A diagnostic system includes a fan control circuit coupled to an electric fan and a microcontroller, and a sense line coupled to the fan control circuit and the microcontroller. The fan control circuit outputs a fan command sense signal at a duty cycle through the sense line to the microcontroller. A tachometer generates a tachometer signal at a frequency indicative of the rotational speed of the electric fan. A fan tachometer circuit receives the tachometer signal and outputs the tachometer sense signal at a frequency to the microcontroller in response to the tachometer signal. The microcontroller sets a second diagnostic flag to an error value indicating that the sense line has impaired operation if the frequency of the tachometer sense signal is within a desired frequency range, and a first diagnostic flag is equal to a first error value.

A method, apparatus and computer program wherein the method comprises: identifying a plurality of extrema points in a detected biosignal; comparing the identified extrema points with a plurality of sets of reference points wherein different sets of reference points correspond to different frequencies of the biosignal; and identifying the set of reference points that most closely fit the identified extrema points to determine a frequency of the biosignal.

The present invention provides a deformation apparatus that deforms a surface of a member, the apparatus comprising: a plurality of actuators each of which is configured to apply a force to the member to deform the surface; a measurement device configured to measure an induced electromotive force generated in a first actuator of the plurality of actuators; and a controller configured to control the plurality of actuators, wherein the controller causes the measurement device to measure a temporal variation of an induced electromotive force in the first actuator while vibrating the member by using a second actuator, of the plurality of actuators, which is different from the first actuator, converts the measured temporal variation of the induced electromotive force into a frequency spectrum, and detects an abnormality in the first actuator based on the frequency spectrum.

The present invention provides a deformation apparatus that deforms a surface of a member, the apparatus comprising: a plurality of actuators each of which is configured to apply a force to the member to deform the surface; a measurement device configured to measure an induced electromotive force generated in a first actuator of the plurality of actuators; and a controller configured to control the plurality of actuators, wherein the controller causes the measurement device to measure a temporal variation of an induced electromotive force in the first actuator while vibrating the member by using a second actuator, of the plurality of actuators, which is different from the first actuator, converts the measured temporal variation of the induced electromotive force into a frequency spectrum, and detects an abnormality in the first actuator based on the frequency spectrum.

During frequency detection, a constant current source outputs an output current to charge a variable capacitor for multi-period. In a calibration mode, according to a comparison result between a cross voltage of the variable capacitor and a reference voltage, a capacitance value of the variable capacitor is adjusted. In a monitor mode, according to a reference frequency and the cross voltage of the variable capacitor, a frequency under test of a circuit under test is detected.

During frequency detection, a constant current source outputs an output current to charge a variable capacitor for multi-period. In a calibration mode, according to a comparison result between a cross voltage of the variable capacitor and a reference voltage, a capacitance value of the variable capacitor is adjusted. In a monitor mode, according to a reference frequency and the cross voltage of the variable capacitor, a frequency under test of a circuit under test is detected.

A system frequency detector includes an orthogonal coordinate signal generator generating an orthogonal two-phase voltage signal from a three-phase voltage signal of three-phase alternating current power of a power system by converting the three-phase voltage signal into a two-phase voltage signal orthogonal to the three-phase voltage signal, converting the two-phase voltage signal into a voltage signal of a rotating coordinate system, calculating a moving average of the voltage signal of the rotating coordinate system, and performing an inverse transformation of the voltage signal of the rotating coordinate system after calculating the moving average; and a frequency calculator including an angular frequency calculator calculating an angular frequency of the power system based on the two-phase voltage signal, and an arithmetic unit calculating a system frequency of the power system from the angular frequency, the frequency calculator further including a low-pass filter provided in series with the arithmetic unit.

A system frequency detector includes an orthogonal coordinate signal generator generating an orthogonal two-phase voltage signal from a three-phase voltage signal of three-phase alternating current power of a power system by converting the three-phase voltage signal into a two-phase voltage signal orthogonal to the three-phase voltage signal, converting the two-phase voltage signal into a voltage signal of a rotating coordinate system, calculating a moving average of the voltage signal of the rotating coordinate system, and performing an inverse transformation of the voltage signal of the rotating coordinate system after calculating the moving average; and a frequency calculator including an angular frequency calculator calculating an angular frequency of the power system based on the two-phase voltage signal, and an arithmetic unit calculating a system frequency of the power system from the angular frequency, the frequency calculator further including a low-pass filter provided in series with the arithmetic unit.

Embodiments described herein relate to a method for modifying transmission line characteristics. The method may include: making a first determination of a null frequency of an input signal to a transmission line; performing an analysis to make a second determination of a wavelength of the input signal using, at least in part, the null frequency; making a third determination, based on the analysis, of a half wavelength of the input signal; calculating, based on the half wavelength, a total stub length; and adding a trace to a stub associated with a via, wherein the stub and the trace are a length that is at least a portion of the half wavelength of the input signal.

Embodiments described herein relate to a method for modifying transmission line characteristics. The method may include: making a first determination of a null frequency of an input signal to a transmission line; performing an analysis to make a second determination of a wavelength of the input signal using, at least in part, the null frequency; making a third determination, based on the analysis, of a half wavelength of the input signal; calculating, based on the half wavelength, a total stub length; and adding a trace to a stub associated with a via, wherein the stub and the trace are a length that is at least a portion of the half wavelength of the input signal.