BE201 Digital Communication Assignment 2 Group Project: Written assignment Topic: Matlab coding, signal transmission, sampling, filtering and Fourier analysis Submission Due: Week 11 (11pm on 5th June 2016) Total Marks = 100 (10% of total assessment) Word Limit: 2000 Words (12-point font in Times New Roman) Note: Students should work in teams of 3-4 students each. Every student should find a team mate. Students are encouraged to work with even people they are not accustomed to. Purpose of the assessment: The purpose of this assignment is to motivate students to learn MATLAB programming and how to use software to solve problems numerically. In summary, the learning outcomes in this project include: a. Simulate digital communication applications using Matlab. b. Explain the need for sampling. c. Apply the principles used in the generation, transmission and reception of signals. a. Demonstrate analytical and problem solving skills. b. Demonstrate the ability to work efficiently and effectively in team environment. c. Prove the ability to apply content learned during their studies to solve problems. d. Develop research and lifelong learning skills. e. Develop the skill to write professionally-looking technical reports. Description of the assessment: 1. Background The main purpose in digital communications is the generation, processing, storage and transmission of signals. The transmission medium is non-ideal and thus processes the signals passing through it in its own manner. In essence, a transmission medium works as signal filter. One of the important things is the knowledge about how the signals are changed by the channel. Fourier analysis is used to decompose signals into their frequency components. By so doing we are able to analyse the signal and the potential effects of the transmission medium on them. Many things in digital communication systems cannot be handled manually. Thus, there are several software packages available for the design and analysis of digital communication systems. One of the most popular ones supported by the industry is MATLAB. Thus, it is beneficial for students to know how to use it proficiently. Questions Consider the signal xt e4tut where u(t) is the unit step function. (a) Manually compute the Fourier transform of the signal x(t). (b) Derive the 3-dB or half-power bandwidth (WdB) of this signal? Assume that the signal x(t) has been transferred over an ideal low-pass communication channel with the impulse response h(t) and transfer function H(f) which has the cut-off BE201 Assignment 2 Page 2 of 3 frequency of f cutoff  32 W3dB as illustrated below. The signal that reaches the receiver is y(t). (c) Describe y(t) by comparing and contrasting it with x(t). What are the effects of the transmission system on the information-bearing signal x(t)? (d) Use MATLAB and the discrete Fourier transform (DFT) to numerically compute the Fourier transform of y(t). [Note that the FFT is usually used to compute the DFT to reduce processing.] Explain how you proceed with your work. In particular, explain how you chose:  The sampling period Ts  The sampling frequency fs  The number of samples of y(t), N0, used.  The spectral sampling interval (i.e. sampling interval of Y(f))  The law or theorem governing sampling of a signal (e) Graph X(f) and Y(f) over the frequency range 0  f  300Hz and compare them. We use the functions "plot" for continuous and "stem" for discrete graphs in MATLAB. 2. Requirements The requirements are found in the marking scheme table below. Suggested approach: 1. Students are required to analyse the questions given individually and with their team members in order to thoroughly understand the subject matter and solve the questions. 2. The student must research and learn anything unknown that is required to complete the assignment. 3. Each team is required to submit a concise technical report while being mindful of word limit. Submission Guidelines: Your assignment should be completed according to the General Guidelines for Presentation of Academic Work. 1. successful completion of required tasks 2. quality of figures (no copy-and-paste graphics allowed!) a. comments b. meaningful names 3. accompanying documentation including a. table of contents and page numbers b. a front page - indicating your names. c. list of references used (IEEE referencing style) as an evidence of research depth. x(t) y(t) BE201 Assignment 2 Page 3 of 3 4. The assignment must be submitted in soft (electronic) as .doc file on Moodle page provided at MIT intranet. The page numbers of the assignment must be clear on each page. Marking criteria/rubric: Marks are allocated as follows: Section to be included in the report Description of the section Marks Analytical and logical reasoning Demonstration of the correct application of analytical reasoning and representation. 15 Scope A high level description as introduction demonstrating the understanding of the case study. 5 Signal transmission and filtering Demonstration of thorough understanding of the filtering effects on signals of communication channels. 10 Sampling theorem and its applications Demonstration of thorough understanding of the sampling theorem and its applications in digital communications. 10 Fourier analysis Differences between Fourier transform, discrete-time Fourier transform (DFT) and fast Fourier transform (FFT). 10 Research depth Literature review of digital filtering and Fourier theory and their importance in digital communications. 10 Hands-on work/MATLAB Correct MATLAB code with figures as outputs of code illustrating understanding of the s/w package. 10 Recent developments What new techniques are available for signal analysis and how they claim to outperform DFT/FFT. 10 Reference style IEEE 10 Individual contributions The report clearly states the contributions of every team member, and lists names and student IDs of all team members. 10 Poor writing Inadequate structure, careless presentation, typos, or the report exceeds the word limit by more or less than 10% -30 Plagiarism Type of plagiarism - Copy from other student - Copy from internet source/textbook - Copy from other sources -100 Total 100 Extensions: Requests for an extension, accompanied by supporting documentation, must be received by the student in writing before 3 working days from the due date else penalties may apply for late submission without an approved extension. Special consideration form is available on level 8 reception. Penalties: Academic misconduct such as cheating and plagiarism may incur penalties ranging from a reduced result to program exclusion.