Invalidity dossier
US 5554982
Wireless train proximity alert system
Current assignee: Raytheon Co
Added 9/23/2026, 11:00:47 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US5554982A
Title: Wireless train proximity alert system
Patent number: US5554982A | Application: US08/283,460 | Inventors: Keith L. Shirkey, Bruce A. Casella
Assignee: Original assignee Hughes Aircraft Co; current assignee listed as Raytheon Co (as listed by the source; not a legal conclusion).
Dates: Filed 1994-08-01; priority date 1994-08-01; granted/published 1996-09-10. Anticipated expiration 2014-08-01; status "Expired – Fee Related."
Purpose: To provide a wireless train crossing warning system that accurately estimates a train's time to arrival, controls the size of the warning zone, warns individual drivers in time, deactivates the warning zone after the train passes, provides a vehicle identification code, and includes a backup system. It aims to reduce false alarms that could cause drivers to ignore true warnings, and to allow verification/tracking of events (including confirmed reception of a warning).
Plain-language scope: A train (or trackside) transmission device sends a train proximity signal, preferably including the train's speed and position. A crossing-based transceiver receives it and transmits warning-zone boundary coordinates when the train's estimated time-to-arrival is within a predetermined range. A vehicle-based receiver uses GPS to determine the vehicle's position and speed and produces an alarm when the vehicle is inside the warning zone and within a distance-to-crossing range that depends on vehicle speed. The warning zone inhibits alarm activation until the vehicle is inside it, reducing false alarms. Embodiments include train-mounted or trackside transmitters, a crossing "Warning and Verification System" with handshake signal, TDD sensors (preferably short-range doppler radar or optical) to deactivate the zone after the train passes, and vehicle alarms such as a blinking light and beeper. Classifications include B61L29/24, B61L29/246, G08G1/16, and B61L2205/04 (GPS).
Source: https://patents.google.com/patent/[US5554982](/patent/US5554982)/en
What the excerpt does not establish: It does not establish claim wording, the full specification, exact numbers/figures, or the omitted description text. It does not establish litigation, ownership transfers, validity, or prior-art conclusions.
Generated 10/1/2026, 9:33:00 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Derivative works
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