Design And Implementation Of High Precision Data Acquisition And Forwarding Device

The data acquisition and forwarding device is used to collect various types of sensor signals on the aircraft in the flight test,and quantize and forward the data.Because the flight test environment is complex and full of various types of noise,the sensor signal is weak and easy to be covered by noise.How to accurately collect and forward the data is of great significance for the flight test.Combined with the requirements of high-precision data acquisition and forwarding devices,the device is designed with high precision and low noise according to the modularization idea to achieve high-precision acquisition.Firstly,the factors affecting the acquisition accuracy are analyzed.The noise source is analyzed and modeled,and then the design scheme of the high-precision acquisition and forwarding device is proposed.After analyzing the characteristics of the sensor and then focusing on the sensor type,the temperature sensor AD590 is compensated on the hardware to realize the compensation circuit design of the S-type thermocouple.For the high-precision design of the conditioning circuit,the low-noise design is mainly carried out from three aspects: the amplifying circuit,the filtering circuit and the power supply circuit.The amplifying circuit adopts a two-stage amplifying circuit cascading mode composed of a low-noise instrumentation amplifier AD8421 and OPA2277,which reduces the noise introduced by the amplifier and improves the signal-to-noise ratio of the signal input of the conditioning circuit.And the filter circuit mainly adopts RF filtering,second-order low-pass filtering and anti-aliasing filter to filter out interference noise in the signal.For the power supply noise output characteristic,the combination of the switching power supply and the linear power supply is adopted to reduce the influence of the power supply noise on the device,thereby reducing the noise and improving the accuracy of the acquisition.Secondly,in the aspect of logic design,RS422 digital acquisition and sensor analog acquisition are designed for the type of data acquisition.Other than this,aiming at the problem that there are many kinds of analogs,large sampling rates,and difficult frame transmission,the different types of data are designed and transmitted separately.In order to reduce the collected noise and improve the accuracy of the device,an anti-pulse averaging filter design and a FIR low-pass filter design are adopted,and MATLAB is used to verify the filter performance.At the end of the article,the performance of the acquisition and forwarding device is verified from the integrity and accuracy of the data.After verification,the equipment meets the design specifications.