Abstract: 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.

Abstract: 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.

Abstract: Portable electronic devices and methods are presented for preserving the location of a vehicle, in which a geolocation of the portable electronic device is automatically obtained in response to detection of termination of a portable electronic device charging operation, allowing a user to locate a vehicle at which the charging operation was terminated.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An in situ flue gas analyzer includes a probe extendable into a flue. The probe has a measurement cell providing a signal responsive to a concentration of a gas within the flue. A controller is coupled to the probe and configured to provide an output based on the signal from the measurement cell. A first media access unit is coupled to the controller and is operably coupleable to a first process communication link. The first media access unit is configured to communicate in accordance with an all-digital process communication protocol. A second media access unit is coupled to the controller and is operably coupleable to a second process communication link. The second media access unit is configured to communicate in accordance with a second process communication protocol that is different than the all-digital process communication protocol. The first and second media access units are enabled simultaneously.

Abstract: 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.

Abstract: 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.

Abstract: A process gas analysis system is provided. The system includes a probe insertable into a source of process gas and having a distal end and a chamber proximate the distal end. A gas sensor is mounted within the chamber and is configured to provide an electrical indication relative to a species of gas. A diffuser is mounted proximate the distal end of the probe and is configured to allow gas diffusion into the chamber. A source of calibration gas is operably coupled to the probe and is configured to supply calibration gas, having a known concentration of the gas species. Electronics are coupled to the sensor and configured to store a pre-calibration process gas concentration and to measure an amount of time (sensor return time) for the sensor response to return to the pre-calibration process gas concentration. The electronics are configured to compare a measured sensor return time with a known-good sensor return time to provide an indication relative to the diffuser.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.