The Design Of Weak Signal Acquisition System

Signal detection is the basis to understand the nature, with the deepening of scienceand technology as well as theoretical studies, the limit of signal detection has beendriven to a higher requirement, so weak signal detection is born in this emergingdiscipline. And the rise of weak signals attracts the attention of a large number ofresearch workers.As a part of weak signal detection, the acquisition of weak signal also draws lots otattention, and a lot of research products appear, such as lock-in amplifier, samplingpoints and so on. However, these products have a common characteristic, namelyadvanced equipped and expensive, apply only major research projects. Considering thisshortcoming, this paper analyzes the key technology of weak signal acquisition,intending to build a complete set of weak signal acquisition system for the generalpublic to realize the analog signal processing and digital signal acquisition, so as torecognize weak signal in the PC.Firstly, this paper introduces the knowledge of weak signal detection, describesthe features and status quo at home and abroad, analyzes the applications prospects forlow-cost weak signal acquisition system, which proposes a combination of embeddedand virtual instrument together, and forms a thought of embedded weak signal acquisitionsystem.Then aims at the embedded system, we propose to FPGA and LabVIEW-centricsolutions, refine design, select the right development platform for the gain filter, ADsampling, transmission control and system software to, and gives basis.According to the solution, we analyze, design and develop the components of thesystem. In the hardware part we give several circuits of the gain filtering, AD samplingand control the transmission； according to the hardware and software systemrequirements and system interaction, embedded system completes functions ofcommand interpreter, sampling control and data read and write, while modify the USBfirmware to make the transmission port belong to acquisition equipment exclusively；software system interact data with the equipment and process digital signal, finally thehost computer reproduce and store the sampled signal.At last, we debug the system. By debugging the various hardware and softwaremodules, and the overall system, we realizes the function of weak signal acquisition.