Military Ultrashort Wave Radio Digital Research

After the evolution from analog to digital, and from fixed to mobile communication, radio systems are undergoing the third revolution from hard-wired radios to software-defined radios. Software Radio (SR) is one kind of digital signal processing system, which greatly expand the areas of digital signal processing. Considerable research fruits have been achieved in the field, and a few companies in home and abroad have invented the military digital radios.A certain communication company stimulated by market competition and the demand of the current VHF(shorted by "Very High Frequency" ) radios' digital transform, established the "ZX08" project so as to conduct researches on the IF digital and base-band digital signal process. On the basis of others' research achievements, I participated in the R&D work on the digital IF part of the VHF radio. In the thesis, I mainly discuss the digital IF process theory of the SR. Chapter 2 demonstrates the sampling and quantization theory of wideband IF signal ,and multiple rate signal processing theory----including interpolation, decimation and oversampling. Chapter 3 introduces the digital up(down) conversion between baseband-modulated and bandpass modulated signal through orthogonal modulating (demodulating), At last , after discussing FIR filter's properties and design methods, I give a design example.Based on the analog VHF radios transmit/receive principals, chapter 4 illuminates simply the RF module, IF digital module, and audio modules about the "ZX08" project, focused on the hardware design of the digital signal process chip "TMS320VC5410" and introduction of the audio module. Chapter 5 explains the signal flow in the IF module and the theory in FM modulating and demodulating , and shows a few algorithms of the FIR filter design and the spectrum comparing realized by the DSP chip, produces their result in the Matlab simulator and real circuit debugging .For the need of the data transmit, chapter 6 constructs the data transmitscheme of VHF radios, summarizes the whole text, and proposes the improvement and further suggestions for "ZX08" project.In a word, the work which researches the digital VHF radio makes me deeper understand the SR theory , and provides the theory support and practical accumulating for the development of the VHF radio, which can realize better- performance audio and data communication.