System responsive to change of phase between two electrical waves

Claim 2

A phase measuring circuit adapted to measure the phase difference between a reference signal and a signal to be measured, comprising in combination a source of a comparison signal locked in frequency to the frequency of the reference signal and to the frequency of the signal to be measured, filtering means to pass a fundamental wave of the common frequency of all three signals, zero-detection means responsive to the zero crossing of an applied wave and adapted to provide an output signal when said applied wave passes through a zero crossing, counting means which can be switched to either an adding or a subtracting mode, a source of counting pulses of a repetition frequency which is higher than the common frequency and having a fixed frequency relationship thereto, gating means to control the application of the counting pulses to the counter, and sequential control and switching means which program a measuring sequence in which said filtering means and zerodetection means are time-shared by the reference signal and the signal to be measured, and wherein a first counting regime with the counter in the adding mode provides a counter content representative of the phase difference between the comparison signal and the reference signal, and a second counting regime with the counter in the subtracting mode wherein the counter when counting in the opposite direction provides an opposite count to an extent representative of the phase difference between the comparison signal and the signal to be measured, and whereby the final counter content is representative of the phase difference between the reference signal and the signal to be measured.

Claim 3

A phase measuring circuit as claimed in claim 1 wherein the measuring sequence is automatically and continually recycled.

Claim 4

A phase measuring circuit as claimed in claim 1, wherein the source of counting pulses is a controllable source the nominal frequency of which is an integral multiple of the reference frequency, and forms part of a frequency-lock loop including a frequency comparator, the output of which comparator controls the output frequency of the controllable source, a first input to the frequency comparator consisting of the reference frequency and a second input thereto being derived from the output of the controllable source through a frequency divider having a divider ratio corresponding to the aforesaid integral multiple.

Claim 5

A phase measuring circuit as claimed in claim 1, further comprising means for initiating said first and second counting regimes at an arbitrarily chosen point on the wave form of said comparison signal and means for terminating said first and second counting machines at zero-crossings of said reference signal and said signal to be measured respectively.

Claim 6

A phase measuring circuit as claimed in claim 1, further comprising indicator means for displaying the phase difference between said reference signal and said signal to be measured.

Claim 7

A phase monitoring circuit adapted to monitor the phase difference between a reference signal and a signal to be monitored, comprising in combination a source of a comparison signal locked in frequency to the frequency of the reference signal and to the frequency of the signal to be monitored, filtering means to pass a fundamental wave Of the common frequency of all three signals, zero-detection means responsive to zero crossing of an applied wave and adapted to provide an output signal when said applied wave passes through a zero crossing, counting means which can be switched to either an adding or a subtracting mode, a source of counting pulses of a repetition frequency which is higher than the common frequency, gating means to control the application of the counting pulses to the counter, sequential control and switching means which program a measuring sequence in which said filtering means and zero-detection means are time-shared by the reference signal and the signal to be monitored, and means giving a characteristic indication when the phase difference between the reference signal and the signal to be monitored attains a predetermined value, and wherein a first counting regime with the counter in the adding mode provides a counter content representative of the phase difference between the comparison signal and the reference signal, and a second counting regime with the counter in the subtracting mode wherein the counter when counting in the opposite direction provides an opposite count to an extent representative of the phase difference between the comparison signal and the signal to be monitored, and whereby the final counter content is representative of the phase difference between the reference signal and the signal to be monitored.

Claim 8

A phase monitoring circuit adapted to monitor the phase difference between a reference signal and a signal to be monitored, comprising in combination a source of a comparison signal locked in frequency to the frequency of the reference signal and to the frequency of the signal to be monitored, filtering means to pass a fundamental wave Of the common frequency of all three signals, zero-detection means responsive to zero crossing of an applied wave and adapted to provide an output signal when said applied wave passes through a zero crossing, counting means which can be switched to either an adding or a subtracting mode, a source of counting pulses of a repetition frequency which is higher than the common frequency, gating means to control the application of the counting pulses to the counter, sequential control and switching means which program a measuring sequence in which said filtering means and zero-detection means are time-shared by the reference signal and the signal to be monitored, and means giving a characteristic indication when the phase difference between the reference signal and the signal to be monitored attains a predetermined value, and wherein a first counting regime with the counter in the adding mode provides a counter content representative of the phase difference between the comparison signal and the reference signal, and a second counting regime with the counter in the subtracting mode wherein the counter when counting in the opposite direction provides an opposite count to an extent representative of the phase difference between the comparison signal and the signal to be monitored, and whereby the final counter content is representative of the phase difference between the reference signal and the signal to be monitored.

Claim 9

A time-shared zero-crossing method of phase measurement comprising the steps of: placing a binary counter in an adding mode; measuring a first phase difference between a reference signal and a arbitrarily phased frequency-locked comparison signal; placing said counter in a subtracting mode; measuring a second phase difference between a signal to be measured and said comparison signal; obtaining a phase difference between said first and second phase difference measurements; displaying the phase difference between said reference signal and said signal to be measured; and continuously repeating the sequence of said measurements.

Claim 10

A time-shared zero-crossing method of phase measurement comprising the steps of: placing a binary counter in an adding mode; measuring a first phase difference between a reference signal and a arbitrarily phased frequency-locked comparison signal; placing said counter in a subtracting mode; measuring a second phase difference between a signal to be measured and said comparison signal; obtaining a phase difference between said first and second phase difference measurements; displaying the phase difference between said reference signal and said signal to be measured; and continuously repeating the sequence of said measurements.

Claim 11

A time-shared zero-crossing method of phase measurement as claimed in claim 7, comprising the further step of determining the period of said measurements by means of a source of counting pulses having a repetition frequency higher than the frequency of said reference signal.

Claim 12

A time-shared zero-crossing method of phase monitoring comprising the steps of: placing a binary counter in an adding mode; measuring a first phase difference between a reference signal and an arbitrarily phased frequency-locked comparison signal; placing said counter in a subtracting mode; measuring a second phase difference between a signal to be monitored and said comparison signal; obtaining a phase difference between said first and second phase difference measurements; displaying the phase difference between said reference signal and said signal to be monitored; obtaining a characteristic indication when the phase difference between said reference signal and said signal to be monitored exceeds a predetermined value; and continuously repeating the sequence of said measurements.

Claim 13

A time-shared zero-crossing method of phase monitoring comprising the steps of: placing a binary counter in an adding mode; measuring a first phase difference between a reference signal and an arbitrarily phased frequency-locked comparison signal; placing said counter in a subtracting mode; measuring a second phase difference between a signal to be monitored and said comparison signal; obtaining a phase difference between said first and second phase difference measurements; displaying the phase difference between said reference signal and said signal to be monitored; obtaining a characteristic indication when the phase difference between said reference signal and said signal to be monitored exceeds a predetermined value; and continuously repeating the sequence of said measurements.