Seminars

Currently the DSS group offers only one seminar. You can find some details below.

Selected Topics in Digital Signal Processing

Talk Schedule

Topics offered in WS 17/18

Speech and Audio:

1. Evaluation Strategies for Speech Communication Systems

   Modern speech communication systems, such as mobile phones or In-Car-communication-systems (ICC-Systems), use various algorithms to improve the intelligibility and quality of the transmitted speech signals. These systems are also often used in disturbed environments. In order to make different systems comparable to each other or to document the progress of enhancement, evaluation strategies and tests are required. In this context, an overview of the evaluation strategies should be given.

2. Noise Classification

   Transmitted speech signals are often corrupted by noise. While this noise may, of course, be the background noise of the original recording environment, the noise may also be a byproduct of the transmission system. The classification of the noise characteristics into a fixed number of noise types may then both aide the noise reduction on the recording-side and the transmission system analysis on the listening-side. Aim of this report is to outline existing classification approaches and to rank them in terms of accuracy und discriminatory ability.

3. Kalman Filter based Feedback Compensation

   A well know method in the acoustic echo control is the Kalman Filter based approach. In this project the student should investigate how such method can be adapted to be used in a closed acoustic loop to compensate feedback.

Medical Applications:

4. Collision Testing for Peripheral Nerves and Typical Distribution of Conduction Velocities from a Signal Analysis Point of View

   The electrical signal of a peripheral nerves is quite low. Peak amplitudes in the range can be achieved by using an external electric stimulation of the nerve. The Electroneuography (ENG) is the current gold standard of nerve assessment to investigate the nerve conduction velocity of a human. Collision testing is a very old but also interesting technique to further enhance this standard diagnostic. Furthermore it helps to describe the complete population conduction characteristic of a nerve. This technique and also typical distributions of conduction velocities of humans should be investigated from a signal analysis point of view in this seminar.

5. Source Separation using Decorrelation-Independent Component Analysis for the Application in Biomagnetic Multi-Channel Measurements

   MIMO biomagnetic sensor signals are a superposition of several biological sources and additive noise. For evaluation of the biological source signals the sensor signals have to be separated and analyzed. One method for separating the source signals is the time-delayed decorrelation-independent component analysis. The purpose of this report should be the explanation of the functioning of the algorithm and the usage for biomagnetic signal sources.

Underwater Applications:

6. Calibration Methods for MIMO SONARs

   In theoretical derivations, array elements are often assumed to be ideal. For real arrays, however, there can be severe differences in amplitude and phase between multiple elements. These differences have a negative impact on the utilized signal processing algorithms (e.g. beamforming) and, thus, on the performance of SONAR systems. For this seminar topic, different calibration techniques which mitigate the negative influence of non-ideal element behavior are to be studied. To do so, possible causes (besides production tolerances) for such a behavior also need to first be identified.

7. Underwater Channel Estimation

   In future underwater communication systems the channel estimation will be a crucial part of the system. Because of damping and dispersion high-frequency communication is not usable for longer distances underwater, therefore the so called underwater acoustic channel (UAC) seems to be the best candidate to fulfill the requirements for distance and datarate. Unfortunately, the underwater acoustic channel is one of the most challenging channels in the world due to its time varying and frequency-selective characters and these characters make channel estimation a compulsory task for coherent orthogonal frequency division multiplexing (OFDM) underwater communication.

8. Position Determination of Surface Vessels

   In the present days the position determination of surface and underwater vehicles represents a challenge in the navigation. In this seminar topic, different position determination methods are to be studied, the advantages and disadvantages, as well as the most important influencing factors are to be worked out.

9. Statistical Hypothese Testing on the Example of Target Detection

   The evaluation of the statistical raw data depends always on the description of the mathematical context and the statistical properties of these data. The result of the evaluation may depend on different approaches. In the context of radar and SONAR applications there are some parts of the applied statistics that can be used to detect targets in clutter. The talk is of statistical hypotheses and statistical tests. In this seminar topic, the preparation steps for the evaluation of the raw data are to be studied.