Based On The Pxi Bus Qpsk Modulator Design

Military testing radio stations scene interference is severe, need to process large volume of data, probably need to support multiple standards, and the software should be able to change its operation mode, performance parameters flexibly, to meet wartime requirement. Furthermore, it must be convenient and quick to replace equipment whether because of the equipment breaking down or the special need at wartime. Based on above factors, at the beginning of the design, data throughput, strong anti-jamming capability, stability and reliability, integration, and requirement of convenient equipment replacement must be considered.Therefore, we designed QPSK modulation test platform based on PXI bus.The peak data transmission rate of PXI is up to 132MB/s and 528MB/s when at 33MHz, 32bit and 66MHz, 64bit respectively. Each expansion slot on PXI backplane has dedicated 10 MHz reference clock. Clock deviation is less than 1ns, and could serve as a clock basis to achieve synchronization. PXI also support hot plug, facilitating rapid replacement of equipment. In addition, the PXI strictly abide by the IEC-1076 machinery specification, anti-oscillation, Stability and anti-interference performance is very good. QPSK modulating mode has good anti-interference performance, whose carrier can carry 2bit binary information transmission and coding rate, 2bit/Hz bandwidth utilization, and flexible developing method, making this be a good test platform to meet the needs of field wartime environment.This paper gives system hardware platform based on digital signal processor with 3U card structure, PXI 33 MHz system clock. 32bit data width. The corresponding software development was implemented in several mature, reliable integrated development environments currently, such as TI's CCS was used to develop DSP related program, Xilinx's ISE and Mentor Graphics'Modelsim were used to develop CPLD related program, and VC6.0 combined with WinDriver were used to develop PXI kernel driver.After the actual test, analog RF signal transmission rate being up to 6Mbps, the carrier frequency being up to 42MHz, and bandwidth threshold being 55MHz were successfully achieved. Of course, if the main clock of modulation module is up to 160MHz, the maximum bit rate will be up to 20Mbps, corresponding carrier peak up to 65MHz.The system has high reliability, integration, and makes full use of a programmable DSP advantages to make the system as a whole have certain flexibility. And the use of CPLD online programming characteristics makes system debug convenient.The test system has following advantages compared with traditional radio test station: automatically starting with power on, testing automatically, and small size. Morever, modular design solution provides a new idea for future military radio test system design.