The Principle Research and Implement of the Acoustic Keyboard for Computer
|School||Harbin Engineering University|
|Course||Circuits and Systems|
|Keywords||acoustic keyboard microphone array data acquisition time reversal|
With the development of computer technology, higher requests of the appearance and volume of computers are put forward. As an important component of computer, computer keyboard will be more simplify and portable.A new idea of acoustic keyboard for PC (personal computer) based on locating the typing sound is demonstrated in this paper. The acoustic keyboard is made by a piece of paper, called acoustic keyboard, printed characters compatible with the standard PC/104 keyboard. The typing sound from acoustic keyboard is picked up through the microphone array which is laid in front of the acoustic keyboard. And then through the signal conditioning circuit, after A/D converting, the signal is collected by DAQ Card (Data Acquisition Card). After that, through the near-field localization algorithm, the location of the typing sound source from the acoustic keyboard can be searched. After that, we get the typed character and its corresponding keyboard scan code by means of table-lookingup methods. Acoustic keyboard replaces traditional keyboard of desktop computer only by using a piece of paper. This not only saves costs but reduces the pollution and waste of destroying traditional keyboard raw material, which is important to environmental protection.First of all, the scheme of acoustic keyboard is proposed, and then design of acoustic keyboard and microphone array, signal conditional circuit, data acquisition and calibration of the array amplitude and phase errors are respectively introduced. Afterwards, software design of data acquisition and configuration of double card synchronization are analyzed in detail. In addition, a mathematical model for locating the typing key is established based on the time reversal mirror (TRM) technique. And then, the results through computer simulations and actual near-field acoustic source localization experiments show that the TRM algorithm can achieve high positioning accuracy. What’s more, we propose a solution to a shifted acoustic keyboard, which solve arbitrary placement of acoustic keyboard in practical application.Finally, we design an acoustic computer keyboard demo interface. Through the interface, one can easily observe the good effect of our localization algorithm. This will provide important foundation and theoretical guidance for the further research of acoustic keyboard.