Abstract: A method and apparatus for processing a time domain reflectometry (TDR) signal having a plurality of reflection pulses to generate a valid output result corresponding to a process variable for a material in a vessel. The method includes the steps of determining a reference signal along a probe in the vessel, establishing a first fiducial reference point, a reference end of probe location, a measuring length and a maximum probe length. The method also includes the steps of periodically detecting a TDR signal along the probe, establishing a second fiducial reference point, a detected end of probe location, an end of probe peak to peak amplitude, and attempting to determine a process variable reflection on the TDR signal. The method indicates a broken cable condition, a loss of high frequency connection, a low amplitude reflection condition, an empty vessel condition.

Abstract: For electromagnetic wave distance measurement by the pulse transit time method, short electromagnetic transmission pulses are emitted at periodic transmission instants. The signals received in selected transmission cycles after the respective transmission instants are sampled for obtaining in each of these transmission cycles a sample at a sampling instant in a respective sampling time interval, each sampling instant having a delay dictated by a sampling function relative to the respective transmission instant. The sampling instants exhibit differing delays relative to the respective transmission instant so that the samples in sequence produce an image of the sampled received signal extended in time. The sampling function dictating the delays is generated by a computing circuit, preferably a microcomputer, thus making it possible to make use of any sampling function and to modify sampling of the received signals in any way.

Abstract: A method and apparatus for processing a time domain reflectometry (TDR) signal having a plurality of reflection pulses to generate a valid output result corresponding to a process variable for a material in a vessel. The method includes the steps of determining an initial reference signal along a probe, storing the initial reference signal as an active reference signal, periodically detecting a TDR signal along the probe in the vessel, and computing the output result using the TDR signal and the active reference signal. The method also includes the steps of determining an appropriate time for updating the active reference signal, automatically computing an updated reference signal at the appropriate time, and overwriting the active reference signal with the updated reference signal for use in subsequent computations of the output result.

Abstract: An apparatus and method for processing a time domain reflectometry (TDR) signal to generate an output result corresponding to a valid process variable. The method includes the steps of processing the TDR signal using at least two different techniques for detecting a valid reflection pulse generated by the process variable to calculate an independent result using each of the at least two techniques, and applying a weighted factor to the independent results from each of the at least two different techniques to provide weighted output results. The method also includes the steps of comparing the weighted output results, and selecting the valid output result from the weighted output results based on the comparing step. In the illustrated method, the comparing step includes the step of summing the weighted factors for each independent result.

Abstract: A sensor apparatus is provided for transmitting electrical pulses from a signal line into a vessel to measure a process parameter. The sensor apparatus includes a lower flange configured to be coupled to the vessel. The lower flange is formed to include a central aperture defined by a radially outwardly tapered surface located adjacent a top surface of the lower flange. The apparatus also includes a conductive probe element including a head having first and second radially outwardly tapered surfaces and an elongated conductive portion extending away from the head. The first tapered surface of the head is configured to engage the tapered surface of the lower flange to prevent movement of the probe element in a direction toward the lower flange. The apparatus further includes an upper flange configured to be coupled to the lower flange to secure the probe element to the lower flange.

Abstract: A mass flow meter is provided for measuring the mass flow rate of a material moving along a flow path. The mass flow meter generates a field of electromagnetic energy through which a material moving along the flow path passes. The mass flow meter includes a receiver that detects an amount of electromagnetic energy reflected from the material which is proportional to the concentration of material moving along the flow path. The amount of electromagnetic energy reflected and an assumed velocity are used to generate a response related to the mass flow rate of the material moving along the flow path.