Demodulating method and apparatus

Claim 1

A method for determining the phase relationship between an AC input signal and an AC reference signal which are constrained to be either of the same phase of the AC input signal, the method comprising the steps of: converting the AC input signal into a half-wave rectified DC signal having one polarity when the AC input signal is in phase with the AC reference signal and having the opposite polarity when the AC input signal is out of phase with the AC reference signal; decreasing the amplitude of the AC input signal so as to obtain a reduced amplitude AC signal; subtracting the reduced amplitude AC signal from the half-wave rectified DC signal to obtain a full-wave rectified DC signal having the same polarity as the half-wave rectified DC signal; and averaging the amplitude of the full-wave rectified DC signal to obtain a DC output signal having a polarity which is indicative of the phase relationship between the AC input signal and the AC reference signal and having an amplitude which is indicative of the amplitude of the AC input signal.

Claim 2

A method for determining the phase relationship between an AC input signal and an AC reference signal which are constrained to be either of the same phase of the AC input signal, the method comprising the steps of: converting the AC input signal into a half-wave rectified DC signal having one polarity when the AC input signal is in phase with the AC reference signal and having the opposite polarity when the AC input signal is out of phase with the AC reference signal; decreasing the amplitude of the AC input signal so as to obtain a reduced amplitude AC signal; subtracting the reduced amplitude AC signal from the half-wave rectified DC signal to obtain a full-wave rectified DC signal having the same polarity as the half-wave rectified DC signal; and averaging the amplitude of the full-wave rectified DC signal to obtain a DC output signal having a polarity which is indicative of the phase relationship between the AC input signal and the AC reference signal and having an amplitude which is indicative of the amplitude of the AC input signal.

Claim 3

A method for determining the direction and the magnitude of the displacement of a movable member from a null position, the method comprising the steps of: producing an AC input signal having one phase when the movable member is displaced in one direction from the null position and having the opposite phase when the movable member is displaced in the opposite direction from the null position, the AC input signal further having an amplitude which is a function of the magnitude of the displacement of the movable member from the null position; producing an AC reference signal having a frequency which is identical to the frequency of the AC input signal; and having a phase which is the same as one phase of the AC input signal and opposite to the other phase of the AC input signal; rectifying the AC input signal in response to the AC referernc signal to obtain a half-wave rectified DC signal having one polarity when the AC input signal and the AC reference signal are are of the same phase and having opposite polarity when the AC input signal and the AC reference signal are of the opposite phase; decreasing the amplitude of the AC input signal to obtain a reduced amplitude AC signal; adding the half-wave rectified DC signal and the reciprocal of the reduced amplitude AC signal to obtain a full-wave rectified DC signal having the same polarity as the half-wave rectified DC signal; and averaging the amplitude of the full-wave rectified DC signal to obtain a DC output signal having a polarity which indicates the direction of the displacement of the movable member from the null position and having an amplitude which indicates the magnitude of the displacement of the movable member from the null position.

Claim 4

A method for determining the direction and the magnitude of the displacement of a movable member from a null position, the method comprising the steps of: producing an AC input signal having one phase when the movable member is displaced in one direction from the null position and having the opposite phase when the movable member is displaced in the opposite direction from the null position, the AC input signal further having an amplitude which is a function of the magnitude of the displacement of the movable member from the null position; producing an AC reference signal having a frequency which is identical to the frequency of the AC input signal; and having a phase which is the same as one phase of the AC input signal and opposite to the other phase of the AC input signal; rectifying the AC input signal in response to the AC referernc signal to obtain a half-wave rectified DC signal having one polarity when the AC input signal and the AC reference signal are are of the same phase and having opposite polarity when the AC input signal and the AC reference signal are of the opposite phase; decreasing the amplitude of the AC input signal to obtain a reduced amplitude AC signal; adding the half-wave rectified DC signal and the reciprocal of the reduced amplitude AC signal to obtain a full-wave rectified DC signal having the same polarity as the half-wave rectified DC signal; and averaging the amplitude of the full-wave rectified DC signal to obtain a DC output signal having a polarity which indicates the direction of the displacement of the movable member from the null position and having an amplitude which indicates the magnitude of the displacement of the movable member from the null position.

Claim 5

An apparatus for indicating the phase relationship between an AC input signal and an AC reference signal which are constrained to be either of the same phase or of the opposite phase and for indicating the amplitude of the AC input signal, the apparatus comprising: switching means connected to receive the AC input signal and the AC reference signal for rectifying the AC input signal in response to the AC reference signal to obtain a half-wave rectified DC signal having one polarity when the AC input signal and the AC reference Signal are of the same phase and having the opposite polarity when the AC input signal and the AC reference signal are of the opposite phase; attenuating means connected to receive the AC input signal for decreasing the amplitude of the AC input signal to obtain a reduced amplitude AC signal; differencing means connected to the switching means and to the attenuating means for subtracting the reduced amplitude AC signal from the half-wave rectified DC signal to obtain a DC output signal having a polarity which is indicative of the phase relationship between the AC input signal and the AC reference signal and having an amplitude which is indicative of the amplitude of the AC input signal.

Claim 6

An apparatus for indicating the phase relationship between an AC input signal and an AC reference signal which are constrained to be either of the same phase or of the opposite phase and for indicating the amplitude of the AC input signal, the apparatus comprising: switching means connected to receive the AC input signal and the AC reference signal for rectifying the AC input signal in response to the AC reference signal to obtain a half-wave rectified DC signal having one polarity when the AC input signal and the AC reference Signal are of the same phase and having the opposite polarity when the AC input signal and the AC reference signal are of the opposite phase; attenuating means connected to receive the AC input signal for decreasing the amplitude of the AC input signal to obtain a reduced amplitude AC signal; differencing means connected to the switching means and to the attenuating means for subtracting the reduced amplitude AC signal from the half-wave rectified DC signal to obtain a DC output signal having a polarity which is indicative of the phase relationship between the AC input signal and the AC reference signal and having an amplitude which is indicative of the amplitude of the AC input signal.

Claim 7

An apparatus for determining the direction and the magnitude of the displacement of a movable member from a null position, the apparatus comprising: position sensor means mechanically connected with the movable member for providing an AC input signal having one phase when the movable member is displaced in one direction from the null position and having the opposite phase when the movable member is displaced in the opposite direction from the null position, the AC input signal further having an amplitude which is a function of the magnitude of the displacement of the movable member from the null position; signal generator means for producing an AC reference signal having a frequency which is identical to the frequency of the AC input signal and having a phase which is the same as one phase of the AC input signal and opposite to the other phase of the AC input signal; chopper means connected to the position sensor means and to the signal generator means for rectifying the AC input signal in response to the AC reference signal to obtain a half-wave rectified DC signal having one polarity when the AC input signal and the AC reference signal are of the same phase and having the opposite polarity when the AC input signal and the AC reference signal are of opposite phase; attenuator means connected to the position sensor means for decreasing the amplitude of the AC input signal to obtain a reduced amplitude AC signal; differencer means connected to the chopper means and to the attenuator means for inverting the reduced amplitude AC signal and adding it with the half-wave rectified DC signal to obtain a full-wave rectified DC signal having the same polarity as the half-wave rectified DC signal; and filter means connected to the differencer means for averaging the amplitude of the full-wave rectified DC signal to obtain a DC output signal having a polarity which indicates the direction of the displacement of the movable member from the null position and having an amplitude which indicates the magnitude of the displacement of the movable member from the null position.

Claim 8

An apparatus for determining the direction and the magnitude of the displacement of a movable member from a null position, the apparatus comprising: position sensor means mechanically connected with the movable member for providing an AC input signal having one phase when the movable member is displaced in one direction from the null position and having the opposite phase when the movable member is displaced in the opposite direction from the null position, the AC input signal further having an amplitude which is a function of the magnitude of the displacement of the movable member from the null position; signal generator means for producing an AC reference signal having a frequency which is identical to the frequency of the AC input signal and having a phase which is the same as one phase of the AC input signal and opposite to the other phase of the AC input signal; chopper means connected to the position sensor means and to the signal generator means for rectifying the AC input signal in response to the AC reference signal to obtain a half-wave rectified DC signal having one polarity when the AC input signal and the AC reference signal are of the same phase and having the opposite polarity when the AC input signal and the AC reference signal are of opposite phase; attenuator means connected to the position sensor means for decreasing the amplitude of the AC input signal to obtain a reduced amplitude AC signal; differencer means connected to the chopper means and to the attenuator means for inverting the reduced amplitude AC signal and adding it with the half-wave rectified DC signal to obtain a full-wave rectified DC signal having the same polarity as the half-wave rectified DC signal; and filter means connected to the differencer means for averaging the amplitude of the full-wave rectified DC signal to obtain a DC output signal having a polarity which indicates the direction of the displacement of the movable member from the null position and having an amplitude which indicates the magnitude of the displacement of the movable member from the null position.

Claim 9

An apparatus for determining the direction and the magnitude of the bidirectional displacement of a movable member from a null position, the apparatus comprising: position sensing means mechanically connected with the movable member for producing a sine wave input signal having one phase when the movable member is displaced in one direction from the null position and having the opposite phase when the movable member is displaced in the opposite direction from the null position, the sine wave input signal further having an amplitude which is proportional to the magnitude of the displacement of the movable member from the null position; signal-generating means for producing a square wave reference signal having different first and second levels alternating at a frequency which is the same as the frequency of the input signal and having a phase which is the same as one phase of the input signal and opposite to the other phase of the input signal; chopping means connected to the position-sensing means and to the signal-generating means for effectively passing the input signal when the reference signal is at the first level and for effectively blocking the inpuT signal when the reference signal is at the second level, the chopping means thereby providing a half-wave rectified signal having one polarity when the input signal and the reference signal are of the same phase and having an opposite polarity when the input signal and the reference signal are of the opposite phase; attenuating means connected to the position sensing means for decreasing the amplitude of the input signal by one-half to obtain a reduced amplitude signal; differencing means connected to the chopping means and the attenuating means for subtracting the reduced amplitude signal from the half-wave rectified signal to obtain a full-wave rectified signal having the same polarity as the half-wave rectified signal; and filtering means connected to the differencing means for averaging the amplitude of the full-wave rectified signal to obtain an output signal level having a polarity which indicates the direction of the displacement of the movable member from the null position and having an amplitude which indicates the magnitude of the displacement of the movable member from the null position.

Claim 10

An apparatus for determining the direction and the magnitude of the bidirectional displacement of a movable member from a null position, the apparatus comprising: position sensing means mechanically connected with the movable member for producing a sine wave input signal having one phase when the movable member is displaced in one direction from the null position and having the opposite phase when the movable member is displaced in the opposite direction from the null position, the sine wave input signal further having an amplitude which is proportional to the magnitude of the displacement of the movable member from the null position; signal-generating means for producing a square wave reference signal having different first and second levels alternating at a frequency which is the same as the frequency of the input signal and having a phase which is the same as one phase of the input signal and opposite to the other phase of the input signal; chopping means connected to the position-sensing means and to the signal-generating means for effectively passing the input signal when the reference signal is at the first level and for effectively blocking the inpuT signal when the reference signal is at the second level, the chopping means thereby providing a half-wave rectified signal having one polarity when the input signal and the reference signal are of the same phase and having an opposite polarity when the input signal and the reference signal are of the opposite phase; attenuating means connected to the position sensing means for decreasing the amplitude of the input signal by one-half to obtain a reduced amplitude signal; differencing means connected to the chopping means and the attenuating means for subtracting the reduced amplitude signal from the half-wave rectified signal to obtain a full-wave rectified signal having the same polarity as the half-wave rectified signal; and filtering means connected to the differencing means for averaging the amplitude of the full-wave rectified signal to obtain an output signal level having a polarity which indicates the direction of the displacement of the movable member from the null position and having an amplitude which indicates the magnitude of the displacement of the movable member from the null position.