Electronic Information Engineering Graduation Design Opening Report

This subject comes from the construction of the laboratory, and the research object is the matlab simulation of signal modulation and demodulation.

2. The purpose and significance of the research

2.1, purpose

I chose the "matlab simulation of modulation and demodulation of signals" as the graduation project. Its main purpose is to further study and consolidate the communication principle and related knowledge through this course design, and learn to use the knowledge learned, in design. In the process, we can comprehensively apply the knowledge content, further familiarize and master the use of matlab; have a deep understanding of the principle of signal modulation and demodulation and its implementation; lay a solid foundation for entering the society to participate in the work; The ability to digest data and comprehensive data, etc.

2.2, meaning

Engaged in the electronic communication industry and can not be skilled in the use of matlab electronic circuit design software, it will be difficult to work and study. In the fields of mathematics, electronics, finance, etc., the use of computer software such as matlab to design and simulate products has become a trend long ago. The advent of such software has greatly improved the design of designers in the communications, electronics and other industries. Product design quality and efficiency. It is well known that in the actual process, the signal transmission is subjected to modulation and demodulation. Since the original signal transmitted by the message, that is, the modulated signal has a spectral component with a lower spectrum, such a signal is not suitable for transmission in many channels. Thus, a modulation process is usually required at the transmitting end of the communication system, whereas a demodulation process is required at the receiving end.

3. Research status and development trends at home and abroad

3.1, research status

Matlab is a science and engineering computing software launched by math works company in 1984. Through matlab and related toolboxes, engineers, researchers, mathematicians and educators can complete the corresponding scientific calculation work under a unified platform. .

Matlab itself contains more than 600 functions for mathematical calculations, statistics, and engineering, so that scientific computing tasks can be completed quickly without additional development. The industry-leading toolbox algorithm greatly expands the field of matlab application, so matlab has received extensive attention since its introduction. The signal processing toolbox is one of them. In the signal processing toolbox, matlab provides filter analysis and filtering. Function implementation, ferr filter implementation, iir digital filter design, iir digital filter order estimation and other functional commands.

3.2, development trend

As the engineering problems we face become more and more complex, the technology that relied on the analysis in the past has become less and less useful. Using computers to analyze and solve engineering problems is a necessary tool for today's engineers. Using matlab software for scientific computing can greatly speed up the research and development of researchers, reduce the time and limited expenditures in writing programs and developing algorithms, and achieve maximum performance.

4. The main content of the research and the application value of the design results

4.1, the main content of the study

1, the principle of signal modulation and demodulation

It is well known that in the actual process, the signal transmission is subjected to modulation and demodulation. Since the original signal transmitted by the message, that is, the modulated signal has a spectral component with a lower spectrum, such a signal is not suitable for transmission in many channels. Thus, a modulation process is usually required at the transmitting end of the communication system, whereas a demodulation process is required at the receiving end. However, the simulation and implementation in the computer are all digital. If the sampling frequency is higher, the distortion caused by the digital is not easy to detect. It is very convenient to use the computer to process the signal. This is one of the reasons why numbers replace analog.

2. The basic way of signal modulation and demodulation

A high frequency sinusoidal signal is often used as a carrier signal in signal modulation. A sinusoidal signal has three parameters of amplitude, frequency and phase. These three parameters can be modulated, which are called amplitude modulation, frequency modulation and phase modulation. It is also possible to use a pulse signal as a carrier signal. Different characteristic parameters of the pulse signal can be modulated. The most common is to modulate the width of the pulse, called pulse width adjustment. There are three basic ways of digital signal modulation, including amplitude keying, frequency keying, and phase keying.

The process of detecting the modulated signal in the first modulated signal in the demodulation of the signal is called demodulation or detection. Amplitude modulation is to change the amplitude of the modulated signal with the value of the modulated signal, so the envelope shape of the amplitude modulated signal is consistent with the modulated signal. Demodulation can be achieved as long as the envelope of the amplitude modulation signal can be detected. This method is called envelope detection. After the detected signal, low-pass filtering is performed to filter out the high-frequency signal, and the desired modulated signal can be obtained to realize demodulation.

3, signal modulation and demodulation matlab teaching program

With matlab itself containing more than 600 functions for mathematical calculations, statistics, and engineering, you can quickly complete scientific computing tasks without additional development, and signals and systems, communication system toolkits can be easily used with matlab Development Language - The m language quickly simulates the process of signal modulation and demodulation.

4, the entire system implementation process

First, use Matlab to compile the textbook file, call the corresponding function on the signal to perform various modulations, generate various types of modulated waves and demodulate them, and perform spectrum analysis at the same time, then demodulate and simulate them by using the simulink toolbox, and change the parameters. And the observation results provide a good basis for the design and improvement of the system.

4.2, the application value of matlab simulation of signal modulation and demodulation

Modulation and demodulation is one of the important issues in signal processing, and the simulation and design of the system are important steps and necessary guarantees in the design process. Using matlab, it is very convenient to analyze and simulate the communication system, especially for the teaching and design of our electronic information major. On the other hand, it can also provide simulation for the courses such as "High Frequency Electronic Foundation" and "Signal and System". Computer virtual test of modulation and demodulation of signals.

5. The main stage and progress of the work

Before the 11th week of the fall semester of XX

Accept the graduation design task book and learn the graduation design requirements and related regulations.

, the 12th to 20th week of the fall semester of XX

Read the specified reference materials and documents, and basically complete the tasks such as opening the report and foreign language translation.

, the first week of the spring semester of XX

Further revision and improvement of the opening report and foreign language translation, so that it meets the requirements of graduation design specifications in terms of content and format.

XX, the second semester to the sixth week of the spring semester

Complete the unit circuit design, protel auxiliary analysis.

Week 6 to Week 12

Complete circuit production and debugging.

Week 13

Complete the graduation design and submit all the results to the instructor for review.

Week 14

Graduation reply

6, the final goal and completion time

Complete the hardware design, provide the protel circuit schematic and pcb printed layout, and finally achieve the goal of the hardware software can be applied accurately.

Completion time: week 15

7. Existing conditions

Existing protel software and necessary equipment for making hardware can complete the research and design of this topic.

references

1. Xie Zimei and other electronic circuit design, experiment, test. Wuhan: Huazhong University of Science and Technology Press. July XX. Second edition

2. National College Student Electronic Design Competition Organizing Committee. Selected works of the 5th National Undergraduate Electronic Design Competition Awards XX. Beijing: Beijing Institute of Technology Press. January XX. Edition

3. Sun Jiping 900mhz dds|pll Applied Coal Science and Technology in Mine Wireless Communication System XX Year 10

4. Zhang Suwen and other high-frequency electronic circuits. Beijing: Higher Education Press. April 1993. Third edition

5. Wang Zhengmou protel circuit design practical tutorial. Beijing: Publishing House of Electronics Industry. June XX. Edition

6. Guo Yong and other protel 99 se printed circuit board design tutorial. Beijing: Mechanical Industry Press. June XX. Edition

7. Xu Zitu electronic circuit simulation platform and tutorial. Wuhan: Huazhong University of Science and Technology Press. January XX. Edition

8. National College Student Electronic Design Competition Organizing Committee. The winners of the 5th National Undergraduate Electronic Design Competition were selected 94-99. Beijing: Beijing Institute of Technology Press. January XX. Edition

9. Zeng Xingwen and other high-frequency electronic circuits. Beijing: Higher Education Press. January XX. Edition

10. Xiao Lingni and other protel 99 se printed circuit board design tutorial. Beijing: Tsinghua University Press. August XX. Edition

11. Liu Qingquan, Ren Bo, Liu Yusheng, Research on Variable-Phase Phase-Locked Loop in Frequency Hopping Communication. Journal of Shenyang Ligong University XX, No.02

12. Peng Yu et al. A digital programmable oscillator for fsk modulators. Sichuan Institute of Technology, XX, 01

13. Development of Wang Zhongya Bujiawu Phase-locked Loop FM Transmitter Journal of Hubei University of Technology XX Year 01

14. Tang Wangang et al. Using the Matlab Communication Toolbox for Frequency Synthesizer System Analysis and Simulation China Test Technology XX Year 01

15. Wang Yantian Dan Dan Cao's design based on fpga's small power stereo transmitter. Journal of Nanhua University XX, 01