University of Electronic Science and Technology of China

Duyu Qiu

Hao Zeng

Lianping Guo

Peng Ye

Jun Jiang

Qinchuan Zhang

Kuojun Yang

Feng Tan

Huiqing Pan

Wuhuang Huang

Shulin Tian

Yu Li

Houjun Wang

Yong Zhao

Shuhao Wu

Chuanyun Xiang

Xianggong Guo

Xingqi Liu

The present invention provides a method for equivalent high sampling rate FIR filtering based on FPGA, first, the coefficients h(k) of FIR filter are found by using MATLAB, multiplied by an integer and then rounded for the purpose that the rounded coefficients h(k) can be directly used into a FPGA, then the ADC's output of high data rate fs is lowered by dividing the ADC's output x(n) into M parallel data streams xi(n) of low data rate, and the M&#xd7;L samples in one clock cycle is obtained by delaying the M parallel data streams xi(n) simultaneously by 1, 2, . . . , L' periods of the synchronous clock, at last, the samples yi(n) of FIR filtering output is calculated according to the samples selected from the M&#xd7;L samples, and the filtered data y(n) of data rate fs is obtained by putting the samples yi(n) together in ascending order of i. Thus, the continuous FIR filtering of an ADC's output sampled with high sampling rate is realized, while the data rates before and after the FIR filtering are unchanged.

Method for equivalent high sampling rate FIR filtering based on FPGA

A method for oscilloscope 3D mapping in scan mode. The input signal is acquired using a real-time sampling rate which is Dtimes higher, thus more sampling points, i.e. Dacquired data can be obtained during the time interval between two consecutive horizontal pixels. The Dacquired data are mapped into a same column of the screen to implement fluorescent waveform display. In addition, to realize the scanning display, a flag X is introduced into the three-dimensional database, when the screen refresh signal arrives, the first Dacquired data are read out from the unread acquired data in FIFO memory. The three-dimensional database is updated from the flag X, which make the leftmost waveform always be the oldest waveform, the rightmost waveform always be the newest waveform. Thus the 3D mapping is realized in scan mode, letting the DSO have a fluorescent waveform display at slow time-base.

Method for oscilloscope 3D mapping in scan mode

The present invention provides a temperature-compensated crystal oscillator based on digital circuit, a closed-loop compensation architecture is employed to realize the high precision compensation of the crystal oscillator. The output frequency f(T) of the TCXO to be compensated is directly connected with the compensation voltage Vc(T) in real time, and the compensation voltage is fed back to the voltage control terminal of the VCXO to be compensated to compensate, so that the output frequency after compensation is equal to the target frequency signal, thus avoiding the frequency shift of output signal caused by temperature hysteresis, i.e. the discrepancy between the temperature acquired by a temperature sensor and the real temperature of the resonant wafer in the prior art.

Temperature-compensated crystal oscillator based on digital circuit

The present invention provides a method for a method for measuring the properties of liquid based on a quartz crystal microbalance sensor, which employs two measurements to obtain two frequency shifts of the QCM sensor induced by two different volume of the sample liquid. The present invention creatively established the relationship between the density and viscosity of sample liquid and the frequency shifts of QCM sensor. With present invention, the density and viscosity of sample liquid can be obtained through two frequency shifts. Comparing to the conventional liquid property measurement. The measuring procedure of present invention are more simple, and the measuring results are more accurate. Moreover, the present invention consumes less volume of sample liquid, and has the features such as online, real time and quantitative.

Method for measuring the properties of liquid based on a quartz crystal microbalance sensor

For the signal under acquisition which varies monotonically before and after the trigger time, a method for full-digital random sampling employs first sampled data before the trigger time and first sampled data after the trigger time to fit a curve, and obtains an intersection point of triggering level and the fitted curve, then, calculates the time interval between sampled data after the trigger time and the intersection point in the end, reconstructs the original signal, i.e. the signal under acquisition by a time interval of each acquisition. Thus, an analog trigger circuit and a time measurement circuit of conventional random sampling system can be eliminated, that simplifies the circuit design of data acquisition system and decreases its hardware complexity. Moreover, the higher sampling rate for the signal under acquisition is attained, and more waveform details are obtained.

Method for full-digital random sampling

A method for adjusting the waveform brightness for a waveform formatted to be displayed on a digital three-dimensional (3D) oscilloscope having M brightness gradation levels to display the waveform on a digital 3D oscilloscope having L brightness gradation levels is includes, creating a ROM in an FPGA and storing a look-up table of screen display brightness value of LCD that is corresponding to the waveform occurrence N(T,A) at the current brightness gradation L. The ROM is divided into 2sub ROMs, each sub ROM has the capacity of 2&#xd7;d bits. A value of round(p&#xb7;N(T,A) is assigned to waveform brightness value D(T,A) and is stored correspondingly into the subROMof 2&#xd7;d bits by ascending order of the b bits of binary data of waveform occurrence N(T,A). In this way, using the b bits of binary data of waveform occurrence N(T,A) as the binary address of the subROM, corresponding waveform brightness value D(T,A) at the current brightness gradation L can be obtained through look-up table in the subROM.

Method for quickly adjusting the waveform brightness of digital three-dimensional oscilloscope

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Chengdu, China

Duyu Qiu