Device comprising a phase-locked loop, electronic apparatus...

Details Device comprising a phase-locked loop, electronic apparatus... Device comprising a phase-locked loop, electronic apparatus...

1998-06-22

2001-05-22

Chin, Stephen (Department: 2634)

Pulse or digital communications

Receivers

Angle modulation

C332S100000, C332S127000

Reexamination Certificate

active

06236689

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a frequency shift keying device having an input for frequency shift keying and a phase locked loop notably formed by:
a reference oscillator
a frequency-controlled oscillator having a frequency control input,
a phase detector for comparing the phase of the output signals of said controlled oscillator with those of the output of the reference oscillator.
The present invention relates to an electronic apparatus such as a mobile radio telephone comprising such a device.
The invention also relates to a method of frequency modulating an oscillator to which a phase-locked loop is added.
BACKGROUND OF THE INVENTION
The problem posed in a conventional frequency shift keying a device is that it is difficult to modulate the frequency of the carrier because of the fact that the control loop is opposed to any frequency variation.
This type of modulation is imposed on mobile radios which form part of a network that satisfies a prevailing NAMPS standard, notably on United States of America territory. This modulation is intended for the transmission of signaling data for the network.
SUMMARY OF THE INVENTION
The invention proposes a frequency shift keying device which lends itself well to a change of the carrier frequency for transmitting information.
Therefore, a frequency shift keying device is provided with a compensation circuit; for at least attenuating the phase locking during the periods of frequency shift keying.
The idea of the invention is based on the fact that the frequency modulation to be provided is considered a disturbance of the frequency of the oscillator and that a compensation is provided for destroying or for counteracting at least partly this disturbance to avoid the effect of servo control of the loop.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.


REFERENCES:
patent: 4538136 (1985-08-01), Drabing
patent: 4816782 (1989-03-01), Kunitomo et al.
patent: 4870384 (1989-09-01), Thomas
patent: 5130676 (1992-07-01), Mutz
patent: 5155454 (1992-10-01), Amoroso
patent: 5157358 (1992-10-01), Benson
patent: 0577323A1 (1994-01-01), None

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