Elsag International N.v.

Rosemount Analytical Inc.

Rosemount Inc.

Nemer, Joseph C.

Joseph C Nemer

Mark D Stojkov

Tourang Birangi

Douglas Evan Simmers

James D Kramer

Richard J Molnar

Pierre C Bertrand

Brian D Hemphill

Anni S Wey

Mark W Schneider

Douglas E Simmers

A probe gas analysis system is provided. The probe gas analysis system comprises a probe body configured to be exposed to a source of process gas. The probe gas analysis system also comprises a sensor cell assembly having a sensor cell with a sensing side and a reference side. The sensing side is disposed to contact the source of process gas, and to generate a signal indicative of a detected difference in oxygen concentration between the reference side and the sensing side. The probe gas analysis system also comprises a substantially permanent seal coupling the sensor cell assembly to the probe body, wherein the substantially permanent seal separates the reference side from the sensing side.

Oxygen sensing probe/analyzer

A process combustion transmitter is provided. The transmitter includes a process probe extendible into a flow of process combustion exhaust. The process probe has a measurement cell with an operating temperature that is above a flashpoint of process combustion fuel. The process probe includes a heater configured to heat the measurement cell to the operating temperature. Electronic circuitry is coupled to the measurement cell and to the heater. The electronic circuitry is configured to disengage power to the heater once process combustion heat is sufficient to maintain the measurement cell at the operating temperature and thereafter to maintain the heater in a de-energized state.

Method of operation an in SITU process probe

An in situ oxygen analyzer having an intrinsically-safe output and a heated probe is provided. The probe is extendable into a source of process gas and has an oxygen sensor and heater disposed therein. The heater is configured to heat the oxygen sensor to a temperature sufficient to operate the oxygen sensor. A housing is coupled to the probe and has first and second chambers. The first chamber is explosion-rated and includes non-intrinsically safe circuitry coupled to the heater to energize the heater. The second chamber contains only intrinsically-safe circuitry that complies with an intrinsically-safe specification. The first and second chambers are isolated from one another. The non-intrinsically-safe circuitry is coupled to the intrinsically-safe circuitry through an energy-limiting isolator.

In situ heated oxygen probe with intrinsically safe output

A process combustion transmitter is provided. The transmitter includes a process probe extendible into a flow of process combustion exhaust. The process probe has a measurement cell and a diffuser that define a chamber within the process probe. Electronic circuitry is coupled to the measurement cell and is configured to provide an indication relative to a combustion process based on an output signal of the measurement cell. A pressure sensor is coupled to the electronic circuitry and is fluidically coupled to the chamber. The electronic circuitry is configured to provide an adjusted calibration based on pressure measured within the chamber during a calibration.

In situ probe with improved diagnostics and compensation

Oxygen sensing probe

A FSK demodulator which uses the combination of a digital phase comparator and a digital controlled oscillator (DCO) in the form of a state machine to demodulate an FSK signal. The phase comparator compares the phase of the FSK signal with the output of the DCO to provide a signal to the DCO having a level dependent on the phase relationship between the two signals at the input to the comparator. The demodulator also includes a filter to obtain the data from the signal at the output of the comparator.

Digital FSK demodulator

A signal isolating device for an input digital signal has a first photo-coupler which is activated by the differential pulse produced at the leading edge of the digital signal and a second photo-coupler which is activated by the differential pulse produced at the trailing edge of the digital signal. A positive feedback system is connected in push-pull fashion with the photo-couplers for producing an output digital signal that corresponds to the input digital signal. The positive feedback system may be implemented by a buffer that includes a resistor for keeping the buffer in a stable state even when both of the photo-couplers are non-conductive.

Low power digital signal isolator

A digital implementation for a carrier detector. The detector determines if the carrier frequency at any instant is within a predetermined frequency band. The detector further determines if the detected frequency remains within the predetermined frequency band for a predetermined period of time. The detector also provides an indication that there has not been any loss of carrier for another predetermined period of time.

Method and apparatus for performing carrier detection

A FSK modulator which uses the combination of a state machine and a toggle flip-flop to generate the FSK signals. The state machine has a loop having a predetermined number of states. The number of clock cycles that the state machine takes to traverse the loop depends on the state or level of the signal at the input to the modulator. The flip-flop converts the state machine output signal to a signal having a rectangular waveform.

Digital FSK modulator

A method and apparatus for increasing the resolution of a pulse width modulated signal representative of a measured parameter such as the pressure measured by a pressure cell. The analog signal from the pressure cell is converted to a digital signal using a predetermined clock frequency. The digital signal is scaled to 2.sup.N (N is an integer greater than or equal to one) times the clock frequency and the N lowest order bits are checked to determine if they are a one or a zero. A one is added to the least significant bit of the scaled digital signal in a predetermined manner in the next N consecutive cycles of the scaled digital signal dependent upon the which of the N lowest order bits are a one.

Method and apparatus for increasing the resolution of a digital to

A method for compensating for the differences in temperature across a cell used to sense pressure. A microprocessor calculates a dynamic temperature factor signal by multiplying a signal representative of temperature change across the cell by a coefficient based on measurements made of the effect of temperature change on the cell. The dynamic temperature factor signal is then subtracted from the signal representative of the differential pressure sensed by the cell to thereby provide the dynamic temperature compensation.

Dynamic temperature compensation for a pressure cell

A method for filtering digital signals in a pressure transmitter. The transmitter includes a microprocessor. In each operating cycle of the microprocessor included in the transmitter, the method determines if there are any noise spikes in the signal at the input to the microprocessor representative of pressure and provides rejection for such spikes. The method also provides for a faster response to a step change in pressure than is provided by conventional filtering methods and also dampens small fluctuations in the filtered output signal.

Growing community of inventors

Mayfield Heights, OH, United States of America

Joseph C Nemer