Invalidity dossier
US 6759948
Added 9/24/2026, 2:10:36 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 6759948 B2
Title: Railroad collision avoidance system and method for preventing train accidents.
Patent number / application: US 6759948 B2, from application US 09/960,820.
Assignee: Time Domain Corporation (original assignee; listed current assignee is Time Domain Corp).
Inventors: William T. Grisham and Mark D. Roberts.
Key dates (as listed): Priority date 2001-09-21; filed 2001-09-21; published as US 20030058131 A1 on 2003-03-27; granted 2004-07-06; adjusted expiration 2022-03-11. Legal status listed as "Expired – Fee Related." Google notes legal status and dates are assumptions, not legal conclusions.
Purpose (per the supplied text): The invention "generally relates to the railroad field and, in particular, to a railroad collision avoidance system and method for preventing train accidents." It addresses a stated need for a system that "can effectively warn a person when there is a locomotive in their vicinity."
Plain-language scope (per the supplied text): The system and method "utilize impulse radio technology to effectively warn a person when there is a locomotive in their vicinity." A transmitting impulse radio unit is coupled to a locomotive and transmits an impulse radio signal toward a vehicle when the locomotive is a predetermined distance from a railroad crossing. A receiving impulse radio unit coupled to the vehicle ensures the person operating the vehicle "is informed about the potentially dangerous situation." The excerpt notes prior-art context: a railroad-crossing warning system using magnetic probes over a 40×40 foot area to detect stalled vehicles, and a system of wireless trackside devices feeding a two-sided LED display, both described as still subject to interference within an assigned frequency.
Source: https://patents.google.com/patent/US6759948/en (fetched 2026-09-24).
What the excerpt does not establish: It does not reproduce the full claims, detailed description, figures, or drawings (image content is not rendered). It does not establish claim scope, claim count, dependencies, or the specific technical details of the impulse radio implementation. It does not establish validity, enforceability, litigation history, ownership transfers, or the content of cited prior art beyond the brief background passages quoted. AU/PCT/continuation records and later patents referencing this one are listed but not explained here.
Generated 10/1/2026, 9:40:47 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.