Acoustic alert sensor

Claim 2

An acoustic alert detector for detecting an acoustic signal produced by a vehicle, said detector comprising: sensing means for sensing acoustic signals providing a first signal having a zero reference; first counting means for counting a first predetermined number of crossings by said first signal of said zero reference, and for providing a second signal upon said first predetermined number of said crossings by said first signal of said zero reference being counted; second counting means for counting a second predetermined number of said second signals, and for providing a third signal upon said second predetermined number of said second signals being counted; first timing means for permitting said second signal to pass to said second counting means after a first predetermined time; second timing means for resetting said first counting means after a second predetermined time, said second predetermined time being greater than said first predetermined time; and third timing means for resetting said second counting means after a third predetermined time.

Claim 3

The acoustic alert detector of claim 1 further comprising a rapid increasing signal detector, wherein said sensing means provides said first signal to said rapid increasing signal detector, and said rapid increasing signal detector comprises: full wave rectifying means for rectifying said first signal and providing a fourth signal; short-term averaging means for averaging said fourth signal and providing the average of said fourth signal as a fifth signal; long-term averaging means for averaging said fifth signal into a sixth signal; and threshold means for comparing said fifth and said sixth signals and permitting said second signal to pass.

Claim 4

The acoustic alert detector of claim 1 further comprising a high frequency burst detector for counting said zero crossings and resetting said first counter if said high frequency burst detector detects a predetermined number of said zero crossings in a fourth predetermined time.

Claim 5

The acoustic alert detector of claim 3 further comprising detector means for detecting a seismic signal, said acoustic alert detector providing a fourth signal if said third signal and said seismic signal are present.

Claim 6

The acoustic alert detector of claim 3 further comprising: a threshold detector for detecting the magnitude of said first signal; third counting means, said threshold detector providing said first signal to said third counting means if said magnitude of said first signal is above a predetermined magnitude, said third counting means for counting a third predetermined number of said first signals crossings of said zero reference and for providing a fourth signal when said third predetermined number is reached; fourth counting means for counting a fourth predetermined number of said fourth signals and for providing a fifth signal upon said fourth predetermined number of said fourth signals being counted; fourth timing means permitting said fourth signal to pass to said fourth counting means after a fifth predetermined time; fifth timing means resetting said third counting means after a sixth predetermined time, said sixth predetermined time being greater than said fifth predetermined time; and sixth timing means resetting said fourth counter after a seventh predetermined time.

Claim 7

An acoustic alert detector for detecting an acoustic signal produced by a vehicle, said detector comprising: an acoustic sensor for sensing acoustic signals providing a first signal with a zero reference; a zero crossing detector for producing a first pulse when said first signal crosses said zero reference; a first counter for counting said first pulses, said first counter providing a second pulse when said first counter counts first predetermined number of said first pulses; a second counter for counting said second pulses, said second counter providing a third pulse when said second counter counts a second predetermined number of said second pulses; a first timer permitting said second pulse to pass to said second counter after a first predetermined time; a second timer for resetting said first counter after a second predetermined time, said second predetermined time being greater than said first predetermined time; and a third timer for resetting said second counter after a third predetermined time.

Claim 8

An acoustic alert detector for detecting an acoustic signal produced by a vehicle, said detector comprising: an acoustic sensor for sensing acoustic signals providing a first signal with a zero reference; a zero crossing detector for producing a first pulse when said first signal crosses said zero reference; a first counter for counting said first pulses, said first counter providing a second pulse when said first counter counts first predetermined number of said first pulses; a second counter for counting said second pulses, said second counter providing a third pulse when said second counter counts a second predetermined number of said second pulses; a first timer permitting said second pulse to pass to said second counter after a first predetermined time; a second timer for resetting said first counter after a second predetermined time, said second predetermined time being greater than said first predetermined time; and a third timer for resetting said second counter after a third predetermined time.

Claim 9

The acoustic alert detector of claim 6 further comprising a rapid increasing signal detector, wherein said sensing means provides said first signal to said rapid increasing signal detector, and said rapid increasing signal detector comprises: a full wave rectifier for rectifying said first signal and providing a fourth signal; short-term averaging means for averaging said fourth signal and providing the average of said fourth signal as a fifth signal; long-term averaging means for averaging said fifth signal into a sixth signal; and threshold means for comparing said fifth and said sixth signals and permitting said second signal to pass.

Claim 10

The acoustic alert detector of claim 6 further comprising a high frequency burst detector for counting said zero crossings and resetting said first counter if said high frequency burst detector detects a predetermined number of said zero crossings in a fourth predetermined time.

Claim 11

An acoustic alert detector for detecting an acoustic signal produced by a vehicle, said detector comprising: sensing means for sensing acoustic signals providing a first signal having a zero reference; first counting means for counting a first predetermined number of crossings by said first signal of said zero reference, and for providing a second signal upon said crossings by said first predetermined number of said first signal of said zero reference being counted; and second counting means for counting a second predetermined number of said second signals, and for providing a third signal upon said second predetermined number of said second signals being counted, said third signal being an alert signal.

Claim 12

An acoustic alert detector for detecting an acoustic signal produced by a vehicle, said detector comprising: sensing means for sensing acoustic signals providing a first signal having a zero reference; first counting means for counting a first predetermined number of crossings by said first signal of said zero reference, and for providing a second signal upon said crossings by said first predetermined number of said first signal of said zero reference being counted; and second counting means for counting a second predetermined number of said second signals, and for providing a third signal upon said second predetermined number of said second signals being counted, said third signal being an alert signal.

Claim 13

The acoustic alert detector of claim 9 further comprising: first timing means for permitting said second signal to pass to said second counting means after a first predetermined time; second timing means for resetting said first counting means after a second predetermined time, said second predetermined time being greater than said first predetermined time; and third timing means for resetting said second counting means after a third predetermined time.

Claim 14

The acoustic alert detector of claim 10 wherein said sensing means comprises a microphone, said microphone sensing said acoustic signal and providing said first signal.