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EE350: Communication Systems

Explore the fundamentals of modulation (AM, FM, PAM) and demodulation in communication systems, along with noise concepts and terminology. Learn about channel challenges, additive noise, non-linear distortion, frequency response, and more. Gain insights into the transmission of analog signals, carrier waves, modems, and error detection and correction techniques. Dive into advanced topics such as multiplexing, sampling, and frequency division. Stay updated with course materials and schedules on DoctorD's website. Enhance your understanding of communication systems with real-world applications and practical implementations.

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EE350: Communication Systems

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  1. EE350: Communication Systems Modulation (AM, FM, PAM), Demodulation and NoiseFairfield University:School of Engineering DoctorD: Jeffrey N. Denenbergjeffrey.denenberg@ieee.orghttp://doctord.webhop.net EE350

  2. The Communication Problem • Get information from here to there • Channel challenges • Additive noise: “white”, Gaussian noise here • Non-linear distortion and time variation: only touched on here(but used and analyzed in xmitter/receiver implementations) • Frequency response: Gain & Phase “Distortion” EE350

  3. Some Terminology • Information source: supplies an analog signal in the form of a time-varying voltage or current that directly corresponds to the information. (baseband signal) • Audio • Telephone: 300Hz to 3.3kHz • AM broadcast: 100Hz to 5kHz • FM Broadcast: 50Hz to 15kHz • CD Audio: 20Hz to 20kHz • Scanned Video(Philo Farnsworth, electron beam, 1921) • NTSC: 6MHz EE350

  4. Terminology (2) • Transmitter: Puts the signal into a form that can traverse the channel . • Carrier: a simple waveform that is compatible with the channel. • Usually a sine wave • Transmission line: Coaxial cable, Twisted Pair • Free space: Electromagnetic Wave • Can be a light beam (or ultrasound) • Free Space: Laser • Fiber Optics: What keeps the light inside the fiber? EE350

  5. Terminology (3) • Modulation: vary a parameter of the carrier in proportion to the baseband information signal. • AM: amplitude modulation • FM: frequency modulation (Colonel Edwin Armstrong)(closely related to phase modulation) • Receiver: recovers an estimate of the original information baseband signal from the corrupted (by the channel) transmitted signal. • Demodulation: the inverse of the modulation process, sometimes called detection. Armstrong with an early superhetrodyne receiver EE350

  6. Terminology (4) • Channel: The medium through which the signal travels. • Additive noise: Interferes with the desired signal • “White noise”: Random (unpredictable) signal with equal energy at all frequencies • Gaussian noise: values distributed according to the “bell” curve • Non-linear distortion: Usually ignored in schoolwork, not here • Time variation: Variations in transmission delay and gain, not dealt with here • Frequency response: sometimes due to “reflections” or echoes • Gain variation with frequency • Phase variation with frequency: • Linear phase: just a fixed delay • Phase distortion: different propagation delay at different frequencies EE350

  7. Terminology (5) • Multiplexing:The sharing of a high capacity channel • Time-Division Multiplexing • Fast channel; Slow signals • Sampling: Represent a continuous signal as a sequence of narrow pulses (PAM) • Frequency-Division Multiplexing • Wide bandwidth channel; Narrow bandwidth signals • Modulation: move each signal to a different frequency range • Demodulation: recover a particular baseband signal EE350

  8. Course Description • DoctorD’s Web Site: http://doctord.webhop.net • Syllabus • Schedule (updated often) • Texts: cover both EE350 and EE352: Digital Communications • Haykin, “Communication Systems”, Wiley, 2001 • Hsu, “Analog and Digital Communications”, Schaums Outlines, 2003 • References: Web • Class Contact List • Learnlinc: http://learnlinc2.ffldusoe.edu/learnlinc/ EE350

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