Receiver for amplitude modulated quadrature carrier signals

Claim 2

A receiver for a quadrature carrier, amplitude modulated signal which carries digital data in sets of digital bits, each set including at least two bits, comprising: A. demodulating means for recovering demodulated data signals, said demodulating means including variable control means for at least one operating parameter of said demodulating means, said variable control means including strobing means responsive to the appearance of each set of data bits for generating a strobing signal, B. decoding means connected to said demodulating means and responsive to the strobing signal for converting the demodulated data signals into signals corresponding to the digital data, C. error means connected to said decoding means and said demodulating means for generating an error signal representing the difference between the actual and expected values of the demodulated data signals for each successive set of decoded digital data bits, and D. parameter control means responsive to the error signals for varying said variable control means to minimize the difference between the actual and expected values.

Claim 3

A receiver as recited in claim 1 wherein the timing of the strobing signal is an operating parameter, said parameter control means monitoring the error signal to control the timing of the strobing signal from said strobing means.

Claim 4

divider means responsive to said clock pulses for normally generating the strobe signal at the center of a baud time, said divider including first correction means responsive to an advance signal to cause said strobe signal to occur earlier in a baud time and second correction means responsive to a retard signal to cause the strobe signal to occur later in a baud time, B. means in said demodulator means for generating differential signals representing the rate of change of the demodulated data signals, said means being responsive to the selection signals for generating a differential error signal, C. means responsive to the summed demodulated data signals at the time the strobe signal appears for generating a constant width, variable height pulse, and D. conversion means for converting the pulse signal to a constant height, variable width timing error pulse for generating the advance or retard signal depending upon the polarity of the timing error pulse.

Claim 5

divider means responsive to said clock pulses for normally generating the strobe signal at the center of a baud time, said divider including first correction means responsive to an advance signal to cause said strobe signal to occur earlier in a baud time and second correction means responsive to a retard signal to cause the strobe signal to occur later in a baud time, B. means in said demodulator means for generating differential signals representing the rate of change of the demodulated data signals, said means being responsive to the selection signals for generating a differential error signal, C. means responsive to the summed demodulated data signals at the time the strobe signal appears for generating a constant width, variable height pulse, and D. conversion means for converting the pulse signal to a constant height, variable width timing error pulse for generating the advance or retard signal depending upon the polarity of the timing error pulse.

Claim 6

gating means responsive to a strobe signal for coupling selected summed demodulated data signals to said low pass filter to thereby alter the phase control signal, and C. said error means including a strobe generator responsive to a minimum difference between actual and expected values for the modulated data signals for generating the strobe signal.

Claim 7

gating means responsive to a strobe signal for coupling selected summed demodulated data signals to said low pass filter to thereby alter the phase control signal, and C. said error means including a strobe generator responsive to a minimum difference between actual and expected values for the modulated data signals for generating the strobe signal.

Claim 8

A receiver as recited in claim 2 wherein the amplitude of the modulated carrier signal varies as a function of data and said decoding means generates additional digital data based upon the amplitude of the carrier signal and the amplitude is an operating parameter control, said demodulating means including adjustable gain amplifier means for the incoming carrier signal, and said parameter control means monitoring said error signal to control the gain of said adjustable gain amplifier means.

Claim 9

A receiver as recited in claim 1 wherein said demodulating means includes an oscillator, and the phase of said oscillator output signal is an operating parameter, said parameter control means monitoring the error signal to control the phase of said oscillator.

Claim 10

A receiver recited in claim 4 wherein the timing of the strobing signals is a second operation parameter, said demodulator including second parameter control means monitoring the error signal to control the timing of the strobing signal from said strobing means.

Claim 11

A receiver as recited in claim 5 wherein the amplitude of the demodulated carrier signal varies as a function of data and said decoding means generates additional digital data based upon the amplitude of the carrier signals, and the amplitude is a third operating parameter, said demodulating means including adjustable gain carrier amplifier means for the incoming carrier signal and third parameter control means monitoring the error signal to control the gain of said adjustable gain amplifier means.

Claim 12

A receiver as recited in claim 4 wherein the amplitude of the modulated carrier signal varies as a function of data and said decoding means generates additional digital data based upon the amplitude of the carrier signal and the amplitude is another operating parameter, said demodulating means including adjustable gain carrier amplifier means for the incoming carrier signal and additional parameter control means for monitoring the error signal to control the gain of said adjustable gain amplifier means.

Claim 13

A receiver for incoming quadrature carrier, amplitude modulated signals modulated in response to sets of digital data, each set including at least two data bits, said receiver comprising: A. demodulating means for recovering phase-displaced demodulated data signals from the incoming signals including a variable phase oscillator means and means for adjusting the phase of said oscillator means, B. decoding means connected to said demodulating means for converting each successive set of demodulated data signals into corresponding digital data, C. error means connected to said decoding means and said demodulating means for generating an error signal representing for each successive set of data bits the difference between the actual and expected values of the demodulated data signals for the decoded digital data, and D. carrier phase control means responsive to signals from said decoding means and said error means for generating a phase control signal for controlling the relative phases of said oscillator output and incoming carrier signals to minimize the difference between the actual and expected values of the demodulated data signals.

Claim 14

A receiver for incoming quadrature carrier, amplitude modulated signals modulated in response to sets of digital data, each set including at least two data bits, said receiver comprising: A. demodulating means for recovering phase-displaced demodulated data signals from the incoming signals including a variable phase oscillator means and means for adjusting the phase of said oscillator means, B. decoding means connected to said demodulating means for converting each successive set of demodulated data signals into corresponding digital data, C. error means connected to said decoding means and said demodulating means for generating an error signal representing for each successive set of data bits the difference between the actual and expected values of the demodulated data signals for the decoded digital data, and D. carrier phase control means responsive to signals from said decoding means and said error means for generating a phase control signal for controlling the relative phases of said oscillator output and incoming carrier signals to minimize the difference between the actual and expected values of the demodulated data signals.

Claim 15

A receiver as recited in claim 8 additionally comprising: A. means in said demodulating means for generating differential signals representing the rate of change of the demodulated data signals, B. sampling means in said demodulating means responsive to a strobe signal for periodically sampling the demodulated data signals, C. a strobe signal generator in said demodulating means decoding data signals including variable clock means for periodically generating the strobe signal, D. means in said error means responsive to the strobe signal for sampling the differential signals and error signal to generate a strobe control signal, and E. means responsive to the stRobe control signal to alter the timing of said variable clock means to minimize the difference between the actual and expected values of the demodulated data signals which exists during the strobe signal.

Claim 16

A receiver as recited in claim 8 wherein said error means includes: A. means in said decoding means responsive to the demodulated data signals for generating absolute phase signals, B. means for summing selected ones of the demodulated data signals for generating the error signal, and C. means responsive to the absolute phase signals for generating selection signals for controlling said summing means so the error signal causes said carrier phase control means to alter the phase of said oscillator output signal.

Claim 17

A receiver as recited in claim 10 additionally comprising: A. means in said demodulating means for generating differential signals representing the rate of change of the demodulated data signals, B. means in said demodulating means for periodically sampling the output from said demodulating means in response to a strobe signal, C. a generator for periodically producing a strobe signal, said generator including a clock pulse generator, divider means for periodically generating the strobe signal including first correction means responsive to a retard signal to block pulses periodically from said clock pulse generator and second correction means responsive to an advance signal for adding pulses periodically to those received from said clock pulse generator to thereby vary the timing of the strobe signal, and means for summing selected ones of said differential signals in response to the selection signals, and D. means responsive to the summed differential signals and the error signal for generating a timing error signal representing the difference between the time of a strobe signal and the time at which the minimum difference between the actual and expected values of the demodulated data signals occurs, the timing error signal being coupled to said first or second correction means.

Claim 18

A receiver as recited in claim 11 wherein said timing error signal means includes means for generating a constant width, variable height pulse of a first polarity to indicate an early strobe timing signal or of a second polarity to indicate a late strobe timing signal and means for converting the pulse height to a constant height, variable width pulse for the first or second correction means.

Claim 19

A receiver as recited in claim 10 wherein the demodulated data signals from said demodulating means are in the form of demodulated differential phase shift keyed signal and include first and second sets of signals corresponding to first and second coordinate systems, respectively, said receiver additionally comprising: A. coordinate means for indicating whether the component signals are in the first or second set, and B. means in said absolute phase generating means for comparing the demodulated data signals in the first set against fixed reference values and demodulated data signals in the second set against each other to obtain the absolute phase signals.

Claim 20

A receiver as recited in claim 13 wherein: A. said variable phase oscillator means comprises voltage controlled oscillator means responsive to the phase control signal, B. said carrier phase control means includes:

Claim 21

A receiver as recited in claim 14 wherein the time between successive phase shifts of the modulated data signal constitutes a baud time: A. said stRobe generator including:

Claim 22

A receiver as recited in claim 8 additionally comprising: A. adjustable gain amplifier means for the incoming carrier signals, and B. gain control means responsive to signals from said decoding means and said error means for generating a gain control signal for said adjustable gain amplifier means to minimize the difference between the actual and expected values of the modulated data signals.

Claim 23

A receiver as recited in claim 16 wherein said gain control means includes: A. means for comparing selected demodulated data signals with a reference level to generate a different signal, and B. means to specifically sample the difference signal, C. filtering means to convert the output from said difference signal sampling means to generate the gain control signal.

Claim 24

A receiver for incoming quadrature carrier, amplitude modulated signals modulated in response to sets of digital bits, each set including at least two bits, said receiver comprising: A. means including a sampling means for recovering the digital data, B. means for generating phase displaced demodulated signals and differential signals representing the rate of change of the demodulated data signals, C. variable timing means for generating a strobe signal for controlling the timing of said sampling means, D. means generating an error signal corresponding to the difference between actual and expected values of each successive set of the demodulated data bits, and E. means responsive to the strobe signal and the error signal for generating a timing control signal, said variable timing means being responsive to the timing control signal to shift the timing of the strobe signal to the minimize the difference between the actual and expected values of the demodulated data signals.

Claim 25

A receiver for incoming quadrature carrier, amplitude modulated signals modulated in response to sets of digital bits, each set including at least two bits, said receiver comprising: A. means including a sampling means for recovering the digital data, B. means for generating phase displaced demodulated signals and differential signals representing the rate of change of the demodulated data signals, C. variable timing means for generating a strobe signal for controlling the timing of said sampling means, D. means generating an error signal corresponding to the difference between actual and expected values of each successive set of the demodulated data bits, and E. means responsive to the strobe signal and the error signal for generating a timing control signal, said variable timing means being responsive to the timing control signal to shift the timing of the strobe signal to the minimize the difference between the actual and expected values of the demodulated data signals.