The main aim of this work is to demonstrate that communication- type equipment systems can effectively be simulated on a digital computer. A time domain digital simulator ICOSS is first developed. ICOSS provides a facility for interactive simulation of most receiver/transmitter types of communication structure, by specifying individual signal processing modules, each of which can be described mathematically. Simulation using ICOSS operates interactively where the user can construct, edit, change some of the parameters, run the program and look at the result in one simulation session. ICOSS, being a time domain digital simulator is capable of handling feedback operation and stochastic processes. The examples of simulation in this thesis are more inclined towards solving some of the practical problems encountered in developing certain communication equipment systems. The work also includes the investigation by computer simulation of some practical problems which are difficult or impossible to measure effectively in practice, but which can be investigated by means of computer simulation. The simulation results clearly show that system studies by simulation provide a simple and effective approach to system design before the final system is actually built in the laboratory. In the simulation process, the analytic signal lowpass equivalent is used because it is a powerful and cost effective modelling technique for communication system. The thesis begins in chapter one with the introduction of the modelling concept and various areas of simulation that can be applied in communication. Chapter two describes briefly the theory and operation of the phase locked loop and its fast acquisition technique, which are used in the simulation work of later chapters. Analytic signal and lowpass equivalent modeling techniques used throughout the simulation work are demonstrated at the beginning of chapter three. Chapter three also introduces ICOSS - the time domain interactive Communication System Simulator, developed at the School of Electrical Engineering, University of Bath. Its structure, implementation and operation are described. The development of ICOSS is tested by simulating practical systems, that is, a phase locked loop and its fast acquisition technique, and comparing the simulation and practical results as implemented in chapter four. The significance of the sampling frequency in computer simulation, and subsequently its effect on computer processing time and cost is also demonstrate in chapter four by carrying out various simulation tests. One of the main aims of modelling is to model a system with the minimum number of sample points, in order to reduce the amount of computation and hence valuable computing time. Chapter five investigates by simulation the effect of noise, a typical example of a stochastic process, on the performance of the phase locked loop and its fast acquisition loop. The results are compared with practical measurements. In a practical case, it is difficult to monitor and measure the loop performance at low signal to noise ratios, but it can be performed easily by using computer simulation. Chapter six simulates the effect of time delay on the acquisition performance of the phase locked loop and its fast acquisition technique. The effect of delay in the loop is particularly important because it is difficult and almost impossible to investigate effectively in a practical system. Chapter seven concludes by summarising the work and results of simulation of the preceding chapters, including future development of ICOSS. Appendix A provides a brief instruction guide to the use of ICOSS for future users. (Abstract shortened by UMI.).
|Date of Award||1981|