4 results about "Measurement frequency" patented technology

The application relates to the technical field of acoustic measurement, and particularly provides a low-frequency acoustic parameter measurement method and device. The method comprises the following steps: acquiring a first measurement sound pressure corresponding to a first cavity and a second measurement sound pressure corresponding to a second cavity under a first measurement condition; the first cavity and the second cavity are separated by an excitation piece; the first measurement condition comprises that the first cavity and the second cavity are isothermal; the measurement frequency range of the first cavity and the second cavity is a first target low-frequency frequency range; and a sample to be measured is arranged in the first cavity; a first sound pressure transfer function is obtained by calculating according to the first measurement sound pressure and the second measurement sound pressure; and a target acoustic parameter corresponding to the sample to be measured is obtained by calculating according to the first sound pressure transfer function, a first volume of the first cavity and a second volume of the second cavity. The low-frequency acoustic parameter measurement method and device accurately and efficiently obtain the target acoustic parameter of the sample to be measured under the isothermal low-frequency condition.

The invention relates to a method for configuring a photoacoustic chamber unit and to a photoacoustic chamber unit that comprises a resonator (30) defining an interior space (31), and at least one acoustic detector (15) adapted for detecting sound waves generated in a medium contained in the interior space (31). One of the modes that are generated in the interior space (31) and being defined by the geometry of the interior space (31) and the acoustic measurement frequency is selected as a measurement mode, and, if there is another disturbing mode that overlaps with it, then an opening (39) or openings (39) are formed for the selective and relative damping of the interfering mode at certain locations in the wall of the resonator (30).

This invention discloses a switchable dual-clamp unit measurement system for multi-branch grounding systems, comprising multiple isomorphic dual-clamp units. Each dual-clamp unit can clamp a branch and has mode switching capabilities: In non-target branch measurement mode, the single-frequency response of the measurement frequency is extracted based on the feedback signal of the measurement clamp, and test signals with the same amplitude but opposite phase are injected into the pressure clamp in stages to obtain the feedback phase difference; combined with the feedback phase difference, the phase of the injected signal is calculated based on the residual response phasor at the current branch measurement frequency, and the injection amplitude is adjusted to make the residual amplitude index converge and meet the threshold to achieve non-target branch isolation. In target branch measurement mode, a measurement excitation is applied at the measurement frequency to extract the response coefficient, and the grounding resistance value is calculated and output based on the excitation and response. This invention does not require explicit calibration of the channel phase delay, and each dual-clamp unit can work in parallel at the same frequency without coordinated communication, making it particularly suitable for non-disconnection measurement deployments in multi-branch, large-span fields.

A method comprises receiving an input clock signal having a clock frequency band between a lower frequency limit value and an upper frequency limit value, dividing the clock frequency band in a set of frequency ranges having a set of frequency limit values that include the lower frequency limit value and the upper frequency limit value, comparing the frequency of the clock signal with the set of frequency limit values to produce comparison indicators having a first logic value when the measured frequency fails to exceed at least one frequency limit value and having a second logic value when the measured frequency exceeds the at least one frequency limit value, and, as a result of at least one of the logic values of comparison indicators having the second logic value, producing a global flag signal indicating that the measured frequency falls outside of a frequency range.