Frequency control with a phase-locked-loop

Claim 2

A frequency control system for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; an alternating signal source for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said alternating signal and said phase-shifted external signal which comprises means for biasing out the phase-shift due to transit time delays of said external signal; and means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 3

A frequency control system for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; an alternating signal source for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said alternating signal and said phase-shifted external signal; means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; and means responsive to said phase-shifted external signal for demodulating amplitude variations carried by said external signal; said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 4

A frequency control system for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; an alternating signal source for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said alternating signal and said phase-shifted external signal; means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; and means responsive to said phase-shifted external signal for demodulating amplitude variations carried by said external signal; said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 5

A frequency control system for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal comprising a bandpass filter having a passband covering a range of frequencies including frequency, f o , and variations thereof, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; an alternating signal source, comprising a voltage controlled oscillator, for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said alternating signal and said phase-shifted external signal comprising a phase detector having means for biasing out the phase-shift due to transit time delays of said external signal; and means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 6

A frequency control system for automatically adjusting the frequency of an alternating signal and an external signal derived coherently therefrom to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal comprising a bandpass filter having a passband covering a range of frequencies including frequency, f o , and variations thereof, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; an alternating signal source, comprising a voltage controlled oscillator, for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said alternating signal and said phase-shifted external signal comprising a phase detector having means for biasing out the phase-shift due to transit time delays of said external signal; and means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 7

The frequency control system according to claim 3, in which said means for converting said phase-difference signal comprises a signal integrator.

Claim 8

The frequency control system according to claim 4, further comprising means for remotely impressing amplitude variations upon said external signal.

Claim 9

The frequency control system according to claim 5, further comprising means responsive to said phase-shifted external signal for demodulating amplitude variations carried by said external signal.

Claim 10

A feedback frequency control system for adjusting the frequency of an alternating signal and an external signal, derived coherently therefrom and determinably time-delayed relative thereto, to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; further phase-shift means responsive to said alternating signal for biasing out phase-shifts resulting from determinable propagation transit time delay of said external signal to produce a phase-biased alternating signal; an alternating signal source for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said phase-biased alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said phase-biased alternating signal and said phase-shifted external signal; and means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; said further phase-shift means adjusted to bias out the phase-shift due to said determinable propagation transit time delay of said external signal; and said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said phase-biased alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 11

A feedback frequency control system for adjusting the frequency of an alternating signal and an external signal, derived coherently therefrom and determinably time-delayed relative thereto, to the drift-prone zero phase-shift frequency of phase-shift means adapted to receive said external signal, said control system comprising: phase-shift means responsive to said external signal for introducing a frequency sensitive bipolar phase-shift to said external signal to produce a phase-shifted external signal, said phase-shift means introducing zero phase-shift at drift-prone frequency, f o ; further phase-shift means responsive to said alternating signal for biasing out phase-shifts resulting from determinable propagation transit time delay of said external signal to produce a phase-biased alternating signal; an alternating signal source for generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; means responsive to both said phase-biased alternating signal and said phase-shifted external signal for producing a phase-difference signal corresponding to the difference in phase between said phase-biased alternating signal and said phase-shifted external signal; and means responsive to said phase-difference signal for converting said phase-difference signal to a frequency control signal; said further phase-shift means adjusted to bias out the phase-shift due to said determinable propagation transit time delay of said external signal; and said alternating signal source being responsive to said frequency control signal to minimize the difference in phase between said phase-biased alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to frequency, f o .

Claim 12

Method for adjusting the frequency of an alternating signal and an external signal, derived coherently therefrom and determinably propagation transit time-delayed relative thereto, to the drift-prone frequency, f o , corresponding to zero phase-shift through a phase-shifter adapted to receive said external signal, said method comprising the steps of: biasing out the phase-shifting effects of the determinable propagation transit time-delay of said external signal; shifting the phase of said external signal in accordance with the deviation in frequency from said drift-prone frequency, f o , of said phase-shifter to produce a phase-shifted external signal; generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; producing a phase-difference signal corresponding to a difference in phase between said alternating signal and said phase-shifted external signal; converting said phase-difference signal to a frequency control signal; and causing said alternating signal to respond to said frequency control signal to minimize said difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to said drift-prone frequency, f o .

Claim 13

Method for adjusting the frequency of an alternating signal and an external signal, derived coherently therefrom and determinably propagation transit time-delayed relative thereto, to the drift-prone frequency, f o , corresponding to zero phase-shift through a phase-shifter adapted to receive said external signal, said method comprising the steps of: biasing out the phase-shifting effects of the determinable propagation transit time-delay of said external signal; shifting the phase of said external signal in accordance with the deviation in frequency from said drift-prone frequency, f o , of said phase-shifter to produce a phase-shifted external signal; generating said alternating signal of adjustable frequency covering a range of frequencies including frequency, f o , and variations thereof; producing a phase-difference signal corresponding to a difference in phase between said alternating signal and said phase-shifted external signal; converting said phase-difference signal to a frequency control signal; and causing said alternating signal to respond to said frequency control signal to minimize said difference in phase between said alternating signal and said phase-shifted external signal whereby said alternating signal frequency is adjusted to be substantially equal to said drift-prone frequency, f o .