Doppler radar speed measurement on board - digital signal processing
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Abstract Doppler radars have been widely used in many different fields, such as traffic control, weather prediction, navigation, satellite tracking, Airborne Early Warning systems and missile guidance. The technology company Q-free in Trondheim intends to test the application of the Doppler radar module MDU 2410 in speed measurement. In this thesis a method was presented to measure the speed of a vehicle with this radar module.The most frequently used method to analyze the Doppler signal is spectrum estimation. This thesis concentrates on the discussions about the different algorithms for PSD estimation. Both the classical spectrum estimation methods, such as the periodogram, the Bartlett method, the Welch method and the BT method, and the modern PSD estimation methods like ARMA process, AR process and MA process, were introduced. The AR model is the most widely used among these three parametric models. There are two main reasons. Firstly, the AR model is suitable for representing spectra with narrow peaks. Secondly, the AR model results in very simple linear equations for the AR parameters. On the other hand, the MA model, as a general rule, requires many more coefficients to represent a narrow spectrum. Consequently, it is rarely used by itself as a model for spectrum estimation. By comparing the spectra of the AR model with the other spectra based on the classical spectrum estimations, the advantages of the AR model are obvious. The resolution is high; the ability of anti-interference is strong, and the peak value is clear. As a result it was determined that the AR should be implemented in this system.The measured results reveal that the order value in the AR model affects the accuracy of calculation results. To reach a precise velocity, the order should be dynamic in the calculations. After a series tests, the order is determined to begin with 23, and then decreases gradually when the velocity of the vehicle reaches 20 km/h. This thesis can be continued with further discussions on the AR model. There may be other methods for discovering the velocity with higher levels of accuracy.