The Design And Implementation Of Ultrawideband Data Acquisition System

The topic of this paper comes from the project of ultra-wideband radar. As part of ultra-wideband radar, the data acquisition should meet the requirements of the signal acquisition, storage and transmission. According to the three aspects, this article will introduce in detail.First of all, the data acquisition circuit of ultra-wideband radar mainly considers about the ultra-wideband signal acquisition. In order to sample the impulse signal with narrow pulse width effectively, the first work needed to design is the sample and hold circuit. The core part of the sample and hold circuit is the design of circuit structure of sampling gate. Through the comparison of various circuit structure of sampling gate, the sample and hold circuit of this project adopts the balance circuit structure with four tube. This circuit structure has high isolation and can effectively eliminate the noise introduced by the sampling pulse, but it is hard to design with this circuit structure. For the balance structure, so it need multiple diode. The diode consistency is very difficult to guarantee. The sampling pulse is generated by step recovery diode(SRD). By the transit characteristics of SRD, which this diode does not immediately stop after the reverse, SRD can generate the sampling pulse with pulse width of hundreds picsecond.Second, after the sample and hold circuit is completed, the data acquisition system need to convert the analog signal to digital signal, storage digital signal and transmit the signal with PC. The signal analog-digital conversion can be realized just by the Analog-Digital Converter. The ultra-wideband radar system adopt the antenna array to transmit and receive the pulse signal, so the data acquisition system need to deal with multichannel signal. To storage the digital signal, this system adopts the First-in-First-out core in FPGA. To transmit the signal, the design uses Ethernet solution. The signal transmission on Ethernet has high transmission speed, long distance and high reliability.Finally, the data acquisition system is experimental tested. This paper shows the result of experimental test and evaluates this result.