variable reactance being variably responsive to a first control signal and operative to cause said oscillator circuit to develop an oscillatory signal; and

a signal comparator including a phase-locked first coherent detector responsive to said electrical signal and said oscillatory signal and operative to develop said first control signal.

2. A signal controlled oscillator apparatus as defined in claim 1 wherein said signal comparator further includes a phase shifting means responsive to said first control signal and operative to modify said oscillatory signal for application to said first detector.

3. A signal controlled oscillator apparatus as defined in claim 2 wherein said phase shifting means comprises a phase shifter for shifting the phase of said oscillatory signal and a pulse generator triggered by the phase shifted oscillatory signal and operative to generate a train of pulses, said pulses being applied to said first coherent detector for causing it to sample said electrical signal.

4. A signal controlled oscillator apparatus as defined in claim 2 including a second coherent detector, means for coupling said electrical signal to said second coherent detector, 90* out of phase with the electrical signal applied to said first coherent detector, said second coherent detector also being responsive to said pulses and operative to develop a second control signal which is a maximum when said first control signal is a minimum, and a gate responsive to said second control signal and operative to couple said first control signal to said oscillator circuit only when said second control signal is present.

5. A signal controlled oscillator apparatus as defined in claim 4 and further including a threshold detector for coupling said second coherent detector to said gate whereby said second control signal enables said gate to transmit said first control signal only when said second control signal exceeds a predetermined minimum level of amplitude.

6. A signal controlled oscillator apparatus as defined in claim 1 wherein said nonmechanical electrically variable reactance comprises an elongated body of dielectric material forming an elongated chamber, a first column of metal extending from one end of said chamber toward the center thereof and a second column of metal extending from the other end of said chamber toward said center with a substantial gap between said columns, an electrolyte filling said gap, said electrolyte being suitable for electroplating the metal from one column onto the other through said gap in response to an electrical current passing therethrough, a separate electrode in ohmic contact with each of said columns, one of said electrodes extending through said body for receiving said first control signal, conductive matErial surrounding a major portion of said body form the outer end of one column to the outer end of the other column.

7. A system for providing a secondary frequency standard controlled by a radio signal, the combination comprising a radio receiver, a local oscillator, means for varying the frequency of said oscillator in response to a control signal, means for comparing the frequency of said radio signal with said oscillator frequency, said oscillator frequency being some multiple of an integer having any arbitrary value other than zero, including the value of one, and in response to said comparison, for producing a control signal proportionate to the difference between the frequency of said radio signal and said oscillator frequency divided by said integer, gating means connected to said comparing means for transmitting said control signal to said means for varying the frequency of said oscillator in response to a gating signal, means for detecting the reception of a radio signal having an amplitude above a predetermined level and in response to said detection for producing a gating signal, and means for transmitting said gating signal from said detecting means to said gating means, whereby said means for varying the frequency of said oscillator is disconnected from said comparing means when the radio signal received drops in amplitude below said predetermined level.

8. A system for providing a secondary frequency standard as defined by claim 7, wherein said means for comparing the frequency of said radio signal with said oscillator frequency comprises a first coherent detector in a phase-lock loop and said means for detecting the reception of a radio signal having an amplitude above a predetermined level comprises a second coherent detector so coupled to said receiver as to receive the radio signal 90* out of phase with the radio signal received by said first coherent detector, and a threshold level detector coupled to the output of said second coherent detector by a low-pass filter.

9. In a signal controlled oscillator including an active element and a resonant circuit having a nonmechanical electrically variable reactance element responsive to an input electrical signal, an improved reactance element comprising:

an elongated container formed of dielectric material;

a first quantity of liquid metal disposed within one portion of said container and operative to form a first capacitive electrode;

a second quantity of liquid metal disposed within another portion of said container and operative to form a second capacitive electrode;

an electrolyte disposed within said container between said first capacitive electrode and said second capacitive electrode;

a third capacitive electrode disposed exteriorly of said container and operative to cooperate with said first capacitive electrode to form a first capacitor, and with said second capacitive electrode to form a second capacitor; and

means for causing said electrical signal to flow form said first capacitive electrode through said electrolyte to said second capacitive electrode, whereby the relative capacitances of said first and second capacitors are varied as the relative sizes of first and second capacitive electrodes are changed by electrolysis.

10. A signal controlled oscillator apparatus comprising:

a radio receiver responsive to a radio signal and operative to develop an electrical signal;

an oscillator circuit including an active element and a tuned circuit including a nonmechanical electrically variable reactance, said variable reactance being responsive to a control signal and operative to provide an oscillatory signal, the frequency of which is determined by said variable reactance, said variable reactance including, an elongated container formed of dielectric material, a first quantity of liquid metal disposed within a first potion of said container and operative to form a first capacitive electrode, a second quantity of liquid metAl disposed within a second portion of said container and operative to form a second capacitive electrode, an electrolyte disposed within said container between said first capacitive electrode and said second capacitive electrode, a third capacitive electrode disposed exteriorly of said container and operative to cooperate with said first capacitive electrode to form a first capacitor, and with said second capacitive electrode to form a second capacitor, and means for coupling a control signal through said first capacitive electrode, said electrolyte, and said second capacitive electrode, whereby the relative capacitances of said first and second capacitors are varied as the relative sizes of said first and second plates are changed by electrolysis; and

a signal comparator responsive to said electrical signal and said oscillatory signal and operative to develop said control signal.

11. A signal controlled oscillator apparatus as recited in claim 10 wherein said signal comparator includes a phase-locked coherent detector.