Fpga-based Digital Fm Transmitter Technology Research

Telemetry is an effective way to measure the distant between two away from objects .During the trial period of missile research, all the data is transmitted to receiver and demodulated for the researchers. As the rapid development of strategic and tactical weapons as well as space shuttle, the requirement to the telemetry is remarkable increased. Telemetry is an important part of the aeronautics and astronauts system.Telemetry consists of transmitter, antenna and receiver. Traditional analog modulated transmitter is mature which modulates the frequency of VCO by making use of the changeability of diode's capacitance. The property of diode limits code rate as well as frequency-offset. With the developing of High-speed chips and Software Radio, Digital Modulated Transmitter has gradually broken through the limitation of traditional analog transmitter, with the advantages of adjustable and programmable center-frequency , recombinable mode of modulation etc, the digital transmitter will become the mainstream in the future. This paper discusses how to use Field Programmable Gate Array and Max+plusâ…¡ as well as VHDL to design the digital transmitter of DDS+PLL+SSB mode in Telemetry.There are four parts about the digital transmitter design: scheme selection, system design, hardware design and VHDL design.Firstly the paper analyzed the disadvantage of analog transmitter as well as the advantage of the digital transmitter and pick up the design scheme. Then the EDA tool and the way to design circuit are introduced in chapter 2; all the parts of digital transmitter which include A/D,DDS,PLL,SSB and D/A are introduces in chapter 3; in chapter 4, we discuss how to realize the design by hardware and VHDL, meanwhile the test results of the design are given; Finally a conclusion is made: the design is a feasible and effective way and discuss the questions which need to be researched more in the future.