| Passive positioning technology,due to its important role in battlefields,has received attention from all countries in the world.Sound source location technology is one type of passive location technology.It uses sounds from target sound source for positioning and tracking.Currently,sound source localization is mostly used to locate sources within close distances,and the positioning coordinates are calculated using relative coordinates of the fixed microphone array.This application model causes inconveniences to track a sound source while the tracker is in move.To solve this problem,this paper designs a high-accuracy GNSS-based sound source localization method,where the coordinates of the array microphones are calculated with precision in real time.The system can be used not only for battlefields,but also for security,surveillance,and rescue missions.Work in this thesis combines sound source localization algorithms and satellite positioning technology,using a high-precision GNSS positioning system to determine precise locations of the microphones,thus is able to be carried by a moving sound tracker.When the microphone array consists four microphones or more,the TDOA method can be used to calculate the sound delay.By utilizing the MIC coordinates and the estimated delay,the target sound source can be located by its latitude,longitude,and height.The thesis is organized as below,first,principles of satellite positioning and sound source location using TDOA method are reviewed.Error analysis and Matlab simulation of TDOA algorithm are then carried out,and an improved two-step GCC delay calculation method is proposed for long distance TDOA sound source localization.Using the envelope of the sound signal,a rough delay is estimated using a lower sampling rate as the first step and rough delay was then shifted.After that,a higher sampling rate is applied to ensure a high accuracy.The two-step GCC algorithm achieves good accuracy with reasonable computational cost.Secondly,the hardware design was implemented for the prototype system.The prototype consists a sound collection module and a satellite positioning module,a storage module,a system control and position calculation module,and a display module.Among them,the satellite positioning unit uses the high-accuracy three-system seven-band positioning board UB3 80 from Unicorecomm.The control unit employs STM32F103 VET6 as the main control chip.Finally,various modules are integrated to form a prototype of a sound source location system based on high-accuracy GNSS.The thesis work also includes software design of the whole system,and accuracy analyzation of the system.The system can realize sound source localization for short and medium range scenarios. |
