Signals, Systems and Modulations

Lectures

• Signals in telecommunications (2h): Examples, properties and mathematical models of signals in telecommunication. General model of communication link (modulator – channel - demodulator). Analog and digital modulations, multiplexing (TDM, FDM). Criteria used for comparing modulations: bandwidth, bit rate, signal to noise ratio, immunity to channel noise.
• Description and processing of analog signals (2h): Signal analysis in time and frequency domain, LTI systems, stability.
• Discrete signals and systems (8h): Sampling of the baseband and passband signals. Z-transform and inverse Z-transform. Discrete Fourier Transform. Discrete systems: impulse response, frequency response, stability conditions.
• Introduction to adaptive filtering (4h): A problem of signal prediction, noise suppression, echo cancellation. The Wiener filter, adaptive filters.
• Introduction to signal compression (2h): Problem of source coding, lossless and lossy compression. Example of a lossy compression – the Huffman code. Lossy compression: using a predictor, digital transforms (DFT, DCT).
• Analog modulations (2h): Amplitude modulations (DSB-SC, DSB, SSB, VSB) and angle modulations (FM, PM): spectra of modulated signals, bandwidth, detection methods, immunity to channel noise.
• Digital modulations and transmission codes (2h): Transmission codes and their spectra (unipolar code, bipolar code, AMI, etc.). Basic digital modulations: ASK, FSK, PSK – spectra of the modulated signals. Mixed modulations: AM-PM, QAM. Differential coding: DPSK.
• Reception of digital signals (3h): Channel with additive gaussian noise. Optimal reception of binary signals: unipolar, bipolar, PSK, FSK. The quadrature receiver for M-ary PSK and AM-FM signals. Coherent and noncoherent reception of DPSK signals. Comparison of digital modulations.
• Digital transmission of analog signals (3h): Quantization, quantization error, SNR. Nonuniform quantizers, logarithmic quantizers. ITU-T standard PCM 64kbit/s – channel bandwidth, SNR, influence of channel noise.
• Limits of transmission (2h): Maximum baud rate (Nyquist theorem). Channel capacity – Shannon theorem and its consequences.

Tutorials

• Analysis of analog signals (2h): Fourier transform, LTI systems, stability.
• Discrete time signals and systems (review) (4h): Calculation of Z-transforms and inverse Z-transforms. Calculation of a frequency response of a system, given its transfer function in Z domain. Stability of discrete systems.
• Adaptive filtering (2h): Predictor, echo canceller and noise suppression algorithm.
• Reception of AM and FM signals (2h): calculation of signal and noise power in a synchronous detector, envelope detector and frequency discriminator. Analysis of a phase modulator for SSB. Comparison of analog modulations.
• Optimal reception of digital signals (2h): Evaluation of BER for binary transmission in the channel with AWGN.
• Quantization (2h): Evaluation of a SNR for the uniform and nonuniform quantizer. Comparison of the PCM with analog modulations (channel bandwidth, influence of the channel noise on the output signal quality, etc.).

Laboratory

• Sampling and discrete transforms (2h): Simulation of sampling of sine and audio signals. Verification of sampling theorem. Comparison of DFT and DCT.
• Discrete filters (2h): Simulations of FIR and IIR filters. Comparison of their properties.
• Adaptive filtering (2h): Testing of prediction, echo cancellation and noise suppression algorithms.
• Transmission codes (2h): Hardware part: comparison of the bipolar code receivers. Software part: construction of decision algorithms for binary baseband transmission.
• Digital modulations (2h): Comparison of binary and M-ary modulations, the quadrature receiver, coherent and noncoherent reception of DPSK.
• Quantization and ADPCM (2h): Presentation of the PCM and DPCM: sampler, quantizer, predictor. SNR for an uniform, nonuniform and adaptive quantizers. Measurement of prediction gain in ADPCM.

During the lab exercises it is possible to score up to 30 points (5
pts per one session)

Maximum score for the exam is 70 points. There are also up to 10 points
to get during the tutorials.

The final result is based on the following pattern:

A: 91-110 points

B+: 81-90 points

B: 71-80 points

C+: 61-70 points

C: 51-60 points

D: 0-50 points