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374 results about "Detection filter" patented technology

Cordless connection for a data/fax modem

A cordless modem comprises a radio pair interfaced to a standard data/fax modem which allows a user of a personal computer to wirelessly connect to a telephone line. One end of the radio pair is a remote unit interfaced to the modem contained within the PC while the other end is a base unit connected to a standard telephone wall jack. The base unit can selectively discriminate and adjust for signals received from a telephone voice handset or data signals received from the cordless modem remote unit. Upon receiving an off-hook signal or an incoming call signal, the base unit identifies the type of data (i.e., voice or computer modem data) and adapts accordingly by placing an FM modulator in either of a narrow band deviation or a wide band deviation covering the required range of the particular signal combined with local echo. That is, when voice data is present, a low deviation, narrow filter combination is selected. If, on the other hand, the computer data from the cordless modem is detected, a higher deviation, wider bandwidth filter is selected. In addition, the remote unit switches a pre-detection filter from one mode to another depending on whether it is connected to a computer modem or to a voice handset. Security from eavesdroppers as well as the mitigation of signal fading is provided by overlaying a pseudo-random number (PN) code on the FM modulated signal.
Owner:LENOVO (SINGAPORE) PTE LTD

Collaborative design method of fault detection filter and controller under DoS attack

The invention discloses a cooperative design method of fault detection filter and controller under DoS attack. The method is applied to a USV course control system, and is a cooperative design methodof a fault detection filter and an elastic event trigger controller based on a state observer, and the method comprises the following steps of: establishing a mathematical model based on the state observer USV control system under the influence of an actuator fault, a DoS attack and a network delay; introducing an event trigger mechanism related to the state of the observer, and establishing the model of the USV control system capable of simultaneously describing the time delay of the network transmission and the influence of the event trigger mechanism by using the time-delay system theory, determining an event trigger matrix W of the USV control system model, a state observer gain matrix L1, L2, a fault detection filter gain matrix V1, V2 and a controller gain matrix K; establishing a fault detection filter and an elastic event trigger controller based on a state observer under the DoS attack. The cooperative design method of fault detection filter and controller under DoS attack caneffectively resist the DoS attack and detect the fault in time.
Owner:NANJING UNIV OF POSTS & TELECOMM

High-precision gas concentration detection method and detection apparatus thereof

The invention discloses a high-precision gas concentration detection method and a detection apparatus thereof. The detection method comprises the following steps: a current is input to a laser drive circuit; a laser is driven by the laser driving circuit to emit a laser signal, and the laser signal passes through a detected gas in a gas chamber; a photoelectric detector receives a laser signal output by a relevant gas in the gas chamber after absorption, implements photoelectric detection, converts the laser signal to a voltage signal and inputs the voltage signal to a detection filter unit; a signal output by the detection filter unit implementing band-pass filter processing is divided into two paths, one path goes through a lock-in amplifier circuit to obtain a secondary harmonic signal, and the other path goes through an RMS conversion circuit to obtain an RMS signal; sampling is carried out, and the wave peak value Vpp max, the wave trough value Vpp min and the RMS are calculated; and a data processing unit calculates the concentration X of the gas to be detected. The gas concentration detection method can be used to accurately measure the concentration of the gas, and can eliminate the influences of a circuit and the change of light transmittance on the measurement of the concentration of the gas in order to improve the detection accuracy.
Owner:青岛励精海洋科技有限公司

Fault detection method of nonlinear network control system based on event triggering mechanism

ActiveCN108667673AIncreased failure sensitivityTroubleshooting fault detection issuesElectric testing/monitoringData switching networksEvent triggerSystem failure
The invention provides a fault detection method of a nonlinear network control system based on an event triggering mechanism, and relates to the technical field of network system fault detection. Themethod comprises the following steps: firstly, establishing a T-S fuzzy model of the nonlinear network control system, setting an event triggering condition, establishing a fuzzy fault detection filter model, establishing a fault weighting system, and then establishing a fault detection system model; selecting an appropriate residual evaluation function and a detection threshold according to the fault detection system model, and detecting whether a fault of the nonlinear network control system occurs; and finally, further designing a parameter matrix and an event triggering matrix of a fault detection filter according to the stability of the fault detection system and sufficient conditions of existence of the fault detection filter. By adoption of the fault detection method of the nonlinear network control system based on the event triggering mechanism provided by the invention, the robustness to external disturbance and communication delay is greatly improved, and the limited networkresources and computing resources can be saved by the application of the event triggering mechanism.
Owner:NORTHEASTERN UNIV
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