Direction Finding : Determine the direction to a transmitter with randomly placed sensors

Abstract: There are a lot of stand-alone and mobile platforms using transmitters today. Some want to be found while others do not. In our modern society there is a great demand of mobility and communication abilities. This means that several mobile platforms could potentially carry a sensor to record incoming signals to be used in Direction Finding. This thesis identifies the possibility to determine the direction to a transmitter with randomly placed sensors. By conducting a literature review well-known methods such as Time Difference Of Arrival (TDOA) and MUltiple SIgnal Classification (MUSIC) where chosen as methods in this analysis. The methods are applied on two antenna arrays, an Uniform Circular Array (UCA) and a Random Circular Array (RCA). The RCA is generated with randomly placed sensors. The performance in the Direction Of Arrival (DOA) is investigated in presence of time synchronization error and with different numbers of elements, radius and Signal to Noise Ratio (SNR). The ambiguity in the arrays is also investigated to insure a ambiguity-free DOA estimation. The results from this analysis identifies that the accuracy in the DOA estimation is dependent on the number of elements, SNR, the elements positions and the radius of the DF array. Furthermore, the accuracy of a UCA is greater than a RCA when the elements are randomly distributed within the area of a circle with radius R. Finally, it has shown that if time synchronization error occurs between the sensors, then the MUSIC method the accuracy will decrease greatly.