A measurement system and method tests for spurious emissions included in a signal transmitted from a mobile terminal in a shorter time than before. The system includes: a band division unit for dividing the measurement frequency band into a plurality of divided bands; a first spurious measurement control unit which causes a measurement device to measure the spurious emissions of the signal to be measured in each divided band and the peak power of the spear in each divided band; and a first pass/fail determination unit that determines whether or not pass determination criteria is satisfied. The first pass/fail determination unit determines whether the peak power does not exceed the threshold of the pass determination criteria in each divided band. The threshold value of the pass determination criteria is lower than the threshold of the standard determination criteria defined by the 3GPP standard.

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 includes an orthogonal coordinate signal generator that generates an orthogonal two-phase voltage signal from a three-phase voltage signal of three-phase alternating current power of a power system; 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. A prediction calculator calculates a predicted value of the angular frequency after a time has elapsed based on the angular frequency and a differential of the angular frequency. In a state in which the phase jump of the power system is not detected, the frequency calculator calculates the system frequency based on the angular frequency. When the phase jump of the power system is detected, the frequency calculator calculates the system frequency based on predicted value for a constant amount of time.

A system includes an orthogonal coordinate signal generator that generates an orthogonal two-phase voltage signal from a three-phase voltage signal of three-phase alternating current power of a power system; 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. A prediction calculator calculates a predicted value of the angular frequency after a time has elapsed based on the angular frequency and a differential of the angular frequency. In a state in which the phase jump of the power system is not detected, the frequency calculator calculates the system frequency based on the angular frequency. When the phase jump of the power system is detected, the frequency calculator calculates the system frequency based on predicted value for a constant amount of time.

A measurement data based method for identifying wind turbine generators which cause sub-synchronous oscillations in a complex power system has a theoretical foundation of the open-loop modal resonance and the parallel filter design. The advantages of the present invention are as follows. 1) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system using measurement data instead of parametric model. Hence, it simplifies the computation and reduces the modeling cost effectively. 2) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system precisely with reduced amount of measurement data, reducing the cost of hardware and data measurement effectively. 3) The present invention can identify the wind turbine generators which cause the SSOs in the complex power system based on the open-loop modal resonance theory.

The invention relates to a method for detecting high-frequency signals (22), comprising method steps as follows: dividing a high-frequency signal (22) into a raw signal (3) and a reference signal (4), attenuating the raw signal (3) into an attenuated signal (9), wherein the attenuating happens as a function of frequency of the raw signal (3) in accordance with an attenuation characteristic, rectifying the attenuated signal (9), so that a first direct voltage (15) is generated, rectifying the reference signal (4), so that a second direct voltage (16) is generated, ascertaining an attenuation from the ratio of the first and second direct voltages (15, 16), wherein the ratio corresponds to an attenuation factor for the attenuation of the raw signal (3), determining the frequency of the high-frequency signal (22) from the attenuation factor and an attenuation characteristic (17).

The invention relates to a method for detecting high-frequency signals (22), comprising method steps as follows: dividing a high-frequency signal (22) into a raw signal (3) and a reference signal (4), attenuating the raw signal (3) into an attenuated signal (9), wherein the attenuating happens as a function of frequency of the raw signal (3) in accordance with an attenuation characteristic, rectifying the attenuated signal (9), so that a first direct voltage (15) is generated, rectifying the reference signal (4), so that a second direct voltage (16) is generated, ascertaining an attenuation from the ratio of the first and second direct voltages (15, 16), wherein the ratio corresponds to an attenuation factor for the attenuation of the raw signal (3), determining the frequency of the high-frequency signal (22) from the attenuation factor and an attenuation characteristic (17).

The invention relates to a method for detecting a fault in an electrical network (1) through which an AC current flows, the method comprising a step of acquiring three samples (S.sub.1, S.sub.2, S.sub.3) of a sinusoidal signal (S) that is representative of the current flowing in the network (1), the acquisition of each sample being spaced apart by a fixed sampling time (T), a step of calculating an amplitude (A) of the signal (S), the calculation of the amplitude (A) depending solely on the three acquired samples (S.sub.1, S.sub.2, S.sub.3) and being independent of the sampling time (T), a step of determining a fault if the calculated amplitude (A) is above a first predetermined threshold or if the calculated amplitude (A) is below a second predetermined threshold.

The invention relates to a method for detecting a fault in an electrical network (1) through which an AC current flows, the method comprising a step of acquiring three samples (S.sub.1, S.sub.2, S.sub.3) of a sinusoidal signal (S) that is representative of the current flowing in the network (1), the acquisition of each sample being spaced apart by a fixed sampling time (T), a step of calculating an amplitude (A) of the signal (S), the calculation of the amplitude (A) depending solely on the three acquired samples (S.sub.1, S.sub.2, S.sub.3) and being independent of the sampling time (T), a step of determining a fault if the calculated amplitude (A) is above a first predetermined threshold or if the calculated amplitude (A) is below a second predetermined threshold.

A software-defined radiometer includes dual RF front end channels. One RF front end channel processes the horizontal polarization signals and the other RF front end channel processes the vertical polarization signals. Each RF front end channel includes a power splitter for splitting the polarization signals into a plurality of identical polarization signals, a filter bank of N-bandpass filters that have the same bandwidth but different center frequencies and a multi-input switch. The bandpass filters filter the horizontal and vertical polarization signals and provide a plurality of filtered horizontal and vertical polarization signals. A control circuit issues a control signal to the multi-input switch so as to route a desired one of the plurality of filtered horizontal and vertical polarization signals to a programmable frequency converter. The programmable frequency converter includes a programmable local oscillator that is configured to generate signals having any one of N frequencies and is used to produce intermediate frequency representations of the horizontal and vertical polarization signals. The intermediate frequency representations are converted into digital signals and processed to extract desired information and data.