Importance

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Abstract

A telemetering system wherein a transmitting device responsive to an input signal derived from a sensor representing a metered variable, such as temperature or flow rate, is adapted to generate a corresponding direct-current signal. This signal is conveyed over a two-wire line to a receiving station through a terminal resistor across which a voltage signal is developed corresponding to the incoming current signal. The receiving station includes a DC power supply whose output is fed over the same two-wire line to the transmitting device to provide operating power therefor. In order to enhance the power available to the transmitting device, the current signal generated by the transmitting device lies in a 0% to 100% signal range in which the ratio of direct-current I.sub.o at 0% signal to direct-current I.sub.100 at 100% signal is greater than 1/5 or 0.2. However, the voltage signal developed across the terminal resistor corresponds to the current signal and is converted to yield an output voltage signal in a 0% to 100% range in which the ratio of voltage V.sub.o at 0% signal to voltage V.sub.100 at 100% signal is equal to 1/5 or 0.2, thereby making it possible at the receiving station to operate receivers such as controllers and recorders which respond to an input voltage signal of this type.

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First Claim