FPGA Implementation Of QAM Modulation And Demodulation In Telemetry Technology

As the increasing amount of telemetry data, the existing modulation can not meet the transmission requirements, So people put forward new requirements on the communication system bandwidth and the transmission rate. Meanwhile, increasingly scarce spectrum resources, how to improve the spectrum efficiency has been the focus of attention. Three basic types of digital modulation amplitude or phase alone to carry information, can not take full advantage of the signal plane, the spectrum in terms of a waste. Need for a new digital modulation techniques for bandwidth resources in conditions of limited access to higher transmission rates. Quadrature amplitude modulation and demodulation technology is an efficient digital modulation, digital modulation techniques than the traditional individual to carry information using amplitude or phase mode, QAM modulation signal amplitude and phase to carry information, can take advantage of the signal plane, thus greatly improving the effectiveness of information transmission, but also has high spectrum efficiency, it has been widely used in QAM digital cable TV transmission and digital MMDS system areas.Firstly, the principle of the 16QAM modem described in detail, discussed in detail, and quadrature amplitude modulation and demodulation techniques in digital frequency synthesis system, FIR digital filter, constellation mapping, synchronization, string and conversion, base conversion, and several other key technology modules. One design for digital frequency synthesis, the paper adopted coordinate rotation digital (CORDIC) algorithm is the cosine of real-time computing is the method, instead of the traditional NCO sine look-up table used to convert the phase margin can be a good use of ROM table to overcome the NCO generated when the phase truncation error, which greatly improved the frequency and phase resolution, and a significant savings in FPGA's internal resources. FPGA technology and then made a brief introduction, by analyzing the proposed FPGA-based 16QAM modulation and demodulation system design and build a model of 16QAM modulation and demodulation system and the environment in the software simulation and analysis of experiments, the final describes the Universal Asynchronous Receiver/Transmitter in the FPGA.This paper presents a FPGA-based digital 16QAM modulation and demodulation scheme that in the Quartus II simulation software development platform, using Verilog HDL hardware description language design and simulation results are given for each module, the last chip in the ALTERA company EP2C8Q208C8 on the functional implementation, experimental results and theoretical analysis is consistent with, and achieve the desired purpose, for the remote telemetry technology to further research and laid a good foundation.