The Design And Implementation Of The Acoustic Keyboard Half-practically System

The humanity and simpleness of the computer is demanded more and more as the development of the computer technology. Minishing the computer's weight and volume will be an important development direction in future. Keyboard, which is an indispensable equipment of the computer, will develop along this direction as well.Considering the application background and development direction of the keyboard, a new idea of acoustic keyboard is proposed. In our idea, a piece of paper is used, which is called paper keyboard, printed characters, whose layout is the same as that of the standard PC104 keyboard, and a microphone array is adopted to capture the sound signal generated by typing certain character on the paper keyboard, then the sound signal is processed to gain the typed character. Finally, the character is embedded in the operating system of computer to complete the information input.The main intention of this paper is to design and implement a half-practically system of acoustic keyboard based on PC to validate the feasibility of the acoustic keyboard.The microphone array model and the related location algorithms in near-field are introduced. To reduce the influence inflicted on the location algorithms by the existing gain and phase error of the array, a new calibration method aiming at the uniform microphone array in near-field is proposed which is improved from the antenna calibration methods in far-field., a single signal source is used in this method, and it has been applied to the calibration of the actual microphone array.The whole structure of the half-practically system is introduced and the functions and design methods of its constituent parts are analysed as well. An NI DAQ card PCI-6024E is adopted to design the multi-channels data acquisition system of the microphone array. Considering that the PCI-6024E can not simultaneously sample the multi-channels signals, then an engineering solution is proposed to compensate it. Furthermore, the synchronization between two DAQ cards is discussed. Finally, the software of the half-practically system is discussed in detail and the design flow and illustrations are shown also.The problems emerged in the debug process are discussed and the acoustic keyboard half-practically system is evaluated, the result is satisfied. The system will play an important role in the research of passive acoustic location in near-field and the performance validation of the acoustic keyboard.