Signal phase estimator

Claim 2

Apparatus for estimating the phase difference between a first signal and a second signal, where the second signal is of the same form and frequency as the first signal, comprising: means for producing a first correlation signal by multiplying said first and second signals; means for producing a second correlation signal by multiplying said first signal by said second signal delayed one-quarter period; means for producing a first sign signal of a given voltage amplitude to represent at any given time by its polarity the instantaneous polarity of said first correlation signal; means for producing a second sign signal of said given unit voltage amplitude to represent at any given time by its polarity the instantaneous polarity of said second correlation signal; means for multiplying said correLation signal by said second sign signal to produce a first product signal; means for multiplying said second correlation signal by said first sign signal to produce a second product signal; and means for subtracting said second product signal from said first product to derive an output signal having a value proportional to said phase difference within limits of said given unit voltage amplitude.

Claim 3

Apparatus as defined in claim 1 including apparatus for determining the sign of said phase difference, comprising: means for limiting said output signal to values below said given unit voltage amplitude to produce a limited output signal; means for multiplying said first and second sign signals to produce a third product signal; means for multiplying said second sign signal by two to produce a fourth product signal; and means for adding said fourth product signal and for subtracting said third product signal from said limited output signal, whereby the value of said limited output signal has a sign representative of the sign of said phase difference.

Claim 4

Apparatus for estimating the phase difference between a first signal and a second signal, where the second signal is of unit amplitude and of the same form and frequency as the first signal, comprising: means for correlating said first signal with a replica of said second signal to produce a first correlation signal x; means for correlating said first signal with a replica of said second signal delayed one-quarter period to produce a second correlation signal y; means for producing a first sign signal of said unit amplitude to represent at any given time by its polarity the instantaneous polarity of said first correlation signal; means for producing a second sign signal of said unit amplitude to represent at any given time by its polarity the instantaneous polarity of said second correlation signal; means for multiplying said first correlation signal by said second sign signal to produce a first product signal; means for multiplying said second correlation signal by said first sign signal to produce a second product signal; and means for subtracting said second product signal from said first product to derive an output signal having a value proportional to said phase difference within limits of said unit amplitude.

Claim 5

Apparatus for estimating the phase difference between a first signal and a second signal, where the second signal is of unit amplitude and of the same form and frequency as the first signal, comprising: means for correlating said first signal with a replica of said second signal to produce a first correlation signal x; means for correlating said first signal with a replica of said second signal delayed one-quarter period to produce a second correlation signal y; means for producing a first sign signal of said unit amplitude to represent at any given time by its polarity the instantaneous polarity of said first correlation signal; means for producing a second sign signal of said unit amplitude to represent at any given time by its polarity the instantaneous polarity of said second correlation signal; means for multiplying said first correlation signal by said second sign signal to produce a first product signal; means for multiplying said second correlation signal by said first sign signal to produce a second product signal; and means for subtracting said second product signal from said first product to derive an output signal having a value proportional to said phase difference within limits of said unit amplitude.

Claim 6

Apparatus as defined in claim 3 including apparatus for determining the sign of said phase difference, and controlling the polarity of said output signal to correspond with the sign of said phase difference, comprising: means for limiting said output signal to said unit amplitude to produce a limited output signal; means for multiplying said first and second sign signals to produce a third product signal; means for multiplying said second sign signal by two to produce a fourth product signal; and means for adding said fourth product signal and for subtracting said third product signal from said limited output signal, whereby the value of said limited output signal has a sign representative of the sign of said phase difference.

Claim 7

Apparatus for estimating the amplitude and sign of the phase difference between a first signal and a second signal, where the second signal is of unit amplitude and of the same form and frequency as the first signal, comprising: means for correlating said first signal with a replica of said second signal to produce a first correlation signal x; means for correlating said first signal with a replica of said second signal delayed one-quarter period to produce a second correlation signal y; and means for combining said first and second correlation signals according to the equation Tau T/8 2 SGN(y)-SGN(x) SGN(y)-SAT(xSGN(y)-ySGN(x)) where Tau is an estimate of the time delay of said first signal relative to said second signal producing said phasE difference, T is the period of said first and second signals, SGN(y) is the sign of the signal y, SGN(x) is the sign of the signal x and SAT(xSGN(y)-ySGN(x)) is a signal of amplitude and polarity equal to the value (xSGN(y)-ySGN(x)) limited to said unit amplitude of said second signal.

Claim 8

Apparatus for estimating the amplitude and sign of the phase difference between a first signal and a second signal, where the second signal is of unit amplitude and of the same form and frequency as the first signal, comprising: means for correlating said first signal with a replica of said second signal to produce a first correlation signal x; means for correlating said first signal with a replica of said second signal delayed one-quarter period to produce a second correlation signal y; and means for combining said first and second correlation signals according to the equation Tau T/8 2 SGN(y)-SGN(x) SGN(y)-SAT(xSGN(y)-ySGN(x)) where Tau is an estimate of the time delay of said first signal relative to said second signal producing said phasE difference, T is the period of said first and second signals, SGN(y) is the sign of the signal y, SGN(x) is the sign of the signal x and SAT(xSGN(y)-ySGN(x)) is a signal of amplitude and polarity equal to the value (xSGN(y)-ySGN(x)) limited to said unit amplitude of said second signal.

Claim 9

Apparatus as defined in claim 5 wherein said first and second correlation signals are produced according to the following equation: where z(t) is said first signal, s(t) is said replica of said second signal, s(t+(T/4)) is said replica of said second signal delayed one-quarter period, T is the period of said first and second signals, M is a multiple greater than 1 and A is a number selected to provide an amplitude of said first signal z(t) equal to unit amplitude of said replica s(t).

Claim 10

Apparatus as defined in claim 6 wherein equations for said correlation signals include a gain factor 1/A selected to provide an amplitude of said first signal equal to said unit amplitude of said second signal.