A frequency measurement device includes a sampling unit that outputs a voltage sampling value in accordance with a voltage to be sampled and a sampling frequency; an single-cycle DFT angle shift computation unit that computes and outputs a first angle shift in accordance with the voltage sampling value; an multi-cycle DFT angle shift computation unit that computes and outputs a second angle shift in accordance with the voltage sampling value; a selection unit that selects and outputs one of the first and second angle shifts as a selected angle offset; a sampling frequency computation and outputting unit that computes a sampling frequency in accordance with the selected angle offset and outputs the same to the sampling module unit as a new sampling frequency; and a frequency measurement value computation and outputting unit that computes and outputs a frequency measurement value in accordance with the selected angle offset.

A frequency measurement device includes a sampling unit that outputs a voltage sampling value in accordance with a voltage to be sampled and a sampling frequency; an single-cycle DFT angle shift computation unit that computes and outputs a first angle shift in accordance with the voltage sampling value; an multi-cycle DFT angle shift computation unit that computes and outputs a second angle shift in accordance with the voltage sampling value; a selection unit that selects and outputs one of the first and second angle shifts as a selected angle offset; a sampling frequency computation and outputting unit that computes a sampling frequency in accordance with the selected angle offset and outputs the same to the sampling module unit as a new sampling frequency; and a frequency measurement value computation and outputting unit that computes and outputs a frequency measurement value in accordance with the selected angle offset.

Provided is a power supply abnormality detection circuit capable of detecting a power supply abnormality using a logic circuit.

The power supply abnormality detection circuit includes a preset first dividing circuit part dividing a frequency of an input clock signal by a frequency of a first ratio and output the divided frequency, a second dividing circuit part dividing a frequency of the input clock signal by the frequency of the first ratio when a power supply voltage is a normal voltage, and dividing a frequency of an input signal by a frequency of a second ratio different from the first ratio and outputting the divided frequency when the power supply voltage is an abnormal voltage, and a comparison circuit part performing comparison of two signals of an output signal of the first dividing circuit part and an output signal of the second dividing circuit part.

Apparatus and methods for determining an inertia characteristic of a synchronous area of an electric power grid are described. First data is determined. The first data represents a signal comprising a first variation in the grid frequency over a period of time, the signal resulting from a second variation, the second variation being a variation in provision of electric power to and/or consumption of electric power from the grid, the signal having been filtered according to a first filter defining a first frequency band to at least attenuate frequencies outside of the first frequency band. Second data is determined. The second data is representative of the second variation on a second frequency band, the second frequency band being substantially the same as the first frequency band. An inertia characteristic of a synchronous area of the electric power grid is determined based on the first data and the second data.

Apparatus and methods for determining an inertia characteristic of a synchronous area of an electric power grid are described. First data is determined. The first data represents a signal comprising a first variation in the grid frequency over a period of time, the signal resulting from a second variation, the second variation being a variation in provision of electric power to and/or consumption of electric power from the grid, the signal having been filtered according to a first filter defining a first frequency band to at least attenuate frequencies outside of the first frequency band. Second data is determined. The second data is representative of the second variation on a second frequency band, the second frequency band being substantially the same as the first frequency band. An inertia characteristic of a synchronous area of the electric power grid is determined based on the first data and the second data.

A C/N ratio detection circuit includes a voltage detector, an averaging section, a time variation range calculator, and a C/N ratio calculator. The voltage detector measures an input voltage of a signal. The averaging section calculates an average of the input voltage over a predetermined time. The time variation range calculator calculates a time variation range of the input voltage over the predetermined time. The C/N ratio calculator calculates a C/N ratio of the signal by using the average and time variation range of the input voltage.

A method and device for determining the location-dependent pulse responses in signal transmission from a transmitter in a transmission volume to a receiver in a reception volume, wherein either the transmitter or the receiver is a device fixed in a predetermined location and the other is a movable device includes: continuously emitting a band-limited signal by the transmitter; continuously capturing the signal and recording the signal with time indexing by the receiver; moving the movable device during the emission and capturing of the signal along a trajectory within the transmission or reception volume while continuously capturing the location coordinates of the movable device and recording the location coordinates with time indexing; and numerically solving a linear system of equations, the unknowns of which system of equations represent the pulse responses at discrete sampling points in the transmission or reception volume associated with the movable device.

The invention is directed to methods for radio frequency spectral analysis. Accordingly, flight instructions are executed on a first UAV to fly in a first flight pattern relative to a signal source. The first UAV detects radio signal(s) from the signal source and associated signal data. Flight instructions are concurrently executed on a second UAV to fly in a second flight pattern, relative to the first flight pattern of the first UAV. The second UAV also detects radio signal(s) from the signal source and associated signal data. The stored signal data from the drones may then be processed for visualization.

The invention is directed to methods for radio frequency spectral analysis. Accordingly, flight instructions are executed on a first UAV to fly in a first flight pattern relative to a signal source. The first UAV detects radio signal(s) from the signal source and associated signal data. Flight instructions are concurrently executed on a second UAV to fly in a second flight pattern, relative to the first flight pattern of the first UAV. The second UAV also detects radio signal(s) from the signal source and associated signal data. The stored signal data from the drones may then be processed for visualization.

In one implementation, a motor module according to the present invention includes: a motor driving circuit 10 to drive a motor M; and a position estimation device 30 to output an estimated position signal of a rotor R of the motor M. It also includes: a motor control circuit 20 to supply a command voltage value to the motor driving circuit 10 in response to a pulse signal; and a variable step-size memory 40 storing variable step-size information, which defines an amount of displacement of the rotor R per pulse of the pulse signal. The estimated position signal is an analog or digital signal. Upon receiving a pulse signal, the motor control circuit 20 determines the command voltage value based on an estimated position value of the rotor R acquired from the position estimation device 30 and the variable step-size information read from the variable step-size memory 40. The motor driving circuit 10 changes the position of the rotor R based on the command voltage value.