Sum or difference angle computation apparatus

Claim 2

Apparatus responsive to signals representative of functions of first and second angle variables for producing a signal proportional to a function of the algebraic difference between the angle variables, comprising means for combining a signal S1 representative of a function of the first angle variable with a signal S2 representative of a function of the second angle variable to produce a resultant combined signal, means for combining a signal S3 representative of another function of the first angle variable with a signal S4 representative of another function of the second angle variable to produce another resultant combined signal, the first angle variable being an amplitude modulation factor of a carrier component associated with signals S1 and S3 and the second angle variable being an amplitude modulation factor of another carrier component of different frequency associated with signals S2 and S4, and means for multiplying the two combined signals to produce a composite signal containing a signal component proportional to a function of the algebraic difference between the angle variables.

Claim 3

The apparatus of claim 1 wherein said resultant signal is equal to S1 - S2 and said another resultant signal is equal to S3 + S4.

Claim 4

The apparatus of claim 1 including a frequency selective device connected to receive the composite signal for separating the signal proportional to a function of the algebraic difference between the angle variables from the remainder of the composite signal.

Claim 5

The apparatus of claim 1 wherein the carrier component of the signals corresponding to one of the first and second angle variables is a d.c. component which is amplitude modulated in accordance with the instantaneous value of the related angle variable.

Claim 6

The apparatus of claim 1 in which the functions of the first and second angle variables are cyclically varying trigonometric functions.

Claim 7

The apparatus of claim 5 in which the functions of the first and second angle variables are respective sine and cosine functions.

Claim 8

The apparatus of claim 6 wherein the carrier component of the functions of one of the first and second angle variables is a d.c. component whereby the composite signal produced at the output of said multiplier includes a d.c. component, a second harmonic component of the carrier frequency of the function of the other of the first and second angle variables, and a component proportional to a trigonometric function of the algebraic difference between the angle variables.

Claim 9

The apparatus of claim 7 including a frequency selective device connected to receive the composite signal from said multiplier and provide at its output the signal proportional to a trigonometric function of the algebraic difference between the angle variables.

Claim 10

An all electronic resolver comprising means for receiving a plurality of variable input signals, two of said input signals being a function of a first variable angle which is an amplitude modulation factor of a carrier component of predetermined frequency associated with said two input signals and an additional two of said input signals being a function of a second variable angle which is an amplitude modulation factor of a carrier component of a different pre-determined frequency associated with said additional two input signals, first means for linearly combining a first pair of said input signals, second means for linearly combining a second pair of said input signals, third means for multiplying the resultant signal from said first means with the resultant signal of said second means, first frequency selective means for passing solely a signal component constituting an output of the electronic resolver proportional to a function of the algebraic difference of the variable signals of said first and second pair of input signals, fourth means for linearly combining a third pair of said input signals wherein one signal of said third pair is one of the signals in said first pair and the other signal of said third pair is one of the signals in said second pair, fifth means for linearly combining a fourth pair of said input signals wherein one signal of said fourth pair is the remaining one of the signals in said first pair and the other signal of said fourth pair is the remaining one of the signals iN said second pair, sixth means for multiplying the resultant signal from said fourth means with the resultant signal of said fifth means, second frequency selective means for passing solely a signal component constituting another output of the electronic resolver proportional to a function of the algebraic difference of the variable signals of said third and fourth pair of input signals, and one signal of each of said pairs of signals being selected from said two input signals having one carrier component and the other signal of each of said pairs of signals being selected from said additional two input signals having a different carrier frequency component.

Claim 11

An all electronic resolver comprising means for receiving a plurality of variable input signals, two of said input signals being a function of a first variable angle which is an amplitude modulation factor of a carrier component of predetermined frequency associated with said two input signals and an additional two of said input signals being a function of a second variable angle which is an amplitude modulation factor of a carrier component of a different pre-determined frequency associated with said additional two input signals, first means for linearly combining a first pair of said input signals, second means for linearly combining a second pair of said input signals, third means for multiplying the resultant signal from said first means with the resultant signal of said second means, first frequency selective means for passing solely a signal component constituting an output of the electronic resolver proportional to a function of the algebraic difference of the variable signals of said first and second pair of input signals, fourth means for linearly combining a third pair of said input signals wherein one signal of said third pair is one of the signals in said first pair and the other signal of said third pair is one of the signals in said second pair, fifth means for linearly combining a fourth pair of said input signals wherein one signal of said fourth pair is the remaining one of the signals in said first pair and the other signal of said fourth pair is the remaining one of the signals iN said second pair, sixth means for multiplying the resultant signal from said fourth means with the resultant signal of said fifth means, second frequency selective means for passing solely a signal component constituting another output of the electronic resolver proportional to a function of the algebraic difference of the variable signals of said third and fourth pair of input signals, and one signal of each of said pairs of signals being selected from said two input signals having one carrier component and the other signal of each of said pairs of signals being selected from said additional two input signals having a different carrier frequency component.