Methods, systems, and devices for coupling a modulated voltage signal to a current loop using a variable impedance bridge
AssigneeGeneral Electric Company
InventorsBruce Henderson, Alan Carroll Lovell
Life of this patent
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Abstract
A system for coupling a modulated voltage signal onto a current loop between a host device and a field device, in various embodiments, can include a circuit and an impedance bridge. The circuit is configured to flow current from the field device between two terminals of an input circuit in the host device, wherein the two terminals are included in the current loop. The impedance bridge is positioned between the two terminals and configured to modulate impedance to convert the current in a field loop produced by the field device into terminal voltage modulation, without introducing a DC voltage burden to the current.
Claims20
A method for coupling a modulated voltage signal onto a current loop between a host device and a field device, comprising:
- flowing current from the field device between two terminals of an input circuit of the host device, wherein the two terminals are included in the current loop;
- modulating a voltage signal provided at a voltage signal source of the host device;
- and
- modulating impedance using an impedance bridge to convert loop current into terminal voltage modulation, without introducing a DC voltage burden to the current, the impedance bridge including a first leg and a second leg, wherein the first leg has a higher impedance than the second leg, the impedance bridge having a variable output impedance that is controlled by the voltage signal source of the host device.
A system for coupling a modulated voltage signal onto a current loop between a host device and a field device, comprising:
- a circuit configured to flow current from the field device between two terminals of an input circuit of the host device, wherein the two terminals are included in the current loop;
- a voltage signal source configured to provide the modulated voltage signal;
- and
- an impedance bridge including a first leg and a second leg, wherein the first leg has a higher impedance than the second leg, the impedance bridge having a variable output impedance that is controlled by the voltage signal source, the impedance bridge is between the two terminals and is configured to modulate impedance to convert the current in a field loop produced by the field device into terminal voltage modulation, without introducing a DC voltage burden to the current.
An electronic device for coupling a modulated voltage signal from a host device to a current loop between the host device and a field device, comprising:
- a resistor included in the current loop and configured to form a voltage across its terminals in relation to a current flowing from the field device through the current loop;
- and
- an impedance bridge included in the current loop, the impedance bridge including a first leg and a second leg, wherein the first leg has a higher impedance than the second leg, the impedance bridge having a variable output impedance that is controlled by the modulated voltage signal, the impedance bridge is configured to modulate the impedance to convert the current in a field loop produced by the field device into terminal voltage modulation, without introducing a DC voltage burden to the current.
Dependencies are inferred from the claim text.