Title: Emergency radio frequency warning device

Abstract: An electronic whistle in the form of broad band radio frequency interference generator. A broad band generator generates a coherent or random noise signal which is modulated by an audio signal which corresponds to an audible warning signal such as a whistle or a siren. The modulated signal is then utilized to modulate a carrier signal and amplified and transmitted so that the radios in vehicles in the immediate area will receive an audible interference signal regardless of the particular channel to which the radio is tuned. The audible interference signal may be an intelligible reproduction of the input audio signal so that the driver of the vehicle can determine whether the warning signal is generated by a train whistle, a siren or a human voice.

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Inventors: Sadler, William S. (St. Paul, MN, US)

Application Number: 485761
Filing Date: 1974-07-03
Publication_date: 1976-04-06
Assignee:
Primary Class(es): 455/1 340/901, 340/902, 455/102
Other Classes:
US Patent Ref:

2448055	Aug, 1948	Silver et al.	325/35.
2885543	May, 1959	Williams	325/132.
2994765	Aug, 1961	Adam	325/131.
3517388	Jun, 1970	Vermillion	325/132.
3660811	May, 1972	Vail et al.	325/132.

Other Refs:
Primary Examiner: Griffin, Robert L.
Assistant Examiner: Ng, Jin F.
Attorney: Haynes; James D.