TDC Implementation Based on Internal Delay Module of FPGA

2013 ◽  
Vol 816-817 ◽  
pp. 1063-1068
Author(s):  
Rou Gang Zhou ◽  
Yun Fei Zhou ◽  
Guang Dou Liu ◽  
Xiao Tu
Keyword(s):  
Nuclear Physics ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Interpolation Method ◽  
Time Measurement ◽  
Clock Signal ◽  
Signal Delay ◽  
Digital Conversion ◽  
Sampling Points ◽  
Stable Performance

Currently the time to digital converter (TDC) integrated in FPGA performs time-to-digital conversion in the carry chain mode and inter-slot offset is caused to be severe by internal wiring in the FPGA. Based on the carry chain interpolation method, this paper proposes the method for using a delay module in FPGA to achieve accurate signal delay. By calculating the phase difference of multi-clock signal between two latch sampling points, the interval between two sampling points was obtained. Experimental results indicate a measurement accuracy of 78ps or 52ps can be reached by precisely collecting time through the delay module in FPGA. Compared to the carry chain interpolation method, this method is significantly advantageous in small inter-slot offset, stable performance and convenient design and can meet the requirement for time measurement or requirement by laser interferometer with a nm-level accuracy in nuclear physics.

Key technologies analysis and design of ultra-clean & ultra-stable spacecraft for gravitational wave detection

2021 ◽  
pp. 2140021
Author(s):  
Kun Chen ◽  
Xiaofeng Zhang ◽  
Tong Guo ◽  
Zhi-Ming Cai ◽  
Keyword(s):  
Gravitational Wave ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Gravitational Interaction ◽  
Thermal Control ◽  
Theory Of Relativity ◽  
Gravitational Wave Detection ◽  
Analysis And Design ◽  
Wave Detection ◽  
Key Technologies

The observation of gravitational wave enables human to explore the origin, formation and evolution of universe governed by the gravitational interaction and the nature of gravity beyond general theory of relativity. The groundbreaking discovery of Gravitational Wave by Laser Interferometer Gravitational-Wave Observatory provides a brand-new observation way. While detecting gravitational wave on ground is limited by noises and test scale, space detection is an optimized alternative to learn rich sources in range of 0.1 mHz–1 Hz. Considering the great significance of space gravitational wave detection, ESA proposed LISA project, CAS also proposed Taiji project. Due to the extremely weak gravitational wave signal and high measurement accuracy requirement, the spaceborne GW observation antenna is accomplished by three spacecrafts constitute isosceles triangle formation intersatellite interferometer. The arm length of the interferometer reaches millions of kilometers between them, and the measurement accuracy reaches pico-meter magnitude. There are many key technologies including pm magnitude space laser interferometer metrology, drag-free control using TM of Gravity Reference Sensor, [Formula: see text]N micro thruster, ultra-clean & ultra-stable spacecraft, etc. This paper focuses on key technologies of the ultra-clean & ultra-stable spacecraft, analyzing the design of mechanical, thermal control and magnetic clean. Moreover, it reports the preliminary results of the technological breakthrough.

Design of Equivalent Sampling Based on Printed Circuit Board Suited for Power Communication System

2013 ◽  
Vol 333-335 ◽  
pp. 465-471
Author(s):  
Chuan Liu ◽  
Zhi Chao Huang ◽  
Peng Wu ◽  
Lei Chen ◽  
Wei Wang
Keyword(s):  
Time Delay ◽  
Communication System ◽  
High Speed ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Transmission Time ◽  
Clock Signal ◽  
Signal Delay ◽  
Printed Circuit ◽  
Sequential Logic

Many applications in Power communication system have a demand of adjustable transmission time delay of high-speed signal. In sequential logic circuit, the control of transmission time delay of high-speed signal can effectively improve the accuracy of clock sampling, as a result, satisfy the constraints between clock signal and periodic data. A method of equivalent sampling based on printed circuit board (PCB) is provided in the article, it realizes equivalent sampling of the data by fixing a group of clock signal delay, thus, increase the accuracy of sampling.

The Analysis and Design of a Large Stroke with High-Precision Polarized Laser Interferometer System

2016 ◽  
Vol 679 ◽  
pp. 129-134
Author(s):  
Wan Duo Wu ◽  
Qiang Xian Huang ◽  
Chao Qun Wang ◽  
Ting Ting Wu ◽  
Hong Xie
Keyword(s):  
High Precision ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Laser Interferometry ◽  
Phase Shifting ◽  
Single Frequency ◽  
Rejection Method ◽  
The Common ◽  
Frequency Laser ◽  
Polarization Phase

The technique utilizing single-frequency laser interferometry has very high measurement accuracy, but it has rigorous requirements for optical design which is affected by many factors. In order to achieve single-frequency laser interferometry with large stroke and high precision, the integral layout, the polarization phase shifting technique and the common mode rejection method are adopted to design the length interferometry system. This paper analyzes factors and design requirements which affect measurement accuracy with large stroke. Based on polarization phase shifting technique, the system employs the four-beam-signal detection technique and the common mode rejection method, to make a differential processing of four mutually orthogonal signals. Thus, the influences of zero-drift of intensity and environmental change on system are reduced. Combined with a 200 phase subdivision, the system achieves the resolution with 0.8 nm. Under the VC++ environment, the displacement measurement results are compensated and corrected according to the environmental parameters. Compared with the Renishaw XL-80 laser interferometer, the system has better stability in short term. In the measuring range of 60 mm, the effectiveness of the system is verified.

Application of Chirp-z Transform in Doppler Weather Radar

2014 ◽  
Vol 513-517 ◽  
pp. 4265-4268
Author(s):  
Jun Zhu ◽  
Xiao Jia Lu ◽  
Xiang Liu
Keyword(s):  
Signal Processing ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Measurement Accuracy ◽  
Weather Radar ◽  
Doppler Weather Radar ◽  
Transform Method ◽  
Fast Fourier Transform Method ◽  
Sampling Points ◽  
Signal Processing Methods

Among the signal processing methods of Doppler weather radar, the FFT (Fast Fourier Transform) method is widely used. If the measurement accuracy needs to be improved, the number of FFT points also needs to be increased. As a result, the amount of computation increases exponentially. Chirp-z transform can directly refine certain spectrum in the spectrum of weather echoes. In the case that the sampling points and the amount of computation increase fewer, the measurement accuracy can be greatly advanced.

Precise Time Measurement Using CTMU

2012 ◽  
Vol 214 ◽  
pp. 232-236
Author(s):  
Xiao Qiong Zuo ◽  
Ya Xian Liu
Keyword(s):  
Measurement Accuracy ◽  
Low Cost ◽  
Time Measurement ◽  
Analog To Digital Converters ◽  
Analog To Digital ◽  
Current Consumption ◽  
Measurement Resolution ◽  
Precise Time

Numerous applications require very precise time measurement. Usually, the measurement accuracy is increased by improve the MCU MIPS. It will take the high cost and current consumption, and the accuracy is limited in the MCU MIPS. Using CTMU channels work in conjunction with Analog to Digital converters, the high precise time measurement with low cost MCU can be achieved, and make the time measurement resolution to 1 nanosecond. CTMU module is available in many Microchip microcontrollers.

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