Helicopter Sound Signal Recognition

AbstractThe intelligent mine will be the most important weapon system to defend arming helicopter in future war. American, Russian, and some other countries have developed this kind of mine and armed it in army. Our country began to research since the last part of 20th century, and will get into process of type梤esearch. The intelligent mine recognizes target by means of acoustic detection.The properties of acoustic field of the helicopter flying in air was studied first in this dissertation. Sound of the helicopter flying in battle field was detected and analyzed. The methods including acoustic energy detection , spectrum analysis, AR spectrum estimation , zero through rate of high frequency tone were used to extract target?s properties to approach object recognition, according to the properties that the sound of helicopter is composed of high frequency tone mainly and its spectrum is composed of a high frequency tone and a low frequency tone. Specially AR sepetrum estimation is analised mainly.Since the precise of AR spectrum is largely decided by self correlation function, this dissertation gives some method to improve the precise. Low pass filter is used to get rid of the disturb of high frequency ,windows is added to limited the port effect and finity lengtheffect,authority is used to intercept.To raise the speed of calculation, DSP chip is designed into circuit. DSP can calculate FFT in several millim梥econd. Also a method which can cooperate with mutiPU is advised at the last.