Tentin tekstisisältö

Stekanus AEInno wm vurmareee
stefanus. wirdatmadjo Etut.fi

TLT-5206 COMMUNICATION THEORY Midterm Exam 04.12.2012

Prepared by M.Valkama, no materials, no calculators

(Suomenkieliset kysymykset paperin toisella puolella)

Sampling of signals. Present the time domain mathematical model for ideal sampling
process. Given the spectrum of a continuous-time signal, sketch (i.e., draw) also the
corresponding spectrum after ideal sampling. Based on that, formulate the basic
reguirement in order to avoid aliasing. Explain also the basic idea of reconstruction in
both time and freguency domains. Finally, tell the basic idea of sub-sampling principle in

bandpass signal context.

Information theoretic basis of communications. Explain the concepts of information
and entropy. Give some examples. Explain also what mutual information means. Fxplain
further the concept of channel capacity and how is it related to mutual information
concept. How physical guantities like bandwidth, signal power and noise power affect the
capacity typically?

Digital transmission. Explain the concept digital transmission at conceptual level.
Explain how digital pulse amplitude modulation principle works. What are the key
Functionalities of transmitter and receiver in a digital baseband PAM transmission
system? What does Nyguist pulse-shaping mean? How does the bit rate depend on the
available bandwidth and other possible parameters? Explain also how I/O modulation is

combined to baseband PAM principle for radio communications purposes.

Maximum points: 3x5 = 15p.