Analysis and Implementation of a Novel Single Channel Direction Finding Algorithm on a Software Defined Radio PlatformJohn Joseph KeavenyCapter1A radio direction finding (DF) system is an antenna array and a receiver arranged in a combination to determine the azimuth angle of a distant emitter. Basically, all DF systems derive the emitter location from an initial determination of the angle-of-arrival (AOA).Radio direction finding techniques have classically been based on multiple-antenna systems employing multiple receivers. Classic techniques such as MUSIC 12 and ESPRIT use simultaneous phase information from each antenna to estimate the angle-of-arrival of the signal of interest. In many scenarios (e.g., hand-held systems), however, multiple receivers are impractical. Thus, single channel techniques are of interest, particularly in mobile scenarios. Although the amount of existing research for single channel DF is considerably less than for multi-channel direction finding, single channel direction finding techniques have been previously investigated.When considering single channel direction finding systems, we find that there are two distinct types of DF systems. The first type of DF system is the amplitude-based DF system. Amplitude-based systems determine the bearing of the signal (or the AOA) by analyzing the amplitudes of the output voltages from each antenna element. Amplitude DF systems include the Watson-Watt technique using an Adcock antenna array .The second type of DF system is the phase-based DF system. Phase-based systems use three or more antenna elements that are configured in a way so that the relative phases of their output voltages are unique for every wavefront angle-of-arrival. Phase-based DF systems include the Pseudo-Doppler technique with a commutative switch based antenna array .Since both of the above techniques are primarily analog techniques and have been analyzed in previous work, we will investigate a new single channel direction finding technique that takes specific advantage of digital capabilities. Specifically, we propose a phase-based method that uses a bank of Phase-Locked Loops (PLLs) in combination with an eight-element circular array. Our method is similar to the Pseudo-Doppler method in that it samples antennas in a circular array using a commutative switch. In the proposed approach the sampled data is fed to a bank of PLLs which tracks the phase on each element. The parallel PLLs are implementedin software and their outputs are fed to a signal processing block that estimates the AOA.This thesis presents the details of the new algorithm and compares its performance to existing single channel DF techniques such as the Watson-Watt and the Pseudo-Doppler techniques. We also describe the implementation of the algorithm on a DRS Signal Solutions Incorporated (DRS-SS), WJ-8629A Software Definable Receiver with Sunrise . Technology and present measured performance results. Simulations on a signal with 10dB SNR have shown that the Watson-Watt algorithm and the Pseudo-Doppler algorithm have an accuracy that is worse than the proposed technique by approximately an order of magnitude.The algorithm was implemented on a single-channel DSP-based software radio with a homemade eight-element circular antenna array. The WJ-8629A software defined radio receiver was provided by DRS-SS in order to implement our algorithm. The implementation was tested using a CW signal at 1.57068 GHz in a low multipath laboratory environment and outdoors. The performance of the prototype is compared to the data provided by the simulations in Matlab.Implementation results focus on CW measurements in a relatively benign laboratory environment for proof-of-concept testing. This document will show that the basic version of the algorithm can result in a significant computational burden, thus we investigate a low-complexity approach and demonstrate its performance. It will be shown that a significant computational reduction can be achieved with minimal performance penalty.1.1 Software IntroductionDuring our research, all of the single-channel direction finding simulations were performed using the MATLAB 6.1 software. After the simulations were completed, the MATLAB code was then ported to hardware for implementation using the C programming language. The initial C programs were written and tested to prove that the algorithms could be implemented on the TI based software radio. After the C programs were tested and compared to their Matlab counterparts, they were then optimized for the Texas Instruments TMS320C67x Digital Signal Processor.1.2 Hardware Introduction1.2.1 DRS Signal Solutions, Incorporated WJ-8629A Software Definable Receiver with Sunrise. TechnologyThe implementation was performed on a Texas Instruments DSP-based WJ-8629A software defined radio provided by DRS-SS. It has a frequency range from 20 to 2700 MHz with 10-Hz resolution, receiver filterin