一种基于DSP的忙音检测设计

Design on a Busy Tone Detection Based on DSP

忙音是某一频率单音和静音交互出现的一种提示音。在实际应用中,当通话中有一方挂断电话,在某些情况下需要另一方自动把电话挂断,或当一方呼叫另一方,对方占线时,需要呼叫方实现自动重拔的功能,这时就需要对忙音进行检测。提出了一种基于DSP的忙音检测方法,当单音通过DSP的陷阱滤波器时,能量幅度会大幅衰减,从而能够判断是否存在单音。忙音具有单音和静音是交互出现并且持续时间相同的特点,通过一定时间内周期计数的方法可以确定单音和静音所占的比例,根据比例确定是否存在忙音。方法经电话实验验证可行,能够准确检测出不同类型的忙音。

Busy tone is a kind of prompt tone made up of the single tone and the mute tone,in which the two tones occur interactively. In practical application,when one hangs up,the other side of the call needs to auto hang up; when the line is busy,the caller side needs to auto redial. In order to achieve the auto ring off and auto redial,the detection of busy tone is necessary. A method of busy tone detection base on DSP is proposed. The single tone is detected because the energy of the single tone will decline substantially while the trap filter is used. The busy tone is characterized by interactive occurence of the single tone and mute tone and their same duration time. So it can be detected by counting the number of single tone and mute tone in the period and determining their proportion. After experimental verification,the method can detect different busy tone exactly.