Integrated circuits available today for high frequency applications make the realisation of HF-transmission systems a relatively easy task. The aim of our diploma thesis was the design and implementation of a complete wireless transmission system for composite video signals for distances of up to 50 m. Our system will be part of an engine simulator. The video camera will be mounted in a model engine. The images, as seen from the engineer in the model engine, will be transmitted to a fixed location.

Due to the limited space in the model engine, small mechanical dimensions were an important criterion for the design of the transmitter. Frequency modulation was selected to meet the specified high quality of the transmission. At a video bandwidth of 5 MHz and a peak deviation of 10 MHz we obtain a S/N-demodulation gain of 15 dB. The bandwidth of the modulated carrier is 30 MHz. Therefore we were forced to use the ISM band at 2.4 - 2.5 GHz. The maximum transmitter power permitted in this band by the Bakom is 10 mW. In order to guarantee the transmission up to a distance of 50 m we had to realise a very sensitive receiver.

In the course of our diploma thesis we realised the entire system. A modular concept enabled us to build and test individual blocks. The final system reached the stringent requirements concerning distance and image quality. Even at a distance of 50 m, this corresponds a free-space loss of 74 dB, the S/N ratio after demodulation is sufficient and nonlinear distortions are small enough to deliver an image without any visible impairments.

The design and development of the entire system would have been impossible during the 7 weeks available for the diploma thesis. Therefore the system design and some early developments had been performed during our first engineering project in the last semester.

In the context of the LokSIM project, we had to solve six partial tasks in our thesis "controlling of a model engine over a radio channel". At first we improved the transparent, asynchronous radio transmission. In order to increase the transmission speed we implemented a software for the configu-ration management of the radio modules. With this software, it is possible to access the memory of the radio modules in the radio box and the model engines. A further task was the realization of the supply for the electronics in the model engine. Into this current supply, we integrated a buffer for the supply voltage of the microprocessor so that the operating system will not fail with an interruption of the main supply voltage. Next, we developed a digital speed control for the model engine. Thanks to our knowledge in control theory, we were able to solve the stability problems encountered. We devised the concept and built a mouse-box as an optional task. With a mouse-box connected to the radio box it is possible to have limited control over a model engine. We produced and tested a functional prototype. Finally we successfully converted a pantograph of the model engine into a radio module antenna. We also replaced the original antenna of the radio box with our own design. The tests showed that the radio transmission still functions perfectly.

The project "engine simulator" is the result of a team effort.All manipulations executable from a real engine cab are sensed and transmitted to a computer. There they are analysed and the speed of the engine is calculated and transmitted to the model engine via radio. A video camera in front of the model engine captures the engineers view which is transmitted via radio to a video projector. Its image is projected onto a screen in front of the cab.In our diploma thesis we realised the complete microcontroller system (MC-System) for the engine cab as well as the necessary system software. The system has to read more than 30 sensors and activate more than 60 actors.We developed a small printed circuit that fits the size of HO-models and holds the MC, various lamp drivers, a signal sensor and other components. All MC applications are run by a multi-tasking system that we have developed during a previous project and improved in this project.In addition to the micro controller applications we have programmed the software "simulation of a RE 4/4 II" including a freely choosable load. Even external influences such as signals, track conditions, tunnel diameters and many more are taken into account in the simulation.As initiators of the entire project we were also responsible for its overall management.

The company Sulzer Innotec AG is interested in measuring signals of rotary machines. For the examination of these machines, oscillations related to the rotation angle are of primary concern. Signals as sampled by ordinary data acquisition systems provide equal time slots which are not meaningful for the usual measuremenents. The spectra evolving suffer from leakage effects and defocussing. These deficiencies can be prevented, by sampling the measuring signals not equidistantly with respect to time, but to the rotation of the machine.

A paper of Olaf Hermann, Sulzer Innotec AG, shows how a signal sampled with equidistant time slots can be transformed into samples that obey the law of equidistant angle slots. In a first approximation the angular speed of the machine is assumed to be constant. However, for fast changes of the angular speed this model is not suitable.

In this diploma paper a mathematical model for non-constant angular speed is set up in a first section. In a second part the results of a cubic interpolation proove to provide much better results. In the second section new interpolation kernels for the calculation of signals synchronous to the angle were examined. These posses better convergence characteristics than the common sinc-interpolation.

The algorithms were implemented in the programming language C. Attention had to be paid to the wish that the program structures are set up suitable for real time processing. Since C-functions can be merged in a simple manner in MATLAB, all tests were executed in Matlab.