Automatic phase and frequency control system

Claim 2

An automatic phase and frequency control system for producing phase and frequency synchronism between a locally generated signal and an input signal comprising: oscillator means producing an oscillatory signal having a frequency responsive to a control signal; generating means producing first and second beat signals between said input signals and said oscillatory signal, said beat signals having a substantially quadrature relationship; translating means converting said first beat signal to a constant amplitude signal having a phase relative to said second beat signal which varies in a predetermined relationship to said beat signal frequency, said translating means being capable of coupling a D.C. signal; first multiplying means multiplying said second beat signal and the output signal of said translating means to develop a control signal, said second beat signal being applied to said multiplying means such that the relative amplitude of said output signal of said translating means and said second beat signal remain substantially constant and the relative phase therebetween varies as a function of beat signal frequency; and first filter means coupling said control signal to said oscillator means.

Claim 3

An automatic phase and frequency control system as set forth in claim 1 wherein said translating means includes: second filter means, including a low-pass filter, coupled to said generating means, producing a phase shift in signals coupled therethrough which has a predetermined relationship to signal frequency,.

Claim 4

An automatic phase and frequency control system as set forth in claim 2 wherein said translating means includes: limiting means, coupled to said second filter means and said first multiplying means, producing symmetrical amplitude limiting of said first beat signal.

Claim 5

An automatic phase and frequency control system as set forth in claim 3 wherein said generating means include: second and third multiplying means each responsive to said output signal of said oscillator means and said input signal; means coupling in-phase samples of said input signal to said second and third multiplying means; and quadrature means coupling quadrature phased samples of said oscillator means output signal to said second and third multiplying means.

Claim 6

An automatic phase and frequency control system as set forth in claim 4 wherein said quadrature means include: a 90° phase shift network interposed between said third multiplying means and said oscillator means.

Claim 7

An automatic phase and frequency control system as set forth in claim 3 wherein said generating means include: second and third multiplying means each responsive to said output signal of said oscillator means and said input signal; quadrature means coupling quadrature phased samples of said input signal to said second and third multiplying means; and means coupling in-phase samples of said oscillator means output signal to said second and third multiplying means.

Claim 8

An automatic phase and frequency control system as set forth in claim 6 wherein said quadrature means include: a 90° phase shift network coupling said input signal to said second multiplying means.

Claim 9

An automatic phase and frequency control system for maintaining phase and frequency synchronism between a locally generated signal and an input signal: a voltage controlled oscillator producing an oscillatory signal having a frequency determined by an applied control signal; a first and a second multiplier each producing an output signal equal to the product of two input signals; means coupling the output signal of said voltage controlled oscillator and said input signal to the respective inputs of said first and second multipliers such that the output signals of said first and second multipliers are in quadrature; a first low pass filter, coupled to the output of said second multiplier having a predetermined phase delay characteristic producing a phase shift which varies as a function of signal frequency; a limiter, coupled to said first low pass filter, symmetrically limiting the amplitude of the output signal of said first low pass filter; a third multiplier, responsive to the output signals of said limiter and said first multiplier, producing an output signal equal to the product thereof, the output signal of said first multiplier being applied to said third multiplier such that the relative amplitudes of said output signals of said limiter and said first multiplier remain substantially constant and the relative phase therebetween varies as a function of beat signal frequency; and a second low pass filter coupling the output signal of said third multiplier to the control signal input of said voltage controlled oscillator.

Claim 10

An automatic phase and frequency control system for maintaining phase and frequency synchronism between a locally generated signal and an input signal: a voltage controlled oscillator producing an oscillatory signal having a frequency determined by an applied control signal; a first and a second multiplier each producing an output signal equal to the product of two input signals; means coupling the output signal of said voltage controlled oscillator and said input signal to the respective inputs of said first and second multipliers such that the output signals of said first and second multipliers are in quadrature; a first low pass filter, coupled to the output of said second multiplier having a predetermined phase delay characteristic producing a phase shift which varies as a function of signal frequency; a limiter, coupled to said first low pass filter, symmetrically limiting the amplitude of the output signal of said first low pass filter; a third multiplier, responsive to the output signals of said limiter and said first multiplier, producing an output signal equal to the product thereof, the output signal of said first multiplier being applied to said third multiplier such that the relative amplitudes of said output signals of said limiter and said first multiplier remain substantially constant and the relative phase therebetween varies as a function of beat signal frequency; and a second low pass filter coupling the output signal of said third multiplier to the control signal input of said voltage controlled oscillator.