Synchronizing system for phase-modulation telecommunication system

Claim 2

A demodulator for a synchronizing system for a phasemodulation telecommunication system using a burst signal including a preamble word portion so phase-modulated as to take alternate phases Alpha and Beta (where both Alpha and Beta are arbitrary phase, with Beta - Alpha being unequal to 0 or pi ) and an immediately subsequent information word portion so N-phase phase modulated as to take phases (2 pi /N)i (where N is a positive integer and i 0, 1, 2, ..., or N-1), said demodulator comprising: a. a reference carrier wave extraction circuit having a bandpass filter with its center frequency present equal to the carrier frequency of a received signal including said brust signal and an amplitude limiter connected in cascade therewith, b. an N-phase phase detector for detecting the phase of the received signal with respect to that of the reference carrier wave, c. a controlled N-phase phase modulator, having input terminal for said detected output, input terminal for said received signal, and control terminal for receiving a control signal, for providing a first or a second output signal depending on whether said control signal is in a first or a second state, said first output signal being identical to said received signal while said second output signal corresponding to the received signal phase-modulated in response to said detected output, d. a phase shifter, having a control terminal for receiving said control signal, for adding an amount of phase shift ( Alpha + Beta )/2 + (2 pi /N)j (j 0, 1, 2, ..., or N-1) to the phase of a signal passing therethrough in response to the control signal, and e. means for generating said control signal at least without a time delay with respect to the boundary between said preamble word and information word portions of said received signal in such a way that the control signal state can be switched from said first state to said second state.

Claim 3

A demodulator for a synchronizing system in a phase-modulation telecommunication system using a burst signal including a preamble word portion so phase-modulated as to have alternate phases Alpha and Beta where both Alpha and Beta are arbitary phases with Beta - Alpha being unequal to 0 or pi , said preamble having an effective phase of Alpha + Beta /2, and an immediately subsequent information word portion so N-phase phase modulated as to take phases (2 pi /N)i where N is a positIve integer and i 0, 1, 2, ..., or N- 1, said demdulator comprising: a. a reference carrier wave extraction circuit for extracting a reference carrier wave from said burst signal and having a bandpass filter with its center frequency equal to the carrier frequency of a received signal including said burst signal, and an amplitude limiter connected in cascade with said extraction circuit; b. an N-phase phase detector for detecting the phase of the received signal relative to that of the extracted reference carrier wave and producing a detected output indicative of the relative phase; c. a controlled N-phase phase modulator, having an input terminal for receiving said detected output, an input terminal for said received signal, and a control terminal for receiving a control signal; said modulator providing a first or a second output signal depending on whether said control signal is in a first or a second state, said first output signal being identical to said received signal and said second output signal corresponding to the received signal phase-modulated in response to said detector output, said output signals being applied to said extraction circuit; d. a phase shifter, having a control terminal for receiving said control signal, and responsive to the second state thereof for adding an amount of phase shift ( Alpha + Beta )/2 + (2 pi /N)j (j 0, 1, 2, ..., or N-1) to the phase of said second output signal; and e. means responsive to the received signal for generating said control signal so that it switches from said first state to said second state at a time related to the time of occurrence of the boundary between said preamble word and information word portions of said received signal whereby said extracted reference carrier has the same phase during both said preamble and information word portions, and no discontinuity occurs in said reference carrier at said boundary.

Claim 4

A demodulator for a synchronizing system in a phase-modulation telecommunication system using a burst signal including a preamble word portion so phase-modulated as to have alternate phases Alpha and Beta where both Alpha and Beta are arbitary phases with Beta - Alpha being unequal to 0 or pi , said preamble having an effective phase of Alpha + Beta /2, and an immediately subsequent information word portion so N-phase phase modulated as to take phases (2 pi /N)i where N is a positIve integer and i 0, 1, 2, ..., or N- 1, said demdulator comprising: a. a reference carrier wave extraction circuit for extracting a reference carrier wave from said burst signal and having a bandpass filter with its center frequency equal to the carrier frequency of a received signal including said burst signal, and an amplitude limiter connected in cascade with said extraction circuit; b. an N-phase phase detector for detecting the phase of the received signal relative to that of the extracted reference carrier wave and producing a detected output indicative of the relative phase; c. a controlled N-phase phase modulator, having an input terminal for receiving said detected output, an input terminal for said received signal, and a control terminal for receiving a control signal; said modulator providing a first or a second output signal depending on whether said control signal is in a first or a second state, said first output signal being identical to said received signal and said second output signal corresponding to the received signal phase-modulated in response to said detector output, said output signals being applied to said extraction circuit; d. a phase shifter, having a control terminal for receiving said control signal, and responsive to the second state thereof for adding an amount of phase shift ( Alpha + Beta )/2 + (2 pi /N)j (j 0, 1, 2, ..., or N-1) to the phase of said second output signal; and e. means responsive to the received signal for generating said control signal so that it switches from said first state to said second state at a time related to the time of occurrence of the boundary between said preamble word and information word portions of said received signal whereby said extracted reference carrier has the same phase during both said preamble and information word portions, and no discontinuity occurs in said reference carrier at said boundary.

Claim 5

A demodulator as defined in claim 2 wherein said phase shifter is connected between said phase modulator and said extraction circuit so that said first and second output signals pass therethrough, said phase shifter being responsive to said first state of said control signal to impart a zero phase shift to said first output signal passing therethrough.

Claim 6

A demodulator as defined in claim 2 wherein said control signal switches from said first to said second state at the time of occurrence of said boundary.

Claim 7

A demodulator as defined in claim 2 wherein said control signal switches from said first to said second state prior to the occurrence of said boundary to compensate for possible malfunction of said control signal generating means.

Claim 8

In a synchronizing system for a phase-modulation telecommunication system using a burst signal including a preamble word portion so phase-modulated as to take alternate phases Alpha and Beta where both Alpha and Beta are arbitrary phases with Beta - Alpha being unequal to 0 or pi , said preamble having an effective phase of Alpha + Beta /2, and an immediately subsequent information word portion so N-phase phase modulated as to take phases (2 pi /N)i where N is a positive integer and i 0, 1, 2, ..., or N-1, a method of reducing the time required to regenerate a reference carrier signal from a received signal including said burst signal comprising: a. filtering out the carrier frequency of the preamble word portion of said received signal and extracting therefrom a reference carrier signal having a phase of Alpha + Beta /2; b. reverse N-phase phase modulating the information word portion of the received signal and imparting thereto a phase shift of ( Alpha + Beta )/2 + (2 pi /N)j(j 0, 1, 2, ..., or N-1); c. filtering out the carrier frequency from the reversely modulated and phase-shifted signal proDuced in paragraph (b) and extracting therefrom a reference carrier signal, whereby the reference carrier signal is continuously recovered across the boundary of the preamble and information word portions of the received signal; and d. phase detecting the received signal relative to the extracted reference carrier signals to demodulate the phase-modulated received signal.

Claim 9

In a synchronizing system for a phase-modulation telecommunication system using a burst signal including a preamble word portion so phase-modulated as to take alternate phases Alpha and Beta where both Alpha and Beta are arbitrary phases with Beta - Alpha being unequal to 0 or pi , said preamble having an effective phase of Alpha + Beta /2, and an immediately subsequent information word portion so N-phase phase modulated as to take phases (2 pi /N)i where N is a positive integer and i 0, 1, 2, ..., or N-1, a method of reducing the time required to regenerate a reference carrier signal from a received signal including said burst signal comprising: a. filtering out the carrier frequency of the preamble word portion of said received signal and extracting therefrom a reference carrier signal having a phase of Alpha + Beta /2; b. reverse N-phase phase modulating the information word portion of the received signal and imparting thereto a phase shift of ( Alpha + Beta )/2 + (2 pi /N)j(j 0, 1, 2, ..., or N-1); c. filtering out the carrier frequency from the reversely modulated and phase-shifted signal proDuced in paragraph (b) and extracting therefrom a reference carrier signal, whereby the reference carrier signal is continuously recovered across the boundary of the preamble and information word portions of the received signal; and d. phase detecting the received signal relative to the extracted reference carrier signals to demodulate the phase-modulated received signal.