Abstract: A method and apparatus for detecting at least two process variables in a loop powered circuit. The method includes the steps of (a) powering the loop, detecting a first process variable value during a first time interval, (b) detecting a second process variable value during a second time interval after the expiration of the first time interval, where the detected process variable values are represented by the magnitude of a current passing through the loop circuit.

Abstract: The invention is a method to detect a weak interface signal in a guided wave level measurement device. The device includes a waveguide, a signal generator and a signal receiver, the signal generator and signal receiver being operationally connected to the waveguide. The method includes the steps of transmitting an outgoing signal; monitoring the signal received at the signal receiver to detect a first signal level that exceeds or equals a first threshold level (TH1) and if such a signal level is detected, continue monitoring the received signal to detect a second signal level that exceeds or equals TH1. Finally, if a second signal level in excess of TH1 is detected, continue monitoring the received signal to detect a third signal level that exceeds or equals a second threshold level TH2.

Abstract: A controller that is linearly responsive to an input voltage provides continuously adjustable control of the width of a periodically repeating digital pulse, thereby achieving a linear voltage to duty-cycle ratio transfer function. The circuit of the present invention includes a master clock input, a ratio control voltage input, a controlled duty cycle clock output, a high gain amplifier configured as an integrator having differential inputs, each equipped with a low pass filter, a controlled current source, a resettable timing capacitor, a threshold detector and a reference pulse generator.

Abstract: A controller that is linearly responsive to an input voltage provides continuously adjustable control of the width of a periodically repeating digital pulse, thereby achieving a linear voltage to duty-cycle ratio transfer function. The circuit of the present invention includes a master clock input, a ratio control voltage input, a controlled duty cycle clock output, a high gain amplifier configured as an integrator having differential inputs, each equipped with a low pass filter, a controlled current source, a resettable timing capacitor, a threshold detector and a reference pulse generator.

Abstract: A controller that is linearly responsive to an input voltage provides continuously adjustable control of the width of a periodically repeating digital pulse, thereby achieving a linear voltage to duty-cycle ratio transfer function. The circuit of the present invention includes a master clock input, a ratio control voltage input, a controlled duty cycle clock output, a high gain amplifier configured as an integrator having differential inputs, each equipped with a low pass filter, a controlled current source, a resettable timing capacitor, a threshold detector and a reference pulse generator.

Abstract: A controller that is linearly responsive to an input voltage provides continuously adjustable control of the width of a periodically repeating digital pulse, thereby achieving a linear voltage to duty-cycle ratio transfer function. The circuit of the present invention includes a master clock input, a ratio control voltage input, a controlled duty cycle clock output, a high gain amplifier configured as an integrator having differential inputs, each equipped with a low pass filter, a controlled current source, a resettable timing capacitor, a threshold detector and a reference pulse generator.

Abstract: An improved magnetostrictive wire based position transducer that has applications in both liquid level measuring systems and in position indicating systems. A cylindrically structured and circularly polarized piezoelectric element directly measures the torsional acoustic waves in the magnetostrictive wire as they are received by the sensor. The cylindrical structure of the sensor eliminates many of the inadvertently detected acoustic and electrical pulses within the wire that are not indicative of the passage of the torsional wave of concern. The present system provides an improved sensor configuration which is selectively sensitive to torsional waves while being insensitive to vibrations in alternate planes. This improved piezoelectric sensor in combination with the electrical configuration allows placement of the magnetostrictive wire apart from the liquid whose level is being measured or from the indicator whose position is of concern.