Abstract: 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.

Abstract: The emergency vehicle alert system may be used for detection of selected sound frequency signals emitted by warning devices of vehicles. A sensor may sense a selected sound frequency signal spectrum and may be in communication with multiple operational amplifiers. The operational amplifiers may be biased to detect a warning device sound source within 50 feet and within 1,500 feet of the sensor. The detection of a warning device sound source may be communicated to a warning indicator to activate the warning indicator.