Differentially coherent phase shift keyed digital demodulating apparatus

Claim 5

The method of claim 2 wherein the generation of the updating signal comprises the following steps repeatedly and sequentially N times: multiplying a given test angle by the first and second components; subtracting one product from the other; modifying the phase of said test angle in accordance with the polarity of the difference result of the subtraction.

Claim 6

Apparatus for detecting the phase shift of a received signal with respect to the phase of a periodically phase updated reference signal comprising, in combination: reference means for providing a periodically digital number updated reference angle signal; phase to amplitude signal conversion means connected to said reference means to provide said periodically phase updated signal; input means for supplying a received signal to be phase detected; detection means, connected to said input means and said conversion means, for supplying two phase separated component signals indicative of the phase of the input signal with respect to the reference angle; first and second storage means for temporarily storing the two phase-separated signals; test angle generating means, connected to said storage means, for providing a first digital number signal indicative of the phase angle of the received signal; and updating means connected to said generating means and said reference means for updating the digital number reference angle signal by the amount of said first signal from said generating means.

Claim 7

Apparatus for detecting the phase shift of a received signal with respect to the phase of a periodically phase updated reference signal comprising, in combination: reference means for providing a periodically digital number updated reference angle signal; phase to amplitude signal conversion means connected to said reference means to provide said periodically phase updated signal; input means for supplying a received signal to be phase detected; detection means, connected to said input means and said conversion means, for supplying two phase separated component signals indicative of the phase of the input signal with respect to the reference angle; first and second storage means for temporarily storing the two phase-separated signals; test angle generating means, connected to said storage means, for providing a first digital number signal indicative of the phase angle of the received signal; and updating means connected to said generating means and said reference means for updating the digital number reference angle signal by the amount of said first signal from said generating means.

Claim 8

Apparatus as claimed in claim 4 comprising, in addition output means for providing a second signal indicative of the phase shift of the received signal with respect to the previously received signal.

Claim 9

Apparatus as claimed in claim 4 wherein the two-phase separated signals of said detection means are separated by 90 degrees and include polarity bits and comprising, in addition, output means for determining the phase shift of said input signal in accordance with two polarity bits of said phase separated signals.

Claim 10

Apparatus as claimed in claim 4 for detecting a plurality of N tones comprising in addition: N detection means; means for storing N periodically updated reference signals to be retrieved sequentially for use with each detection means in sequence; and means for sequentially connecting said test angle generating means and said updating means to said N detection means and said reference means respectively to determine the angle of each of the N tone received signals and then to update the respective reference angle signal corresponding to that tone.

Claim 11

Apparatus as claimed in claim 4 wherein said test angle generating means comprises: means for supplying a test angle Alpha ; means for multiplying and subtracting the two phase-separated signals by said variable test angle Alpha in accordance with P Y cos Alpha - X sin Alpha where P is the polarity of the answer and X and Y are the phase-separated signals and are separated by 90* and supplying the signal P for N times; and means for modifying the test angle Alpha in accordance with the polarity of P each of N times.

Claim 12

Apparatus for detecting the phase shift of a received data signal with respect to a past data period comprising, in combination: means for detecting the phase of a received signal with respect to a reference signal and supplying an output indicative thereof; means, connected to said last named means, for generating a phase representative digital number updating signal by comparing and adjusting the phase of a test angle signal with the detected phase components obtained by the last named means; means for digitally adding said updating signal to a digital number representation of said digital number representation of reference signal for updating said reference signal means for converting said digital number representation of said reference signal from a phase to amplitude signal to produce said reference signal in updated form for detecting further input phase shift data.

Claim 13

Apparatus for detecting the phase shift of a received data signal with respect to a past data period comprising, in combination: means for detecting the phase of a received signal with respect to a reference signal and supplying an output indicative thereof; means, connected to said last named means, for generating a phase representative digital number updating signal by comparing and adjusting the phase of a test angle signal with the detected phase components obtained by the last named means; means for digitally adding said updating signal to a digital number representation of said digital number representation of reference signal for updating said reference signal means for converting said digital number representation of said reference signal from a phase to amplitude signal to produce said reference signal in updated form for detecting further input phase shift data.

Claim 14

The apparatus recited in claim 9 wherein the means for generating the updating signal comprises: mean for multiplying the test angle signal by first and second components of the received signal; means for subtracting one product from the other; and means for modifying the phase of said test angle signal in accordance with the polarity of the difference result of the subtraction.

Claim 15

Apparatus as recited in claim 10 wherein the test angle originally supplied by said means for multiplying is pi radians and where the means for modifying the test angle changes the angle by one-half the previous change starting with pi /2.

Claim 18

Demodulating apparatus comprising, in combination: first means for supplying an input signal to be demodulated; second means for supplying a reference signal at an output thereof wherein said second means includes input means to accept phase updating correction signals; first and second detection means, connected to said first and second means, for supplying two 90* phase separated digital signals indicative of the quadrature components of the input signal with respect to said reference signal; first and second storage means for storing the output signals from said first and second detection means respectively wherein the stored signal is a digital signal directly indicative of the phase angle of said input signal with respect to said reference and to a full 360* electrical cycle; third means for supplying periodic and sequentially smaller test angle signals for phase measurement purposes; fourth means for storing the accumulated test angle; fifth means, connected to said third and fourth means for passing signals from said third to said fourth means, and for incrementing the test angle signal phase magnitude stored in said fourth means in accordance with the polarity of an input supplied thereto; comparison means, connected to said fourth means and said first and second storage means, for comparing the output signals stored in said first and second storage means with the signal stored in said fourth means and supplying an output signal to said fifth means indicative in polarity of the comparison result; and sixth means for supplying a signal to said input means of said second means indicative of the final accumulated test angle stored in said fourth means for phase updating the reference signal in said second means.

Claim 19

Demodulating apparatus comprising, in combination: first means for supplying an input signal to be demodulated; second means for supplying a reference signal at an output thereof wherein said second means includes input means to accept phase updating correction signals; first and second detection means, connected to said first and second means, for supplying two 90* phase separated digital signals indicative of the quadrature components of the input signal with respect to said reference signal; first and second storage means for storing the output signals from said first and second detection means respectively wherein the stored signal is a digital signal directly indicative of the phase angle of said input signal with respect to said reference and to a full 360* electrical cycle; third means for supplying periodic and sequentially smaller test angle signals for phase measurement purposes; fourth means for storing the accumulated test angle; fifth means, connected to said third and fourth means for passing signals from said third to said fourth means, and for incrementing the test angle signal phase magnitude stored in said fourth means in accordance with the polarity of an input supplied thereto; comparison means, connected to said fourth means and said first and second storage means, for comparing the output signals stored in said first and second storage means with the signal stored in said fourth means and supplying an output signal to said fifth means indicative in polarity of the comparison result; and sixth means for supplying a signal to said input means of said second means indicative of the final accumulated test angle stored in said fourth means for phase updating the reference signal in said second means.