Periodic digital signal samples of redundant sensed engine RPM signals are rejected for limit exceedance of known performance values, the nonrejected digital signal samples are each compared with a synthesized RPM equivalent signal to further reject any sample which differs from the synthesized value by more than a selected difference value, one of the nonrejected samples are then used for the engine RPM indication, and in the event that both samples are rejected the synthesized value is used.
A method for detection an alarm state of measurement signal values received by means for detecting measurement values, wherein an alarm state is triggered when for a currently received measurement signal value at least one pre-set limit value is exceeded, has a faster recognition of an alarm situation and at the same time a lower rate of false alarms when in a first step for measurement signal values which are subsequent in time their position parameter (2) and a corresponding deviation parameter (3) of the measurement signal values from the position parameter is calculated in an adjustable time window, wherein in a second step each further subsequent measurement signal value is compared to the position parameter (2) an weighted with the deviation parameter (3) in order to obtain a respective evaluation quantity, and wherein in a third step an outlier state (6) is detected when the evaluation quantity exceeds an adjustable outlier parameter, whereas an alarm state (8) indicating the presence of a significant drift or jump of the measurement signal values is detected when the evaluation quantity exceeds an adjustable alarm parameter.
The sensor malfunction detection system for a gas-turbine engine is configured to determine or check once every first predetermined time period whether the outputted value from the sensor is within a permissible range and determines that the sensor is faulty when the result of the check is at least one result between the case of the number of times the outputted value is found not to be within the permissible range exceeding a first predetermined value and the case of the number of times the outputted value is consecutively found not to be within the permissible range exceeding a second predetermined value. Since the system discriminates whether the total number of times the sensor output is found to be outside the permissible range is fewer than the first predetermined value, it can avoid erroneous detection of transient abnormalities caused by noise or the like as sensor malfunction, and since it discriminates whether the number of times the sensor output is consecutively found not to be within the permissible range is fewer than the second predetermined value, it can promptly detect sensor malfunction owing to wire breakage or the like. The system can therefore detect sensor malfunction with good accuracy using a simple configuration.
A method and system by which the number of samples used to characterize the noise cycle of an active noise cancellation system varies dynamically as a function of the fundamental operating frequency of the system.
A ratiometric converter receives an external sense signal and external reference signal and provides an output signal which is proportional to the sense signal and inversely proportional to the reference signal. Electromagnetic interference and noise coupled onto the sense and reference lines are effectively removed by converting the sense signal to a digital signal and converting the reference signal to a digital signal. The digital sense signal is then filtered through a low pass filter to provide a filtered signal, and similarly, the digital reference signal is filtered through a low pass filter to provide a filtered digital reference signal. A divider circuit then divides the filter digital sense signal by the filter digital reference signal to provide the output signal.
A method and apparatus to estimate slopes accurately, as well as to eliminate slope estimation errors, taking error generating conditions into account. The slope on which the vehicle is running is estimated from the vehicle speed and the engine rpm value. The result is entered to the slope estimation unit through a low pass filter, then to the navigation unit. A noise eliminator is provided to the output of the slope estimation unit so that noises can be eliminated, for example, during gear-shifting or for a certain time after the gear shifting is completed by obtaining the "gear shifting" information from the automatic transmission control. The preceding estimated slope value is held during the noise elimination period.
