The Design And Implementation Of Embedded Communication Signal Generator

Communication signal generator is a commonly used instrument for the design of the communication system, the domestic use of high-end communication signal generator mainly rely on imports, which is expensive and inconvenient to upgrade. It is not easy for secondary development. With the rapid development of communication technology, various new baseband and modulation technologies continue to emerge. Communication signal generator must constantly upgrade also. So, the development of a communication signal generator, which is low cost, easy to upgrade and secondary develop, has important application value.This paper describes the design and implementation of an embedded communication signal generator. The structure of the signal generator is ARM + FPGA, giving full play to the advantages of ARM processor in the application development and the advantages of FPGA in the signal analysis processing flexibility. The signal generator is capable of flexibility to produce a variety of commonly used communication signals. The main contents of this paper include:(1)The design of the hardware system: hardware circuit including the embedded system hardware circuit, FPGA and its peripheral circuit, the interface circuit between FPGA and ARM, baseband signal generation circuit, modulation signal generating circuit(WBX RF board) and power supply system. The embedded processor is chosen as S3C2440 A embedded ARM9 processor of SAMSUNG Corp with high performance. Using touch screen and mouse as input device, system set/display the signal parameters and the waveform through the Qt graphical user interface program on the touch screen. Xilinx XC3S1600 E FPGA is responsible for signal processing, control DAC AD9799 A and WBX RF board to generate the baseband signal and the modulation signal. In addition, in order to improve the driving ability of the baseband signal, the system uses high-speed op amp AD8021 for baseband signal amplification.(2) The design of software system: system software including embedded Linux system software design and software design of FPGA system. ARM system run the embedded Linux operating system. Its software design includes embedded Linux system(including u-boot, Linux kernel and root file system) transplantation, dual port RAM, touch screen and an external device driver program design, QT graphical user interface application program design. FPGA system is using for baseband signal processing. It receives the signal parameters from ARM, processes them to generate waveform data. Finally FPGA control peripherals and generates the baseband signal and the modulated signal.(3) System hardware production and debugging together with software: system design with four layer PCB circuit board. After the welding components and circuit debugging, system hardware production is completed. Then the software debug based on the system hardware, realize the function of the system.(4) Test results: test results show that the communication signal generator designed in this paper can generate the baseband signal and the modulation signal according to user settings. The design achieves the desired function and requirements.