| 摘要 |
<p>The present invention may be used for detecting sound frequency signals emitted by warning devices of emergency vehicles. A sensor may sense a selected frequency signal spectrum and may be in communication with an initial detection stage to detect a frequency of approximately 600 Hz and approximately 1400 Hz within a specific time interval. A signal identification stage may be in communication with said initial detection stage and may have a digital signal processor programmed to identify a wail and yelp warning signal to compare said warning signal to a histogram stored in a memory to estimate the distance from the sound frequency signal. The signal identification stage may be maintained in a power save mode until activated by said initial detection stage upon detection of a warning signal.</p> |
