Abstract: A guided wave radar transmitter for interface measurement comprises a probe defining a transmission line for sensing level of two immiscible liquids to define an interface therebetween. A pulse circuit generates pulses on the transmission line and receives a reflected signal from the transmission line. The reflected signal selectively includes a level pulse representing material level and an interface pulse representing interface level. A controller operates in an interface mode to determine the material level and the interface level responsive to receiving the level pulse and the interface pulse. The controller operates in a medium identification mode responsive to not receiving the interface pulse, comprising calculating an estimated amplitude of the level pulse for the two immiscible liquids and comparing actual amplitude of the level pulse to the estimated amplitude of the level pulse to identify the medium in the vessel.

Abstract: A guided wave radar level measurement instrument comprises a probe defining a transmission line for sensing material level. A pulse circuit is connected to the probe for generating pulses on the transmission line and receiving reflected signals from the transmission line. The pulse circuit comprises a pulse generator for generating a transmit pulse, a bridge circuit having a diode switched front end connected between the pulse generator and a differential circuit. The transmission line is connected to one side of the differential circuit. Generated pulses from the pulse generator are supplied to both sides of the differential circuit and reflected signals from the transmission line are supplied to one side of the differential circuit.

Abstract: A guided wave radar level measurement instrument comprises a probe defining a transmission line for sensing material level. A probe interface circuit is connected to the probe for generating pulses on the transmission line and receiving reflected signals from the transmission line. The probe interface circuit comprises a transmit pulse generator for generating a transmit pulse, a sample pulse generator for generating a sample pulse, and a delay lock loop for controlling the transmit and sample pulse generators. The delay lock loop is controlled by a pulse repetition frequency having a duty cycle less than 50%.

Abstract: A probe for use with a measurement instrument includes a circuit connected to the probe. The probe comprises a process adaptor for mounting to a process vessel and including a through bore extending from a connector end to a process end. A counterbore at the connector end defines a shoulder. A support assembly is received in the counterbore and rests on the shoulder. The support assembly comprises an annular rod support having a through opening with a tension rod extending through the opening and secured at opposite sides of the annular rod support. A locking nut secures the support assembly in the counterbore to maintain the annular rod support in compression. A probe rod extends from a process end of the tension rod. A seal assembly is operatively secured to the process adaptor at the connector end with the seal pin in electrical contact with a connector end of the tension rod.

Abstract: A process measurement instrument includes a fiducial and is adapted for detection of the fiducial. The instrument includes an interface circuit comprising a drive circuit for transmitting a pulse signal at the fiducial and at a target of interest and a receive circuit receiving reflected echoes of the pulse signal and developing an analog receive signal representative of the reflected echoes. A processing circuit is operatively coupled to the interface circuit for receiving the analog receive signal and comprising a threshold detector detecting if the analog receive signal is above a select threshold value. A controller is operatively coupled to the processing circuit and responsive to leading and trailing edges of the reflected echo for the fiducial and determining an average of the leading and trailing edges to determine location of the fiducial.

Abstract: A process measurement instrument including a fiducial and adapted for detection of the fiducial. The instrument comprises an interface circuit comprising a drive circuit for transmitting a pulse signal at the fiducial and at a target of interest and a receive circuit receiving reflected echoes of the pulse signal and developing an analog receive signal representative of the reflected echoes. A signal processing circuit is operatively coupled to the interface circuit for receiving the analog receive signal and determining characteristics of reflected echoes for the fiducial and the target of interest. The controller is operatively coupled to the signal processing circuit and includes a diagnostic routine responsive to the characteristics of the reflected echo for the fiducial in determining if a fiducial error condition exists.

Abstract: A probe for use with a measurement instrument includes a circuit connected to the probe. The probe comprises a process adaptor for mounting to a process vessel and including a through bore extending from a connector end to a process end. A tubular body is received in the process adaptor at the connector end and has an outer diameter less than an inner diameter of the process adaptor at the connector end to define a cavity therebetween. The cavity is open to the process vessel. A coupling secures the body to the process adaptor. A center conductor is coaxial with the tubular body and the process adaptor. A seal element is disposed between the tubular body and the center conductor. Process pressure in the process vessel increases compressive force between the tubular body and the seal element.

Abstract: A loop powered process instrument comprises a control system measuring a process variable and developing a measurement signal representing the process variable. An output circuit, for connection to a remote power source using a two-wire process loop, controls current on the loop in accordance with the measurement signal. A power supply is connected to the output circuit and the control system. The power supply receives power from the two wire process loop and supplies power to the control system. The power supply comprises a voltage regulator receiving loop power and developing a regulated output voltage and an adjustable shunt regulator controlling voltage supplied to the voltage regulator.

Abstract: A probe defining a transmission line is used with a measurement instrument including a pulse circuit connected to the probe for generating pulses on the transmission line and receiving reflected pulses on the transmission line. The probe comprises an adapter for mounting to a process vessel. A conductive outer sleeve is secured to the adapter. A center conductor is coaxial with the outer sleeve for conducting the pulses. The conductive outer sleeve has a connector end proximate the adapter and a distal end to extend into a processed liquid. The outer sleeve has a geometric discontinuity defining a referenced target producing an impedance change at a position between the adapter and the distal end at a location in a process vapor region above a processed liquid.

Abstract: A probe defining a transmission line for use with a measurement instrument includes a pulse circuit connected to the probe for generating pulses on the transmission line and receiving reflected pulses on the transmission line. The probe comprises a conductive outer sleeve for mounting to a process vessel. A center conductor is coaxial with the outer sleeve for conducting the pulses. A primary seal element between the outer sleeve and the center conductor is spaced a select distance from a near end of the outer sleeve. A secondary seal element between the outer sleeve and the center conductor is spaced proximate the near end of the outer sleeve, to define a generally tubular space between the primary seal element and the secondary seal element. A dielectric insert fills a portion of the tubular space proximate the secondary seal element. A leak detection tube is in the tubular space between the dielectric insert and the primary seal element.

Abstract: A guided wave radar transmitter for interface measurement comprises a probe defining a transmission line for sensing level of two immiscible liquids to define an interface therebetween. A pulse circuit generates pulses on the transmission line and receives a reflected signal from the transmission line. The reflected signal selectively includes a level pulse representing material level and an interface pulse representing interface level. A controller operates in an interface mode to determine the material level and the interface level responsive to receiving the level pulse and the interface pulse. The controller operates in a medium identification mode responsive to not receiving the interface pulse, comprising calculating an estimated amplitude of the level pulse for the two immiscible liquids and comparing actual amplitude of the level pulse to the estimated amplitude of the level pulse to identify the medium in the vessel.

Abstract: A radar transmitter for emulsion measurement comprises a probe defining a transmission line for sensing impedance. A pulse circuit is connected to the probe for generating pulses on the transmission line and receiving a reflected signal from the transmission line. The reflected signal comprises a waveform of probe impedance over time. A controller is operatively connected to the pulse circuit. The controller profiles content of the emulsion responsive to the waveform by transforming the waveform into impedance relative to distance, converting the transformed waveform into effective dielectric relative to distance, determining mixture content of the emulsion at select distances responsive to the effective dielectric at the select distances and developing an output representing mixture content relative to level units.

Abstract: A measurement instrument comprises a sensor circuit comprising a drive circuit for transmitting a pulse signal at a target of interest and a receive circuit receiving reflected echoes of the pulse signal and developing an analog signal representative of the reflected echoes. An analog processing circuit is operatively coupled to the sensor circuit for receiving the analog signal and comprising a gate for selectively transferring the analog signal to a comparator that compares the gated analog signal to a select threshold level to develop a data signal representative of location of the target of interest. A programmed digital processing circuit is operatively coupled to the sensor circuit and the analog processing circuit and comprises a measurement module to control the drive circuit and evaluate the data signal to determine material location.

Abstract: A process measurement instrument with target rejection comprises a sensor circuit. The sensor circuit comprises a drive circuit for transmitting a pulse signal at a target of interest and a receive circuit receiving reflected echoes of the pulse signal and developing an analog receive signal representative of the reflected echoes. An analog processing circuit receives the analog receive signal and comprises a summer subtracting an analog target rejection signal from the analog receive signal to develop a corrected receive signal. A programmed digital processing circuit is operatively coupled to the analog processing circuit and comprises a memory storing target rejection signal value data representing false target reflections and developing the analog target rejection signal for transfer to the analog processing circuit.

Abstract: There is disclosed a process instrument comprising a housing and an antenna secured to the housing. A process adaptor is associated with the antenna and housing for securing the instrument to a process vessel to define a process seal. A control in the housing generates or receives a high frequency signal. The control comprises an electromagnetic radiating element. A body supports the radiating element in the housing proximate the antenna for rotation at any angular orientation without affecting the process seal.

Abstract: A time domain reflectometry measuring instrument uses a microprocessor that provides added functionality and capabilities. The circuit electronics and probe are tested and calibrated at the factory. Installation and commissioning by the user is simple. The user installs the probe. The transmitter is attached to the probe. The user connects a standard shielded twisted pair to the electronics. Power is applied and the device immediately displays levels. A few simple parameters may need to be entered such as output characteristics and the process material dielectric constant.

Abstract: A guided wave radar measurement instrument comprises a probe defining a guided wave radar transmission line. A pulse circuit is connected to the probe for generating a very fast stream of pulses on the transmission line and receiving reflected pulses returned on the transmission line. The reflected pulses represent a characteristic of a material being measured. An equivalent time sampling circuit is connected to the pulse circuit operable to sample reflected pulses to build a time multiplied picture of the reflected pulses and comprises a ramp generator circuit generating a saw tooth ramp signal used to selectively delay sampling reflected pulses to build the time multiplied picture. In one aspect of the instrument, the saw tooth ramp signal has a controlled ramp start for each cycle and retrace at an end of the cycle.

Abstract: A time domain reflectometry measuring instrument uses a microprocessor that provides added functionality and capabilities. The circuit electronics and probe are tested and calibrated at the factory. Installation and commissioning by the user is simple. The user installs the probe. The transmitter is attached to the probe. The user connects a standard shielded twisted pair to the electronics. Power is applied and the device immediately displays levels. A few simple parameters may need to be entered such as output characteristics and the process material dielectric constant.

Abstract: A guided wave radar probe defines a transmission line for use with a measurement instrument including a pulse circuit connected to the probe for generating pulses on the transmission line and receiving reflected pulses on the transmission line. The probe includes a center conductor for conducting the pulses. A conductive outer sleeve is coaxial with the center conductor. The conductive outer sleeve has a process end and a connector end. The process end is exposed, in use, to a process environment being measured. A first cylindrical seal element between the center conductor and the outer sleeve is at the sleeve process end. The first cylindrical seal element is of a first material adapted to withstand a relatively high temperature. A second cylindrical seal element is between the center conductor and the outer sleeve disposed between the first cylindrical seal element and the connector end.

Abstract: A capacitance point level switch includes a probe adapted to be disposed in a material containing vessel, the material having a capacitance value dependent upon its level in the vessel. An oscillator circuit develops a periodic signal at a select frequency. A reference network is driven by the oscillator and includes a reference capacitance for developing a periodic reference signal at the select frequency and phase displaced responsive to the reference capacitance. A probe network is driven by the oscillator and is connected to the probe to include the capacitance of the material for developing a periodic probe signal at the select frequency and phase displaced responsive to capacitance of the material. An output circuit is connected to the reference network and the probe network for developing a discrete output assuming a first or a second state according to the relative phase displacement of the periodic reference signal and the periodic probe signal.