Abstract Digital data, differentially phase shift keyed on a suppressed carrier, double side band transmission, is recovered by multiplying the input signal by a signal derived from regenerative feedback and consisting of the sum of a phase-coherent carrier and the recovered data signal. The phase-coherent carrier is derived by alternate phase reversals of the incoming carrier, produced by the polarity changes in the data. The phase-coherent carrier and the recovered data signal are components of the multiplier output and are separated by bandpass and low pass filters respectively, the output terminal of the low pass filter also being the data output terminal. When a carrier has been phase modulated with two distinct signals in quadrature, the received carrier is phase shifted to produce two signals in quadrature, then each of the resultant modulated carriers is demodulated as with the single signal carrier, using one common bandpass filter.
A system for receiving and demodulating a suppressed carrier signal, phase modulated with data signal, comprising: means for multiplying the received suppressed carrier signal by a regenerative feedback signal; first filter means for recovering a phase-coherent carrier from the output of the multiplier means; second filter means for recovering the data signal from the output of the multiplier means; added means for combining the recovered phase-coherent carrier and the recovered data signal to produce the regenerative feedback signal; and an output terminal for the data signal connected to the output of the second filter means.
Claim 2
Independent Claim
95 words
A system for receiving and demodulating a suppressed carrier signal, phase modulated with data signal, comprising: means for multiplying the received suppressed carrier signal by a regenerative feedback signal; first filter means for recovering a phase-coherent carrier from the output of the multiplier means; second filter means for recovering the data signal from the output of the multiplier means; added means for combining the recovered phase-coherent carrier and the recovered data signal to produce the regenerative feedback signal; and an output terminal for the data signal connected to the output of the second filter means.
Claim 3
Independent Claim
85 words
A method of demodulating a suppressed carrier signal, phase modulated with data signal comprising the steps of: multiplying the suppressed carrier signal by a feedback signal; separating the products of the multiplication by filtering through a bandpass filter and a low pass filter respectively to produce a phase-coherent carrier and a data signal; using the output terminal for the low pass filter as an output terminal for the data signal; and adding the phase-coherent carrier to the recovered data signal to produce the feedback signal.
Claim 4
Independent Claim
85 words
A method of demodulating a suppressed carrier signal, phase modulated with data signal comprising the steps of: multiplying the suppressed carrier signal by a feedback signal; separating the products of the multiplication by filtering through a bandpass filter and a low pass filter respectively to produce a phase-coherent carrier and a data signal; using the output terminal for the low pass filter as an output terminal for the data signal; and adding the phase-coherent carrier to the recovered data signal to produce the feedback signal.