Communications: electrical – External condition vehicle-mounted indicator or alarm – Transmitter in another vehicle
Patent
1987-10-14
1989-09-05
Brigance, Gerald L.
Communications: electrical
External condition vehicle-mounted indicator or alarm
Transmitter in another vehicle
340925, 340906, 340944, 367197, G08G 100
Patent
active
048642975
ABSTRACT:
A siren detector for detecting siren sounds which precess at known yelp, wail and high-low warble rates within a selected frequency band. A transducer detects siren sounds and produces a corresponding electrical output signal. The output signal is filtered to reject signal frequencies outside the selected frequency band. The signal amplitude is monitored and varied as required to produce a constant amplitude output signal. The constant amplitude output signal is low pass filtered for detection of siren high-low sounds and is also low pass filtered for detection and output of precession signals which pass through a selected center frequency. Subsequent filters are provided for detecting signals which vary at the wail and yelp warble rates. Wail, high-low and yelp warble rate signals output by the various filters respectively trigger wail and yelp clock generators which in turn drive don't walk and red light output flip-flops respectively. Operation of the red light output flip-flop is controlled by a delay mechanism which provides a further filtration level to prevent false triggering.
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Hargrove J. Lloyd
Shaw Brian
Brigance Gerald L.
Tekedge Development Corp.
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