Methods and devices suitable for monitoring the frequency of microwave tunable filters in real time. The frequency readout relies on the natural response of such a filter when excited by a pulse. Methods of measuring an operating frequency of a pole in a tunable filter include measuring a number of cycles in a natural response in the filter when the filter is excited by an electric current pulse, and determining a resonance frequency based on the number of cycles measured in the natural response. Such a method can provide the operating frequency information in a binary digital format, making it relatively easy to read and process. A measuring resonator may be mounted to the filter resonator and connected by a common actuator.

The present invention discloses a pulse frequency measurement device and method and a control system, the device including: a hardware counter configured to perform a counting operation on an input pulse sequence to output a counting result; and a processing unit configured to obtain number of pulses from the counting result outputted by the hardware counter and measure a first time period during which the obtained number of pulses occupy, in which the processing unit includes a frequency calculation module configured to calculate a frequency of the input pulse sequence based on the obtained number of pulses and the first time period. According to the invention, it is possible to achieve adaptive pulse frequency measurement and multi-channel sampling for multiple input pulse sequences with a relatively low cost while ensuring the accuracy of the measurement result.

The present invention discloses a pulse frequency measurement device and method and a control system, the device including: a hardware counter configured to perform a counting operation on an input pulse sequence to output a counting result; and a processing unit configured to obtain number of pulses from the counting result outputted by the hardware counter and measure a first time period during which the obtained number of pulses occupy, in which the processing unit includes a frequency calculation module configured to calculate a frequency of the input pulse sequence based on the obtained number of pulses and the first time period. According to the invention, it is possible to achieve adaptive pulse frequency measurement and multi-channel sampling for multiple input pulse sequences with a relatively low cost while ensuring the accuracy of the measurement result.

Disclosed are three methods for precise measurement of frequency deviation of known nominal frequency. Delta adder method (DA), comprising of delta-sigma modulator, delta-adder, delay line, low-pass filter, and zero crossing detector. The second method (DA+RE), comprising of delta-sigma modulator, circuit for squaring delta-sigma bit-stream, delta-adder, low-pass filter, and zero-crossing detector. The third method comprises of reference delta-sigma modulator for synchronization of two or more dislocated frequency sources of known nominal frequency.

A sound processing device performs obtaining a first frequency spectrum that corresponds to a first sound signal and a second frequency spectrum that corresponds to a second sound signal, calculating a level difference between a level of each of frequency components in the first frequency spectrum and a level of each of frequency components in the second frequency spectrum, calculating a spread of a distribution of the level difference during a prescribed period for each of the frequency components, and determining a gain to be multiplied to the frequency component in the first frequency spectrum and a gain to be multiplied to the frequency component in the second frequency spectrum in accordance with the spread of the distribution of the level difference.

An oscillation detector includes an amplitude variation detection circuit configured to generate a first pulse signal by comparing levels of voltages with each other, a frequency variation detection circuit configured to generate a second pulse signal by filtering the first pulse signal and allowing to pass a frequency component that is less than or equal to a certain frequency among frequency components of the first pulse signal, and a time variation detection circuit configured to output an oscillation detection signal when the second pulse signal has consecutive pulses for a period of time.

An oscillation detector includes an amplitude variation detection circuit configured to generate a first pulse signal by comparing levels of voltages with each other, a frequency variation detection circuit configured to generate a second pulse signal by filtering the first pulse signal and allowing to pass a frequency component that is less than or equal to a certain frequency among frequency components of the first pulse signal, and a time variation detection circuit configured to output an oscillation detection signal when the second pulse signal has consecutive pulses for a period of time.

A length measuring apparatus configured to perform length measurement for an object moving in a measurement region includes a detector configured to detect light modulated by the object with a Doppler effect, and a processor configured to obtain a measurement value of a velocity of the object based on a signal from the detector, and obtain a length for the object based on the measurement value. The processor is configured to specify a point in time corresponding to the object based on an amplitude of the signal, obtain the measurement value based on the signal with respect to a time duration defined by the point in time, and obtain the length based on the measurement value obtained with respect to the time duration.

An electronic magnetometer and a method for measuring a magnetic field are provided. A Gunn diode with magnetic shielding and a Gunn diode without magnetic shielding generate different induced high-frequency oscillating currents in various environments. The high-frequency oscillating current of the Gunn diode with magnetic shielding and the high-frequency oscillating current of the Gunn diode without magnetic shielding are processed by circuits and subsequently compared. The difference of frequencies in the two currents is proportional to the magnitude of magnetic field, and the magnitude of magnetic field is obtained.

An electronic magnetometer and a method for measuring a magnetic field are provided. A Gunn diode with magnetic shielding and a Gunn diode without magnetic shielding generate different induced high-frequency oscillating currents in various environments. The high-frequency oscillating current of the Gunn diode with magnetic shielding and the high-frequency oscillating current of the Gunn diode without magnetic shielding are processed by circuits and subsequently compared. The difference of frequencies in the two currents is proportional to the magnitude of magnetic field, and the magnitude of magnetic field is obtained.