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322results about How to "High frequency resolution" patented technology

Tempo detection apparatus, chord-name detection apparatus, and programs therefor

There is provided a tempo detection apparatus capable of detecting, from the acoustic signal of a human performance of a musical piece having a fluctuating tempo, the average tempo of the entire piece of music and the correct beat positions, and further, the meter of the musical piece and the position of the first beat.
The tempo detection apparatus includes an input section 1 for receiving an acoustic signal; a chromatic-note-level detection section for applying an FFT calculation to the received acoustic signal at predetermined time intervals to obtain the level of each chromatic note at each of predetermined timings; a beat detection section 2 for summing up incremental values of respective levels of all the chromatic notes at each of the predetermined timings, to obtain the total of the incremental values of the levels, indicating the degree of change of entire sound at each of the predetermined timings, and for detecting an average beat interval and the position of each beat from the total of the incremental values of the levels; and a measure detection section 3 for calculating the average level of each chromatic note for each beat, for summing up incremental values of respective average levels of all the chromatic note for each beat to obtain a value indicating the degree of change of entire sound at each beat, and for detecting a meter and the position of a measure line from the value indicating the degree of change of entire sound at each beat.
Owner:KAWAI MUSICAL INSTR MFG CO

System and method for measuring time-sharing quick steady-state sine sweep excitation frequency response function

InactiveCN101561342AEasy to operateLarge excitation powerVibration testingShielded cableData acquisition
The invention relates to a system and a method for measuring time-sharing quick steady-state sine sweep excitation frequency response function, which belong to the technical field of vibration tests. An excitation system adopts a vibration exciter and a power amplifier. A force sensor and a vibration sensor are adopted to measure an exciting force signal and a vibratory response signal of the system at the same time. A charge amplifier is adopted to condition and filter the signals. A data acquisition system connects a data acquisition card with a connecting terminal through a high-performance shielded cable and is connected with a general computer to acquire and send data. The generation of a sweep signal and the data processing, analysis, storage and display of an exciter response signal are achieved by adopting software based on the general computer. The system and the method achieve quick steady-state sine sweep excitation, the complete cycle sampling of the exciter response signal, and precise and reliable frequency response function curve. The test system is guided by computer programs and is finished automatically, the test method is precise and reliable, and the system and the method have important meaning on testing the dynamic properties of structural elements.
Owner:BEIJING UNIV OF TECH

A Method for Measuring Grid Voltage Flicker

The invention discloses a method for measuring electric network voltage flicker, and discloses a high-accuracy rapid flicker calculating method aiming at a non-integral cycle low sampling rate by taking account of errors probably caused by harmonic waves and electric network frequency. The core of the calculating method is that: a low fixed sampling rate is adopted to perform non-integral cycle sampling on electric network voltage waveforms, a cosine window is used for performing a fast Fourier transform algorithm (FFT), then the flicker frequency component is accurately extracted through a double-spectral line interpolation algorithm and a frequency spectrum searching algorithm, and the instantaneous flicker visual sensitivity is obtained through calculation. By using the method, under the condition of non-integral cycle low sampling rate, the errors caused by frequency spectrum leakage and harmonic wave aliasing are overcome, the frequency resolution is improved, the complexity of flicker calculation is effectively simplified, and a flicker measurement result is acquired quickly. By using the method, the performance requirement of hardware of an analog-digital converter, a processor and the like is reduced, thus the cost of a flicker measuring instrument is reduced, and simultaneously the measuring accuracy is improved; and besides, the method is applicable to fast low-cost measurement of the electric network voltage flicker, and has a very good effect.
Owner:SUZHOU UNIV

Frequency calibration circuit and method thereof

InactiveCN104135285AReduced operating frequency requirementsIncrease the sampling mechanismPulse automatic controlTotal countPhase locked loop circuit
The invention provides a frequency calibration circuit and a method thereof. The frequency calibration circuit comprises a phase lock loop circuit, an M-dividing divider for generating a plurality of phase signals, a sampling circuit for sampling on the rising edges of the phase signals, a first counter for counting reference frequency signals, a second counter counting first phase signals, a logical control circuit for comparing a count value with a target count value to obtain a minimum difference value, and looking up a control bit of a voltage-controlled oscillator through the difference value, and a comparison circuit for judging whether the control voltage of the voltage-controlled oscillator is in a set range or not. The method comprises the following steps: sampling the reference frequency signals to obtain a total count value; comparing the total count value with a target count value; selecting a next resonance line according to a binary lookup flow till binary lookup ends; and outputting a resonance line corresponding to a minimum error in order that the output frequency of the voltage-controlled oscillator reaches a required value. Through adoption of the frequency calibration circuit and the method thereof, the speed and accuracy are increased, and the requirement on the working frequency of a digital circuit is lowered, so that a design method is simplified.
Owner:SHANGHAI JIAO TONG UNIV

Modularized frequency synthesizing method based on direct digital and direct analogue combination

InactiveCN101895292AGood versatility and scalabilityReduce interaction and constraintsPulse automatic controlRadio frequencyIntermediate frequency
The invention provides a modularized frequency synthesizing method based on direct digital and direct analogue combination, including the following steps: (1) direct digital frequency synthesizing method is adopted to generate M intermediate frequency marker signals with frequency interval of deltaF and bandwidth of (M-1)deltaF, namely F1, F1+deltaF, F1+2deltaF, ..., F1+(M-1)deltaF; (2) frequency shifting method is adopted to shift the frequencies of the M intermediate frequency marker signals generated in the step (1) to microwave frequency band, so as to generate M microwave local oscillation signals with frequency interval of deltaF and bandwidth of (M-1)deltaF, namely F2, F2+deltaF, F2+2deltaF, ..., F2+(M-1)deltaF; (3) indirect analogue frequency synthesizing method is adopted to generate N radio frequency marker signals with frequency interval of MdeltaF and bandwidth of (N-1)MdeltaF, namely F3, F3+MdeltaF, F3+2MdeltaF, ..., F3+(N-1)MdeltaF; (4) M microwave local oscillation signals generated in step (2) and N radio frequency marker signals generated in step (3) are subject to mixing, so as to obtain M*N frequency synthesis signals with frequency interval of deltaF and bandwidth of (MN-1)deltaF, namely F2+F3, F2+F3+deltaF, F2+F3+2deltaF, ..., F2+F3+(MN-1)deltaF, and the frequency synthesis signals are output. The invention realizes extremely rapid frequency conversion, extremely low phase noise and extremely low spurious level with low cost.
Owner:中国兵器工业第二〇六研究所

Stable underwater communication node awakening signal detection method

The invention discloses a stable underwater communication node awakening signal detection method. The stable underwater communication node awakening signal detection method comprises the following steps of: S1, emitting a dual-frequency or multi-frequency awakening signal; S2, according to a set initial frequency, transform point number and frequency resolution ratio, executing CZT (chirp z transform) on a unit circle on the awakening signal; S3, searching an extreme value of a zoom spectrum of CZT, judging a signal as the awakening signal if an estimated relative frequency interval and relative amplitude relationship between frequency components are kept unchanged, or judging the signal is not the awakening signal; and S4, after the signal is determined as the awakening signal, powering on an integral communication node to enable the node to be transferred into a working state, and when the node completes working, cutting off a power supply to enable the node to be transferred into a sleeping state. According to the stable underwater communication node awakening signal detection method disclosed by the invention, due to the high frequency resolution ratio, multiple groups of frequencies can be adopted for combination to awaken a plurality of nodes of an underwater sensor network without worrying about mutual interference, so that detection false-alarm is greatly reduced and a service life of the underwater wireless sensor network is prolonged.
Owner:HARBIN ENG UNIV
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