Device for transmission of information by pulse code frequency shift modulation
AssigneeCentre Electronique Horloger S.A.
InventorJean Fellrath
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Abstract
A device for transmission of information by pulse code frequency shift modulation. The device incorporates a phase-locked superheterodyne receiver including a single voltage controlled oscillator, and a demodulator including a phase comparator and a phase shifter. The intermediate frequency is equal to one half the input signal frequency shift. The comparator compares the phases of the intermediate frequency signal and of a signal of the same frequency derived from the voltage controlled oscillator to provide a message output.
Claims8
A device for receiving information by frequency shift keying, the received information being a binary input signal wherein two characteristic frequencies corresponding to the binary digits "O" and "I" are in a predetermined ratio, comprising a phase-locking superheterodyne receiver having only one local oscillator phase controlled by the input signal and a mixer for producing an intermediate signal frequency equivalent to half the shift of the input signal frequency, the said shift being defined by the difference between the two characteristic frequencies of the digits "O" and "I", and a demodulator formed by a phase detector coupled to receive the intermediate frequency signal and a signal of the same frequency obtained from the local oscillator, said phase detector determining whether, in balance, the phase between these signals is in the region of 0.degree. or 180.degree..
Dependencies are inferred from the claim text.