US3758775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Railroad crossing signalling system
Assignee: Department Of Transportion
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Filing: 1971-09-29
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Granted: 1973-09-11
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Expires: 1991-09-29
Abstract
Abstract Disclosed is a highway-railroad crossing signalling system utilizing microwave telemetry to convey control information from a remote sensing location to a receiver coupled to an active motorist warning device.
Inventors
- 👤 J Hopkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:19
CPC Classifications
B; B61; B61L; B61L29/00; B61L29/24; B61L29/28; B61L29/282
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
157 words
A railroad crossing signalling system comprising: transmitter means for producing a beam of microwave energy for conveying train presence information; modulator means for modulating said beam, said modulator means comprising a sensor means having attenuator means for suppressing said beam when a train is sensed to detect the presence of trains at said displaced location and low duty cycle pulse modulator means for modulating said beam in response thereto; receiver means for receiving said beam of microwave energy and for detecting the presence or absence of trains according to the modulation characteristics of said beam; and active warning means responsive to said receiver means for warning motorists of the presence of trains detected by said detection means, said receiver means and said warning means are disposed adjacent a highway railroad-track crossing and said transmitter means is disposed at a substantially displaced location therefrom adjacent said railroad track and is coupled to said receiver means by said beam.
Claim 2
Dependent Claim
157 words
A railroad crossing signalling system comprising: transmitter means for producing a beam of microwave energy for conveying train presence information; modulator means for modulating said beam, said modulator means comprising a sensor means having attenuator means for suppressing said beam when a train is sensed to detect the presence of trains at said displaced location and low duty cycle pulse modulator means for modulating said beam in response thereto; receiver means for receiving said beam of microwave energy and for detecting the presence or absence of trains according to the modulation characteristics of said beam; and active warning means responsive to said receiver means for warning motorists of the presence of trains detected by said detection means, said receiver means and said warning means are disposed adjacent a highway railroad-track crossing and said transmitter means is disposed at a substantially displaced location therefrom adjacent said railroad track and is coupled to said receiver means by said beam.
Claim 3
Dependent Claim
30 words
A railroad crossing signalling system according to claim 1 wherein said receiver means comprises enabling means to enable said warning means in response to a sustained absence of said beam.
Claim 4
Dependent Claim
28 words
A railroad crossing signalling system according to claim 1 wherein said transmitter means, said receiver means and said warning means each comprise a separate self-contained power source means.
Claim 5
Dependent Claim
20 words
A railroad crossing signalling system according to claim 3 wherein each of said self-contained power source means comprises a battery.
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) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |