An investigation into mixer in radio communications systems

ABSTRACT

Software radio is one of the hotspots in radio communication and military research. Due to the processing speed of A/D/A conversion and DSP processor, software radio often adopts inter-specific schemes based on digital conversion technology. That is to say, by using specific DDC&DUC or running relevant algorithm, software radio transforms the sampling rate to enable DSP processors bring real-time signal to success. In this dissertation, the mixer and NCO in the DDC are investigated, some typical cases are focused on., then on the basis of result of logic synthesis, the utilization rate of FLE10K's logic resource is analyzed
In the first place, the dissertation presents Current situation and the trend of the modern radio communication and discusses the problem at present, then gives the theory of radio communication and the function, as well as the principle of the mixer. The dissertation emphases mainly on the design of the mixer. The design of the mixer is discussed from two aspects: the design of the NCO, the design of the multiplier. The design of the NCO includes the design of four function module, that is, Phase accumulator module; module producing the harassing code; accumulator module and module for memory altitude of wave. In the course of design, schematics, VHDL, LPM, MAX+ plusII and FLEX10K are all applied, then on the basis of result of logic synthesis, the utilization rate of FLE10K's logic resource is analyzed. When we design the NCO, we adopt the technology of the DDS, as a result, we can control the frequency flexibly. Finally we give some typical cases.

Key Words: software radio; DDC; NCO; DDS; Mixer; FLE10K