The Design For Analog Channel Of Data Acquisition And The Research For Relevant Problem

On the boundary of DAC, integrated data acquisition (DAQ) system is devided to analog channel and digital part. Analog channel regulates signal to be acquired to range of DAC in order to improve precision of system. Compared to digital part, analog channel is more sensitive to noise, so improving anti-interference of analog channel will improve SNR of system. This thesis has designed high-speed analog channel for high-speed DAQ system based on VXI bus, and programable control analog channel based on ARM7 for rocket engine dynamic parameter measure system, and done anti-interference design with EMC. High-speed analog channel is required basic gain-flattened in 50MHz signal bandwidth. In main circuit, attenuation circuit composed of resistance-capacitance divider voltage net and amplifying circuits composed of an ultralow noise and distortionvoltage feedback op amplifier AD8099 are designed. Gain flatness has been improved. According to oscillograph probe improving frequency characteristic, hollowing ground layer decreasing crosstalk, and high speed PCB design, basic scheme has been developed.Programable control analog channel based on ARM7 solves high precision and gain independent control problems. Embedded controller LPC2138 is applied as core controller. Programable control module, zero auto-calibration module, gain auto-calibration module, filter module, and man-machine interface module have been designed. Hardware-circuit design, transplantingμC/OS-II operating system and compiling control program have been completed in this thesis.For electromagnetic interference of hardwear and softwear in design and experiments of analog channels, according to EMC theory and EMC emulation technology, grounding anti-interference, power EMI filter and software anti-interference have been proposed, and have been verified in experiments.The tested results indicated that two analog channels have both met the design requirement with good capability and perfect function. They have been applied in both DAQ systems.