Abstract: A method and system for monitoring a heating arrangement includes applying a first polarity voltage to a heater of the heating arrangement, detecting a first polarity heating leakage current, applying a second polarity voltage to the heating arrangement, detecting a second polarity heating leakage current, and determining health of the heating arrangement via the first polarity heating leakage current and the second polarity heating leakage current.

Abstract: A system and method for monitoring the health of a heater connected to a power supply by a power cable that includes a first power lead conducting an inlet current having an inlet current direction, and a second power lead conducting an outlet current having an outlet current direction opposite to the inlet current direction. The power cable passes through a center region of a toroid core one or more times, and a secondary winding on the toroid core is configured to induce a secondary voltage indicative of a difference between the inlet current and the outlet current, which defines the leakage current. The system includes a prognostic processor that is configured to calculate a heater health indication based on the secondary voltage, which is indicative of the heater health.

Abstract: Apparatus and associated methods relate to determining metrics of a cloud atmosphere using time difference measurements. A light projector projects a pulse of light into a cloud atmosphere, and a light sensor detects a portion of the projected pulse of light backscattered by the cloud atmosphere. A backscatter coefficient is calculated based on peak amplitude of the detected portion. An optical extinction coefficient is calculated based on a time difference between a peak time and a post-peak time, which correspond to times at which the peak amplitude of the detected portion occurs and at which the detected portion equals or crosses a sub-peak threshold, respectively. In some embodiments, a logarithm amplifier is used to facilitate processing of signals of widely varying amplitudes. In some embodiments, the sub-peak threshold is calculated as a fraction of the peak amplitude of the detected portion.

Abstract: A system and method for monitoring leakage current in a heater connected to a heater power supply by a power cable having a first power lead conducting an inlet current defining an inlet current direction and a second power lead conducting an outlet current defining an outlet current direction that is opposite the inlet current direction. The system includes a differential current electromagnetic sensor having a magnetic core with a center region that the power cable passes through one or more times. The magnetic core has an air gap in which a magnetic flux sensing device is positioned and configured to provide a signal that is representative of magnetic flux across the air gap, which is indicative of a difference between the inlet current and the outlet current. This difference defines the leakage current.

Abstract: A system and method for monitoring leakage current in a heater connected to a heater power supply by a power cable having a first power lead conducting an inlet current defining an inlet current direction and a second power lead conducting an outlet current defining an outlet current direction that is opposite the inlet current direction. The system includes a differential current electromagnetic sensor having a magnetic core with a center region that the power cable passes through one or more times. The magnetic core has an air gap in which a magnetic flux sensing device is positioned and configured to provide a signal that is representative of magnetic flux across the air gap, which is indicative of a difference between the inlet current and the outlet current. This difference defines the leakage current.

Abstract: A pressure sensor includes a MEMS pressure transducer with a pressure sensing diaphragm and sensor elements, an isolator diaphragm spaced apart from the pressure sensing diaphragm, and a ceramic header body. The ceramic header body has an electrical conductor and transducer aperture with the MEMS pressure transducer supported therein. The isolator diaphragm is coupled to the to the MEMS pressure transducer by a fluid and is sealably fixed to the ceramic body. The ceramic header body bounds the fluid and the electrical conductor electrically connects the MEMS pressure transducer with the external environment. Differential pressure sensors and methods of making pressure sensors are also described.

Abstract: A method and system for monitoring a heating arrangement includes applying a first polarity voltage to a heater of the heating arrangement, detecting a first polarity heating leakage current, applying a second polarity voltage to the heating arrangement, detecting a second polarity heating leakage current, and determining health of the heating arrangement via the first polarity heating leakage current and the second polarity heating leakage current.

Abstract: A system and method for monitoring the health of a heater connected to a power supply by a power cable that includes a first power lead conducting an inlet current having an inlet current direction, and a second power lead conducting an outlet current having an outlet current direction opposite to the inlet current direction. The power cable passes through a center region of a toroid core one or more times, and a secondary winding on the toroid core is configured to induce a secondary voltage indicative of a difference between the inlet current and the outlet current, which defines the leakage current. The system includes a prognostic processor that is configured to calculate a heater health indication based on the secondary voltage, which is indicative of the heater health.

Abstract: Apparatus and associated methods relate to determining metrics of a cloud atmosphere using time difference measurements. A light projector projects a pulse of light into a cloud atmosphere, and a light sensor detects a portion of the projected pulse of light backscattered by the cloud atmosphere. A backscatter coefficient is calculated based on peak amplitude of the detected portion. An optical extinction coefficient is calculated based on a time difference between a peak time and a post-peak time, which correspond to times at which the peak amplitude of the detected portion occurs and at which the detected portion equals or crosses a sub-peak threshold, respectively. In some embodiments, a logarithm amplifier is used to facilitate processing of signals of widely varying amplitudes. In some embodiments, the sub-peak threshold is calculated as a fraction of the peak amplitude of the detected portion.

Abstract: A MEMS device includes a backing wafer with a support portion and central back plate connected to the support portion with spring flexures, a diaphragm wafer with a support portions and a sensing portion connected to the support portion with spring flexures, a passivation layer on the diaphragm, and a topping wafer. The device allows for stress isolation of a diaphragm in a piezoresistive device without a large MEMS die.

Abstract: A pressure sensor includes a MEMS pressure transducer with a pressure sensing diaphragm and sensor elements, an isolator diaphragm spaced apart from the pressure sensing diaphragm, and a ceramic header body. The ceramic header body has an electrical conductor and transducer aperture with the MEMS pressure transducer supported therein. The isolator diaphragm is coupled to the to the MEMS pressure transducer by a fluid and is sealably fixed to the ceramic body. The ceramic header body bounds the fluid and the electrical conductor electrically connects the MEMS pressure transducer with the external environment. Differential pressure sensors and methods of making pressure sensors are also described.

Abstract: A MEMS device includes a backing wafer with a support portion and central back plate connected to the support portion with spring flexures, a diaphragm wafer with a support portions and a sensing portion connected to the support portion with spring flexures, a passivation layer on the diaphragm, and a topping wafer. The device allows for stress isolation of a diaphragm in a piezoresistive device without a large MEMS die.

Abstract: A MEMS device includes a backing wafer with a support portion and central back plate connected to the support portion with spring flexures, a diaphragm wafer with a support portions and a sensing portion connected to the support portion with spring flexures, a passivation layer on the diaphragm, and a topping wafer. The device allows for stress isolation of a diaphragm in a piezoresistive device without a large MEMS die.

Abstract: Apparatus and associated methods relate to generating redundant measurement of pseudo differential pressure using two absolute-pressure sensors, each exposed to a different environment. Each of the two absolute-pressure sensors has complementary first and second output nodes. The first output node has a positive relation with and/or response to increasing pressure, while the second output node has a negative relation with and/or response to increasing pressure. A first difference measurement signal is calculated based on a difference between the positive relation output signals of the first and second absolute-pressure sensors. A second difference measurement signal is calculated based on a difference between the negative relation output signals of the first and second absolute-pressure sensors. Both the first and second difference measurement signals are indicative of a pressure difference between the first and second environments.

Abstract: A sensor system includes a plurality of strain gauges and a passive compensation circuit. The plurality of strain gauges are configured to provide an output voltage indicative of a sensed pressure using an input voltage. The passive compensation circuit that includes a span resistor, first and second compensation resistors, and a zero offset resistor. The span resistor is connected between an input voltage and the pressure sensor and is configured to control a range of an output voltage for a pressure range of the pressure sensor. The first and second compensation resistors are operatively connected in parallel with the pressure sensor and are configured to control current provided to the pressure sensor. The zero offset resistor is operatively connected between the first and second compensation resistors and the pressure sensor and is configured to control a base value of the output voltage for zero pressure.

Abstract: A MEMS device includes a backing wafer with a support portion and central back plate connected to the support portion with spring flexures, a diaphragm wafer with a support portions and a sensing portion connected to the support portion with spring flexures, a passivation layer on the diaphragm, and a topping wafer. The device allows for stress isolation of a diaphragm in a piezoresistive device without a large MEMS die.

Abstract: Apparatus and associated methods relate to generating redundant measurement of pseudo differential pressure using two absolute-pressure sensors, each exposed to a different environment. Each of the two absolute-pressure sensors has complementary first and second output nodes. The first output node has a positive relation with and/or response to increasing pressure, while the second output node has a negative relation with and/or response to increasing pressure. A first difference measurement signal is calculated based on a difference between the positive relation output signals of the first and second absolute-pressure sensors. A second difference measurement signal is calculated based on a difference between the negative relation output signals of the first and second absolute-pressure sensors. Both the first and second difference measurement signals are indicative of a pressure difference between the first and second environments.

Abstract: A sensor assembly comprises a remote data concentrator (RDC) and an optically powered transducer module (OPTM). The RDC transmits a first optical pulse including a parameter request signal along an optical fiber. The OPTM is connected to the optical fiber, and comprises a photodiode, an energy storage device, a sensor, a processor, and a laser. The photodiode receives the first optical pulse, and the energy storage device is charged by the photodiode. The sensor, processor, and laser are powered by discharging the energy storage device. The sensor senses a parameter specified by the parameter request signal. The processor generates a signal packet from the output of the first sensor. The laser transmits a second optical pulse including the signal packet along the optical fiber to the RDC.

Abstract: A sensor assembly comprises a remote data concentrator (RDC) and an optically powered transducer module (OPTM). The RDC transmits a first optical pulse including a parameter request signal along an optical fiber. The OPTM is connected to the optical fiber, and comprises a photodiode, an energy storage device, a sensor, a processor, and a laser. The photodiode receives the first optical pulse, and the energy storage device is charged by the photodiode. The sensor, processor, and laser are powered by discharging the energy storage device. The sensor senses a parameter specified by the parameter request signal. The processor generates a signal packet from the output of the first sensor.

Abstract: A sensor system includes a plurality of strain gauges and a passive compensation circuit. The plurality of strain gauges are configured to provide an output voltage indicative of a sensed pressure using an input voltage. The passive compensation circuit that includes a span resistor, first and second compensation resistors, and a zero offset resistor. The span resistor is connected between an input voltage and the pressure sensor and is configured to control a range of an output voltage for a pressure range of the pressure sensor. The first and second compensation resistors are operatively connected in parallel with the pressure sensor and are configured to control current provided to the pressure sensor. The zero offset resistor is operatively connected between the first and second compensation resistors and the pressure sensor and is configured to control a base value of the output voltage for zero pressure.