Pulse or digital communications – Systems using alternating or pulsating current – Angle modulation
Reexamination Certificate
2008-05-13
2008-05-13
Ahn, Sam K. (Department: 2611)
Pulse or digital communications
Systems using alternating or pulsating current
Angle modulation
Reexamination Certificate
active
07372914
ABSTRACT:
Improved control apparatus and methods transfer information between devices, such as controllers and field devices, utilizing a modulator that generates a pulse width modulated (PWM) signal containing information to be transferred by a first of the devices, e.g., the controller, to the second device. A transformer or other inductive device transfers the PWM signal across the isolation barrier, where it is demodulated to analog form for application to the second device, e.g., the field device. Information transferred from the second device to the first device can be transferred in an amplitude modulated (AM) signal that utilizes, as its carrier, a fixed duty cycle output of the modulator that generates the PWM signal.
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Ahn Sam K.
Invensys Systems Inc.
Nutter & McClennen & Fish LLP
Powsner David J.
Shen Charlton
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