Patent US3772641A successfully refreshed from Google Patents.
US3772641A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-testing emergency automotive warning system
Assignee: Individual
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Filing: 1972-03-31
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Granted: 1973-11-13
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Expires: 1992-03-31
Abstract
Abstract An emergency signal transmitted by a transmitter in an emergency vehicle is received by a radio receiver in an automobile. The received signal is mixed with the output of a continuously operating local oscillator to produce at the receiver output a beat frequency signal which is detected to energize an alarm in the automobile. However, the absence of a signal at the receiver output energizes the alarm to provide a self-testing or fail-safe feature for the receiver.
Inventors
- 👤 H Grosser
- 👤 W Fehlman
- 👤 D Carlson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:43
CPC Classifications
G; G08; G08B; G08B1/00; G08B1/08; G08B29/00; G08B29/12; G08B29/14; G08B29/16
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
197 words
A self-testing receiving apparatus for a vehicular emergency warning system comprising: a. a first antenna mounted on a vehicle for receiving an emergency radio signal transmitted from a near-by transmitter, b. a radio receiver mounted in said vehicle and connected to said antenna, c. a local oscillator mounted in said vehicle and radiating from a second antenna a local radio signal different in frequency from said emergency signal, d. said local signal also being received by said first antenna to produce at the output of said receiver a beat signal having a frequency equal to the difference between the frequencies of said emergency and local signals; e. alarm means mounted in said vehicle, f. first circuit means coupled between said alarm means and the output of said receiver for blocking said local signal, but passing said beat signal to actuate said alarm means to indicate the reception of said emergency signal, and g. second circuit means coupled between said alarm means and the output of said receiver and responsive to the absence of both said beat and local signals at said receiver output for actuating said alarm means to indicate the absence of a receiver output signal.
Claim 2
Dependent Claim
197 words
A self-testing receiving apparatus for a vehicular emergency warning system comprising: a. a first antenna mounted on a vehicle for receiving an emergency radio signal transmitted from a near-by transmitter, b. a radio receiver mounted in said vehicle and connected to said antenna, c. a local oscillator mounted in said vehicle and radiating from a second antenna a local radio signal different in frequency from said emergency signal, d. said local signal also being received by said first antenna to produce at the output of said receiver a beat signal having a frequency equal to the difference between the frequencies of said emergency and local signals; e. alarm means mounted in said vehicle, f. first circuit means coupled between said alarm means and the output of said receiver for blocking said local signal, but passing said beat signal to actuate said alarm means to indicate the reception of said emergency signal, and g. second circuit means coupled between said alarm means and the output of said receiver and responsive to the absence of both said beat and local signals at said receiver output for actuating said alarm means to indicate the absence of a receiver output signal.
Claim 3
Dependent Claim
76 words
A self-testing receiving apparatus as defined in claim 1 wherein said local signal frequency is close to said emergency signal frequency, and wherein said first circuit means comprises: a. frequency selective circuit means responsive only to the beat frequency for producing a alarm signal, and b. normally open relay means connected between said frequency selective circuit means and said alarm means, c. said relay means being closed by said alarm signal to actuate said alarm means.
Claim 4
Dependent Claim
65 words
A self-testing receiving apparatus as defined in claim 2 wherein said second circuit means comprises a normally closed relay coupled between said alarm means and the output of said receivers, said normally closed relay means being opened by the presence of a receiver output signal, whereby the absence of said receiver output signal causes said normally closed relay to close and actuate said alarm means.
Claim 5
Dependent Claim
35 words
A self-testing receiving apparatus as defined in claim 2 wherein said first circuit means further comprises a holding circuit for maintaining said relay means closed after it has been initially closed by said alarm signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-12 | 1977-05-14 | 1977-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-12 | 1981-05-14 | 1981-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-12 | 1985-05-14 | 1985-11-13 | $7700.00 | Window Closed / Lapsed |