Research On Synchronous Measurement Technology Of Multi-channel Pulse Signals Based On FPGA

Synchronous measurement technology of multi-channel random pulse signalsis very important for industry and aerospace field. For a long time, the multi-channel synchronous measurement of random pulse signals is faced with someproblems, such as only few measuring channels, hard Synchronicity and poorapplicability. To solve these problems, the paper proposed a design to solve theproblems based on FPGA, including the design of multi-channel pulse signal source,waveform recording module and PC software. The waveform recording module hasthe feature of large number of input and output I/O ports, programmable design,flexible design, strong stability and so on. What’t more, this design approach couldachieve the synchronous measurement of multi-channel pulse signals, and it has nodelay measurement problem.Waveform recording module can simultaneously measure32channel randompulse signals’ edge of the time and pulse width, and can easily achieve moreparallel extension of channels. It will begin timing in case of the first signal jump,and then start32-channel signal measurement system at the same time, recordingevery pulse signal jump alone with the arrival of the edge moment, thecorresponding channel number and the low or high status of the voltage. Waveformrecording module contains signal processing circuit and FPGA signal acquisitionand processing module. Signal processing ciicuit is mainly used in the cosmetic andoptical coupling isolation. The FPGA signal acquisition and processing modulehave the functions of anti-jamming filtering, edge detecting, waveform recording,FIFO storing and asynchronus serial transmiting. Anti-jamming filter uses themethod of the finite state machine, which can sffectively filter all kinds ofinterference in the measurement environment, such as the high-frequencyinterference of string into the system and the jitter caused by internal equipmentrelays’ and switches’ action. Edge detection module is able to identify the changesof the edge. The waveform recording module is used to record waveforminformation and frame. The data should be stored into the FIFO first, and thentransmitted through the serial bus to the PC.The paper has designed a systematic operating software of PC, which is usedto cooperate to work with PC. The Program is based on LabVIEW. It has thefunctions of filtering time onlion, frame, display, storage and so on.In order to verify the correctness of the design scheme, paper used freescalmicrocontroller MC9S12XDP512as multi-channel pulse signal source to simulate the conditions of sending synchronous pulse signals in inference and withoutinterference.After experimental verification,32channel random pulse signal waveformrecording module could realize the synchronus measurement and anti-jammingfiltering function. The largest amount of acquired data was less than160frames persecond. That is to say, each channel edge can’t change more than5times per secondon average. Under the condition of less than30minutes in measurement, themaximum error was less than20ms. On this basis, making up for measuring errorthrough the linear least squares fitting method. The experimental results showedthat the accuracy of measurement has been improved further.