The Research Of Software Defined Radio RF Front-end

Software radio is a solution to the problem that multi-system co-exist in the field of radio communication, and there is no standards within those systems. Based on a hardware platform, software radio can achieve a variety of communication functions by the means of software programming. The transceiver RF front-end is the main components of the hardware system, and the capacity of transmitting signal is directly related to the quality of the communication signal. At present, the RF front-end transceiver tend to improve its overall performance such as a standard structure, multifunction, excellent indexes.From theoretical and technical angles, this paper studied the internal structure of both the receiver and transmitter, compared their advantages and disadvantages, and eventually established the design scheme of the RF front-end transceiver. Combining the indicators analysis and design scheme, this paper conducted a detailed distribution of the indicators of the receiver and transmitter, and designed normative structure-based RF board based on6U board. In terms of the structure, the RF board possess not only receiver and transmitter, but also digital circuitry and the interface for the configuration parameters. We can input various configuration commands to the digital part of the FPGA through interface, and then the digital circuit send control information to the RF board. On the RF board, the interfaces to transmit configuration parameters are in a variety of forms, we can choose a suitable one according to the actual need.From the aspect of the performance, both of the receiver and transmitter on the RF board achieve high indicators, with its frequency resolution as low as0.001Hz and the local oscillator phase noise better than-95dBc/Hz@10kHz. When in normal communication, the spurious are less than-47dBc, the fluctuate range is less than1.5dB. While in emergency communications, the bandwidth is up to100MHz, the spurious are less than-40dBc, and the fluctuate range is less than4dB. Besides, the clock on the RF board can be either supplied by the interior or input from the external. There are two ways of LO frequency configuration, namely by internal interface and external interface. The overall configuration parameters have three interfaces both inside and outside. Finally, according to the test results of the RF board, we proposed to improve it by the means of increasing indicators, expanding the band and function, so as to perfect its performance.