ECE 4634 Digital Communications | ECE | Virginia Tech

Undergraduate PROGRAMS

Course Information


System and signal level analysis and design for digital communications systems. Review of analog-to-digital conversion and digital baseband communications. Detailed analysis of digital carrier modulation formats including assessment of signal-to-noise ratio, bit error rate, and power and bandwidth efficiency for amplitude-shift keying (ASK), phase-shift keying (PSK), frequency-shift keying (FSK), and Quadrature-Amplitude Modulation (QAM). Matched filter receivers and receiver design, link budgets, and multiple access. Additive-white-noise Gaussian channels. A detailed discussion of random variables will be included to supplement prerequisite material.

Why take this course?

The course introduces students to the fundamentals of system level design and analysis of digital communications systems. This material is necessary for advanced study of digital communications systems, and the skills acquired in this course are fundamental for employment in the rapidly growing communications industry.

Learning Objectives

  • 1. Design digital communication systems (e.g., choose modulation scheme, coherent vs. non-coherent), given constraints on data rate, bandwidth, power, and bit error rate;
  • 2. Analyze the performance of a digital communication link when additive noise is present in terms of the signal-to-noise ratio and bit-error-rate.
  • 3. Compute the power and bandwidth requirements of modern communication systems, including those employing Amplitude-Shift Keying (ASK), Phase-Shift Keying (PSK), Frequency-Shift Keying (FSK), and Quadrature-Amplitude Modulation (QAM) modulation formats;
  • 4. Determine the auto-correlation function of a line code and determine its power spectral density (PSD);
  • 5. Determine the power spectral density of bandpass digital modulation formats.

Course Topics


Percentage of Course

1. Basic signal and noise theory, modulation, spectra 5%
2. Digital communications:
Digital baseband signaling (autocorrelation and PSD of line codes) 5%
Analog-to-digital conversion 5%
Digital bandpass modulation (including ASK, PSK, FSK, and QAM) 20%
Signal space representation 10%
3. Effect of noise on Communication systems:
Probability theory & random variables 5%
Properties and representation of noise (including AWGN) 5%
Matched filter receivers 5%
Optimum detection and detection performance 5%
Signal to noise ratio 5%
Bit-error-rate in digital links 10%
Bandwidth and power requirements 5%
Introduction to error correction coding 5%
Symbol/frequency acquisition and tracking 5%
Wireless communication systems (link budgets, medium access) 5%