Analog-to-digital converter apparatus

Claim 2

Converting apparatus comprising, in combination: first and second signal supplying means for supplying analog signals indicative respectively of sine and cosine to be converted to a digital indication where Alpha is an angle the trigonometric functions of which are to be converted; first multiplying means including first and second inputs and an output; means connecting said first signal supplying means to said first input of said first multiplying means; second multiplying means including first and second inputs and an output; means connecting said second signal supplying means to said first input of said second multiplying means; comparator means, including input and output means, connected to receive signals from said outputs of said first and second multiplying means, said comparator means providing an analog output indicative of which of said first and second multiplying means is supplying the largest magnitude output; CORDIC type resolver means, including input means and first and second output means, said resolver means supplying outputs of sin theta and cos theta at said first and second output means respectively, wherein the values of the signals at said outputs thereof change as a function of signals supplied to the input thereof and theta is an approximation of the angle Alpha , said resolver operating over a predetermined plurality of digital word times comprising a frame of words, the cofunction sin and cos digital output signals changing on each succeeding word of a frame as a function of the polarity of the signal received from the comparator means, as a function of the word time in a frame and as a function of the value of the cofunction digital output signal in the preceding word time; means connecting said output means of said comparator means to said input means of said resolver means; means connecting said first output means of said resolver means to said second input of said first multiplying means; and means connecting second output means of said resolver means to said second input of said second multiplying meaNs.

Claim 3

Converting apparatus as claimed in claim 1 wherein said resolver comprises: first, second and third multiplying means each including signal input means, signal output means and first and second control input means; means for supplying a series of digital words to said signal input means of said first multiplying means wherein the magnitude of the words consecutively decrease during the period of a frame of words; first, second and third summing means each including first and second input means and each including output means; means connecting the output of said first multiplying means to said first input of said first summing means; first, second and third word storage means each including input means and output means, said word storage means storing the bits of a word to be outputted with the least significant bit of a word being outputted first; means connecting said first word storage means between said output of said first summing means and said second input of said first summing means; apparatus output means connected to said output of said first word storage means for providing a digital output signal indicative of the angle of a signal being generated; first and second switching means each including a plurality of inputs and a single output; means connecting the output of said second switch means to said signal input of said second multiplying means; means connecting the output of said second multiplying means to said first input of said second summing means; means connecting said second word storage means between said output of said second summing means and said second input of said second summing means; means connecting inputs of said first switch means to said second word storage means such that each input thereof receives a digital word of decreased absolute value from said word storage means as compared to that received by a previous input of said first switch means; second apparatus output means connected to said output of said second word storage means for providing a digital output signal indicative of the sine of the angle being generated; means connecting the output of said first switch means to said signal input of said third multiplying means; means connecting the output of said third multiplying means to said first input of said third summing means; means connecting said third word storage means between said output of said third summing means and said second input of said third summing means; means for inserting a predetermined word value into the said third word storage means during the first word of a frame of words; means for connecting a plurality of inputs of said second switch means to said third word storage means such that successive inputs thereof receive digital words of decreased absolute value from said word storage means as compared to that received by a previous input to said second switch means; third apparatus output means connected to said output of said third word storage means for providing an output indicative of the cosine of the angle generated; and means for supplying control signals to said first and second control inputs of said first, second and third multiplying means.

Claim 4

Digital apparatus operating over a plurality of words constituting a frame of words comprising, in combination: first, second and third multiplying means each including signal input means, signal output means and first and second control input means; means for supplying a series of digital words to said signal input means of said first multiplying means wherein the magnitude of the words consecutively decrease during the period of a frame of words; first, second and third summing means each including first and second input means and each including output means; means connecting the output of said first multiplying means to said first input of said first summing means; first, second and third word storage means eAch including input means and output means, said word storage means storing the bits of a word to be outputted with the least significant bit of a word being outputted first; means connecting said first word storage means between said output of said first summing means and said second input of said first summing means; apparatus output means connected to said output of said first word storage means for providing a digital output signal indicative of the angle of a signal being generated; first and second switching means each including a plurality of inputs and a single output; means connecting the output of said second switch means to said signal input of said second multiplying means; means connecting the output of said second multiplying means to said first input of said second summing means; means connecting said second word storage means between said output of said second summing means and said second input of said second summing means; means connecting inputs of said first switch means to said second word storage means such that each input thereof receives a digital word of decreased absolute value from said word storage means as compared to that received by a previous input of said first switch means; second apparatus output means connected to said output of said second word storage means for providing a digital output signal indicative of the sine of the angle being generated; means connecting the output of said first switch means to said signal input of said third multiplying means; means connecting the output of said third multiplying means to said first input of said third summing means; means connecting said third word storage means between said output of said third summing means and said second input of said third summing means; means for inserting a predetermined word value into the said third word storage means during the first word of a frame of words; means for connecting a plurality of inputs of said second switch means to said third word storage means such that successive inputs thereof receive digital words of decreased absolute value from said word storage means as compared to that received by a previous input to said second switch means; third apparatus output means connected to said output of said third word storage means for providing an output indicative of the cosine of the angle being generated; and means for supplying control signals to said first and second control inputs of said first, second and third multiplying means.

Claim 5

Digital apparatus operating over a plurality of words constituting a frame of words comprising, in combination: first, second and third multiplying means each including signal input means, signal output means and first and second control input means; means for supplying a series of digital words to said signal input means of said first multiplying means wherein the magnitude of the words consecutively decrease during the period of a frame of words; first, second and third summing means each including first and second input means and each including output means; means connecting the output of said first multiplying means to said first input of said first summing means; first, second and third word storage means eAch including input means and output means, said word storage means storing the bits of a word to be outputted with the least significant bit of a word being outputted first; means connecting said first word storage means between said output of said first summing means and said second input of said first summing means; apparatus output means connected to said output of said first word storage means for providing a digital output signal indicative of the angle of a signal being generated; first and second switching means each including a plurality of inputs and a single output; means connecting the output of said second switch means to said signal input of said second multiplying means; means connecting the output of said second multiplying means to said first input of said second summing means; means connecting said second word storage means between said output of said second summing means and said second input of said second summing means; means connecting inputs of said first switch means to said second word storage means such that each input thereof receives a digital word of decreased absolute value from said word storage means as compared to that received by a previous input of said first switch means; second apparatus output means connected to said output of said second word storage means for providing a digital output signal indicative of the sine of the angle being generated; means connecting the output of said first switch means to said signal input of said third multiplying means; means connecting the output of said third multiplying means to said first input of said third summing means; means connecting said third word storage means between said output of said third summing means and said second input of said third summing means; means for inserting a predetermined word value into the said third word storage means during the first word of a frame of words; means for connecting a plurality of inputs of said second switch means to said third word storage means such that successive inputs thereof receive digital words of decreased absolute value from said word storage means as compared to that received by a previous input to said second switch means; third apparatus output means connected to said output of said third word storage means for providing an output indicative of the cosine of the angle being generated; and means for supplying control signals to said first and second control inputs of said first, second and third multiplying means.

Claim 6

Apparatus as claimed in claim 3 wherein: said means for supplying control signals comprise first and second leads wherein the first lead is connected to said first control means of said first and second multiplying means and to said second control means of said third multiplying means; and said second lead is connected to said input of said first and second multiplying means and connected to said first input of said third multiplying means.