Carrier frequency phase-readjustment device

Claim 2

In a communications system of the type transmitting a representation of a carrier signal and one sideband of the product of said carrier signal and an information signal including a synchronizing signal having at least a pair of integral harmonically related signals having a fixed phase relationship, a receiver including in combination, means responsive to the reception of said transmitted signal to generate a carrier signal having a frequency and phase corresponding to the received carrier signal, filter means responsive to said received information signal to regenerate a signal at the received carrier frequency and of the phase required for demodulation of the information signal, a pulse generator driven by said filter means to provide a pulse each time the regenerated carrier signal has a predetermined phase angle, a gate responsive to said pulses from said pulse generator and to a synchronizing signal to pass said pulses during a synchronizing period, a second carrier signal generator connected to said gate and responsive to said pulses from said gate to generate another carrier signal having a phase corresponding to that of said regenerated signal and, a demodulator connected to receive said transmitted signal and said second carrier signal and operating to provide a received information signal.

Claim 3

A communications system receiver as in claim 1 in which said filter means comprises; a beat frequency device responsive to said received signal to generate a signal corresponding to the difference of said pair of signals, a filter on the output of said beat frequency device to block transfer of all but said difference frequency of said pair of signals, a wave shaper and frequency divider driven by said filter to generate a square wave at a subharmonic of said difference frequency and, a modulator connected to receiving said square wave and said received signal and operative to provide a regenerated carrier signal.

Claim 4

A communication system receiver as in claim 1 which said filter means comprises: a filter to extract said pair of signals from said received signal, a nonlinear circuit on the output of said filter to provide a cubic multiplication of said pair of signals, and another filter receiving the output of said nonlinear circuit and passing only the frequency corresponding to said regenerated carrier signal.

Claim 5

In a communications system of the type transmitting a carrier signal and the lower sideband resulting from modulation of said carrier signal by an inFormation signal, said information signal during an initial synchronizing period including at least a pair of signals having an integral harmonic relationship, a receiver including in combination; a demodulator receiving said transmitted information signal and a phase adjusted carrier signal to regenerate said information signal, a device responsive to said transmitted carrier signal to generate a carrier signal having a frequency and phase corresponding to said carrier signal as received, means responsive to the received modulated representations of said pair of signals to generate signals indicating the carrier signal phase needed for demodulation of said received information signal, means connected to said responsive means to pass said phase indicating signals during an initial synchronizing period and, a second carrier signal generator connected to said carrier signal generating device to introduce a phase shift between said generated carrier signal and said second carrier signal, said second carrier signal generator connected to receive said passed phase indicating signals and responsive thereto to provide phase adjusted carrier signals over a connection to said demodulator.

Claim 6

In a communications system of the type transmitting a carrier signal and the lower sideband resulting from modulation of said carrier signal by an inFormation signal, said information signal during an initial synchronizing period including at least a pair of signals having an integral harmonic relationship, a receiver including in combination; a demodulator receiving said transmitted information signal and a phase adjusted carrier signal to regenerate said information signal, a device responsive to said transmitted carrier signal to generate a carrier signal having a frequency and phase corresponding to said carrier signal as received, means responsive to the received modulated representations of said pair of signals to generate signals indicating the carrier signal phase needed for demodulation of said received information signal, means connected to said responsive means to pass said phase indicating signals during an initial synchronizing period and, a second carrier signal generator connected to said carrier signal generating device to introduce a phase shift between said generated carrier signal and said second carrier signal, said second carrier signal generator connected to receive said passed phase indicating signals and responsive thereto to provide phase adjusted carrier signals over a connection to said demodulator.

Claim 7

A communications system receiver as in claim 4 in which said responsive means comprises; a beat frequency device responsive to said received signal to generate a signal corresponding to the difference of said pair of signals, a filter on the output of said beat frequency device to block transfer of all but said difference frequency of said pair of signals, a wave shaper and a frequency divider connected to said filter to generate a square wave at a subharmonic of said difference frequency and, a modulator connected to receive said square wave and said received signal to provide a regenerated carrier signal.

Claim 8

A communications system receiver as in claim 4 in which said responsive means comprises; a filter to extract said pair of signals from said received signal, a nonlinear circuit on the output of said filter to provide a cubic multiplication of said pair of signals, and another filter receiving the output of said nonlinear circuit and passing only the frequency corresponding to said regenerated carrier signal.