PHASE MEASURING SYSTEM

• US 3,764,903 A
• Filed: 08/07/1972
• Issued: 10/09/1973
• Est. Priority Date: 08/07/1972
• Status: Expired due to Term

• Current Assignee: Frederick Bethel Griswold
• Original Assignee: Frederick Bethel Griswold
• Inventors: Griswold, Frederick Bethel
• Primary Examiner(s): Smith, Alfred E.
• Application Number:
  US05/278,266
• Time in Patent Office: 428 Days
• Field of Search: 324/83R,83D
• US Class Current: 324/76.82
• CPC Class Codes: G01R 25/00 Arrangements for measuring phase angle between a voltage and a current or between voltages or currents

Abstract

A phase measuring system includes apparatus for measuring the difference in phase between a periodic input signal and a reference signal while using the same reference signal as a clock whose periods are counted as a measure of the difference in phase between the reference signal and the input signal. This is accomplished by first multiplying the phase of the input signal and then dividing its frequency and phase by a given amount and comparing this divided signal with the reference signal whose frequency and phase is also divided by the same amount. The two divided signals serve to respectively enable and disable a gate which passes the reference signal to a counter whose count manifests the phase difference between the two signals being compared.

Claims

1. In an apparatus for measuring the difference in phase between an input signal and a periodic reference thE combination comprising:

means for expanding the phase of said input signal applied thereto by a given amount, means coupled to said expanding means for altering the frequency and phase of said expanded input signal by dividing the frequency and phase of said expanded signal by said given amount for generating a first divided signal, means for altering the phase and frequency of said reference signal applied as an input thereto by dividing the frequency and phase of said reference signal by said given amount for generating a second divided signal, and phase measuring means responsive to said first and second divided signals and said reference signal applied as an input thereto for generating an output signal manifesting the difference in phase between said first and second divided signals, the difference in phase between said first and second divided signals manifesting the difference in phase between said input signal and said reference signal.

2. The combination of claim 1 wherein said phase measuring means includes:

a counter responsive to said reference signal for counting the periods of said reference applied thereto, and gating means for passing said reference signal to said counter, said gating means being enabled by said second divided signal at a given point on the waveform thereof and disabled by said first divided signal at a given point on the waveform thereof.

3. phase measuring means responsive to said first and second divided signals applied as inputs thereto for generating an output signal manifesting the difference in phase between said first and second divided signals which manifest the difference in phase between said periodic input signal and said reference signal.

4. The combination of claim 3 wherein said one multiplier includes first mixing means for mixing the divided voltage controlled oscillator output with a third signal input, and signal deriving means for deriving said third signal input from said reference signal.

5. The combination of claim 4 wherein said signal deriving means includes second mixing means for mixing the reference signal with said divided reference signal to produce said third signal input.

6. The combination of claim 3 wherein said phase measuring means includes:

a counter responsive to said reference signal for counting the periods of said reference signal applied thereto, and gating means for passing said reference signal to said counter, said gating means being enabled by said second signal input at a given point on the waveform thereof and disabled by said first signal input at a given point on the waveform thereof, the number of reference signal periods accumulated in said counter manifesting the phase angle between said first and second signal inputs.

7. In an apparatus for measuring the difference in phase between a periodic input signal having a given repetition rate and a periodic reference signal, the combination comprising:

signal deriving means responsive to said input signal for deriving as an output thereof a signal whose repetition rate is the same as that of said periodic input signal and whose phase is a multiple factor of said periodic input signal, means responsive to said derived output signal for dividing the frequency and phase of said derived output signal by an amount equal to said multiple factor for generating a first divided output signal, means for dividing by an amount equal to said multiple factor the phase and frequency of said reference signal for generating a second divided output signal such that the repetition rate thereof is the same as said first divided output signal, phase measuring means for generating an output signal manifesting the difference in phase between first and second signal inputs thereto, and input means for applying said first divided signal as said first signal input to said phase measuring means and said second divided signal as said second signal input to said phase measuring means, the difference in phase between said first and second divided signals manifesting the difference in phase between said periodic input and reference signals.

8. The combination of claim 7 wherein said signal deriving means includes, a phase detector for generating an error signal manifesting the difference in phase between a first signal input thereto and a second signal input thereto, a voltage controlled oscillator for generating as an output thereof said derived signal in response to said error signal applied as an input thereto, first mixing means for mixing said first divided signal with a third signal input thereto for providing an output signal having a phase and repetition rate substantially the same as said periodic input signal, and input means for applying said periodic signal as said first signal input and said mixing means output signal as said second signal input.

9. The combination of claim 8 further including means for generating said third signal as an output thereof including second mixing means for mixing a fourth signal input with a fifth signal input, and second input means for applying said second divided output signal as said fourth signal input and said reference signal as said fifth signal input.

10. In combination: