Design Of A High-speed Array Signal Data Acquisition System Based On PXI Architecture

In radio astronomical observations, signal spectrum ranges from several MHz to thousands of GHz. With the observing frequencies higher and higher, and the more complex electromagnetic environment, radio astronomical observations sets higher requirements on the terminal recording equipments at the weak signal reception, position determination of celestial objects and frequency resolution. Array signal processing has advantages in signal enhancement, interference and noise reduction, source positioning, etc. It plays an important role in radio astronomical observations.The software-defined radio architecture is used in this paper. With the requirements of high sampling rates and precise source positioning, the high-speed array signal data acquisition system based on PXI structure is designed in this paper using the NI FlexRIO modular instruments and the Lab VIEW graphical programming technology. The system has two operation mode:high sampling rate mode and DOA estimation mode. It is mainly composed of the slave computer(modular instrument) and the master computer(PC). The structure of the slave computer is PXI-based FlexRIO, including a high-speed ADC adapter module, an FPGA module and a PXIe chassis. The time interleaved sampling algorithm embedded in the FPGA module doubles the sampling rate through configuring the ADC module. At the same time, the congestion problem existing in the uploading through the PXI bus is optimized. The personal computer stores the received data and analyzes its power spectrum to obtain some useful information.In the DOA estimation mode, the slave computer can utilize the dual channels to generate the sampling data directly under the strong noise, and the master computer can estimate the DOA through the received data.Experimental results and engineering tests show that the system can achieve high-speed sampling 3.0GS/s and upload the data to PC stably and rapidly. The system can make more accurate DOA estimation under the strong noise.