Seinverwerker vir laser-Doppler anemometrie

• Main Author: Venter, Con-Vivier
• Published: 2014
• Subjects: Laser Doppler velocimeter; Signal processing
• Online Access: http://hdl.handle.net/10210/9497

M.Ing. (Electrical And Electronic Engineering) === A brief introduction to laser Doppler anemometry is given. Signal processing techniques for LOA are discussed with specific reference to the salient advantages and disadvantages of each. The abovementioned discussion motivates the use of adaptive filters as parametric spectral estimators for frequency ext~action from Doppler signals. Two adaptive algorithms ie. 'the least mean sqaures' (LMS) and the 'recursive least sqaures' (RLS), are discussed. Results of a real-time application of the LMS algorithm, as implemented on the TMS320-10, as well as the results from a full study of the Kalman algorithm are shown and discussed. The implementation of a digital signal processor to make the application of parametric spectral estimation to LOA viable is discussed under the following headings: analogue module; mathematical processor; communications module; storage an~ display unit. The system is based qn a eight bit converter with conversion rates ranging from the lower audio range to 20MHz. It has a versatile trigger system to facilitate easy capture of Doppler data. Captured data is stored in an onboard FIFO register and is available to the mathematical processing unit for spectral analysis. '/ The mathematical processing unit is a sixteen bit, multi-processor environment specifically implemented for parametric spectral estimation. The system comprises three TMS320-10 signal processors which are connected by means of a high speed parallel communications channel. Processed data is available to a display and storage system via a high speed interface card that interfaces the sixteen bit signal processor environment to the eight bit environment of the display device.