ENGINEERING TRIPOS PART IIA – 2012/2013

Module 3F4 – Data Transmission

COURSES:

Baseband Transmission, 2 lectures/week, weeks 1-4 Lent term, (Dr I.J.Wassell)
Digital Modulation, 2 lectures/week, weeks 5-8 Lent term, (Dr N.G. Kingsbury)

AIMS

Module 3F4 aims to cover a range of topics which are important in modern communication systems.  It extends the basic material covered in the Engineering Part IB Communications course to deal with data transmission over baseband (low frequency) channels, and data transmission over bandpass (higher frequency) channels.  The effects of noise are analysed in some detail.  Techniques for protecting coded information on channels subject to transmission errors are also covered.

SYLLABUS

Baseband Transmission (8L)

The communications system model and system characteristics. Inter-symbol interference and eye diagrams. The effects of noise and methods of calculating bit error probabilities. The use of pulse shaping for bandwidth control and reduction of inter-symbol interference. Techniques of line coding for control of the spectrum of the transmitted signal. Design of transmit and receive filters for optimum performance. Equalisation techniques to correct for undesirable channel characteristics.  Forward error correction coding.  Analysis of error control performance.

Digital Modulation (8L)

The use of phasors for dealing with digitally modulated bandpass signals and bandpass noise. Generalise use of phasors to represent analogue modulated signals and noise.  Spectral characteristics (bandwidth requirements) and bit error rate performance of digitally modulated signals; Binary Phase Shift Keying (BPSK), Binary Frequency Shift Keying (FSK), and Multi-level modulation techniques.  Digital TV example application.

OBJECTIVES

Baseband transmission

This course will cover topics relevant to transmission of data over baseband channels.  Students should:

• Be familiar with the basic elements of a baseband communication system (i.e. one which does not employ carrier waves) and appreciate the likely characteristics and imperfections of such systems.
• Know how inter-symbol interference degrades performance and how eye diagrams may be used to analyse these effects.
• Know how noise causes bit errors and be able to calculate the probability of error as a function of signal-to-noise-ratio.
• Appreciate that pulses may be shaped to control the bandwidth of a signal and reduce inter-symbol interference, and be aware of the limits on transmission rate if ISI is to be avoided.
• Appreciate the need for line coding, be aware of commonly used line codes, their applications and transmitted spectra.
• Design the filters in the transmitter and receiver so as to obtain optimum performance.
• Appreciate how equalisation can correct for undesirable channel characteristics and be able to design simple equalisers.
• Be able to use block codes to add redundancy to messages to control the effects of transmission errors.
• Know how to encode and decode messages using Hamming codes.
• Be able to determine the probability of decoding a message incorrectly, given the channel bit error probability, as a function of the error control strategy.

Digital Modulation

This course will cover topics relevant to the transmission of data over bandpass channels. Students should:

• Be able to use phasors to represent both the amplitude and phase of modulated signals.
• Be able to represent bandlimited noise by phasors and be aware of the properties of such noise phasors
• Understand and describe the principles of operation of binary modulation by FSK and PSK and multi-level modulation techniques.
• Be able to understand and describe the demodulation of digital bandpass modulated signals in noise.
• Be able to calculate the probability of error as a function of signal-to-noise-ratio.
• Be able to understand the operation of a broadcast digital TV system.

ASSESSMENT

Material: Format – Timing – Marks

Lecture syllabus. Written examination (1.5 hours) – Start of Easter term – 100%

REFERENCES

Please see the Booklist for Part IIA Courses for references for this module.