US 9043131

I'll run targeted searches for this specific patent number and any related CAFC 2026 docket activity.

Let me pull the actual claim language and confirm the claim-dependence structure.

I have claim 1's element breakdown; let me get claim 17's full text and confirm the independent claims.

US Patent 9,043,131 — Analyst Summary

Scope note: All results below pertain exclusively to US 9,043,131 (the "’131 patent") and its directly associated proceedings. I did not substitute any similar-looking numbers.

Date discrepancy flag: You state the current date is April 26, 2026, but my searches returned material dated May 11, 2026 and later (a Federal Circuit opinion and mid-2026 district-court docket entries). My system date is 2026-09-11. I am reporting those later results as current ground truth, but you should be aware the "current date" inputs are inconsistent.

1. Bibliographic data

Sources: https://patents.google.com/patent/US9043131/en ; https://www.freepatentsonline.com/9043131.html ; https://uspto.report/patent/grant/9,043,131

One source (an IPR case page) labels the patent "Rail Vehicle Collision Avoidance System." That appears to be a shorthand description used in the IPR record, not the granted title. The granted title is as stated above.

2. Abstract (verbatim)

"A collision avoidance system (CAS) is described that includes one or more sensor technologies, including, for example, an Ultra Wideband (UWB) sensing technology. The collision avoidance system is designed to reliably track the location and speed of vehicles and the distance between vehicles over a wide variety of track and terrain. The collision avoidance system may utilize information from a variety of sensor technologies to determine whether one or more vehicles violate speed and/or separation criteria, and may generate a warning."

3. Claim-set structure

Confirmed from the PTAB Final Written Decision in IPR2023-00468:

• Claims 1 and 17 are the only independent claims.
• Claims 2–16 depend (directly or indirectly) from claim 1.
• Claims 18–20 depend from claim 17.

Source: https://ai-lab.exparte.com/documents/ptab/ptacts-uspto/[1550912](/patent/1550912)/.../IPR2023-00468_doc_71_exparte.pdf ("Claims 1 and 17 are independent. Claims 2–16 depend from claim 1. Claims 18–20 depend from claim 17.")

4. Plain-language overview of the independent claims

Claim 1 — System claim (two linked vehicle-mounted modules)

Element breakdown as quoted in the IPR record:

• [1-Pre/1A] A collision avoidance system comprising a first vehicle-mounted module mounted on a first rail vehicle.
• [1B] A first transponder sensor module operable to send/receive data wirelessly, comprising a first radio communication unit and a first antenna.
• [1C] A first control electronics module with a first processor in communication with at least the first transponder sensor module.
• [1D] A first user interface module with a user interface that provides rail-vehicle information to an operator and accepts operator input.
• [1E–1H] A mirror-image second vehicle-mounted module on a second rail vehicle, having its own transponder sensor module (radio unit + antenna), control electronics module (processor), and user interface module.
• [1I] The first vehicle-mounted module is operable to communicate with the second vehicle-mounted module.

Plain language: It is a two-vehicle (and by extension multi-vehicle) radio-based collision-avoidance architecture in which each rail vehicle carries a matched set of three subsystems — a wireless transponder/sensor unit, a processor-based control module, and an operator display/input unit — and the vehicle modules talk to each other. Supporting disclosure says the radio communication unit is realized as an Ultra Wideband (UWB) transponder and that the processor uses time-of-flight (TOF) ranging to derive separation distance; a warning is issued if separation criteria are violated.

Uncertainty: A later limitation in claim 1 is designated [1J] in the IPR record and is referenced as the limitation covering how separation distance "is determined from the impulse radio signal (via the time of flight technique)," and the claim as a whole is treated as including separation-criteria/warning functionality. I did not retrieve the verbatim text of [1J] and any elements after [1I], so I am not quoting them.

Claim 17 — Module claim (per-vehicle module; time-of-flight)

As quoted/paraphrased in the PTAB and Federal Circuit record:

• [17-Pre] "A rail vehicle module mountable on a first rail vehicle, the module comprising:"
• [17A] A transponder sensor module (wireless send/receive).
• [17B] "employ[s] time of flight techniques to detect a separation distance between the first rail vehicle and a second vehicle."
• [17C] "a first wireless communications antenna operable to send and receive data representing the separation distance over the air."
• [17G] "the rail vehicle module communicates with a second rail vehicle module mountable on the second vehicle to detect a separation distance between the first rail vehicle and the second vehicle."

Plain language: Claim 17 claims the single-vehicle hardware unit (rather than the whole two-vehicle system), and its distinguishing feature is that it expressly performs TOF ranging to find the separation distance and has an antenna that sends/receives "data representing the separation distance" over the air.

This claim limitation (17C) became the pivotal issue in the 2026 Federal Circuit appeal (see §5).

5. Post-grant and litigation status (this is where the ’131 patent's story now sits)

PTAB — IPR2023-00468 (and companion IPR2023-00470 for the ’227 patent)

• Petition filed Jan 13, 2023 by Siemens Mobility, Inc., Ground Transportation Systems USA, Inc., Humatics Corp., and Piper Networks, Inc.
• Challenged claims: 1–20
• Final Written Decision (2024): claims 1–16 unpatentable as obvious; claims 17–20 not shown unpatentable (Grisham, US 6,759,948, failed to disclose limitation 17C under the Board's construction).
• Sources: https://ai-lab.exparte.com/case/ptab/IPR2023-00468/doc/1001 ; https://services.patexia.com/lawsuits/shorturl-id-[185278](/patent/185278) ; https://portal.unifiedpatents.com/ptab/case/IPR2023-00468

CAFC — Metrom Rail, LLC v. Siemens Mobility, Inc., Nos. 24-2223, 24-2236, 24-2264

• Argued April 13, 2026; opinion issued May 11, 2026 (nonprecedential).
• Affirmed-in-part: all claims of the ’227 patent and claims 1–16 of the ’131 patent unpatentable as obvious (secondary-considerations/nexus argument rejected under Fox Factory v. SRAM; single-reference Grisham obviousness upheld).
• Reversed-in-part: the Board's holding that claims 17–20 survived. The panel held the Board misconstrued "data representing the separation distance" — it means the data used in the TOF calculation, not the computed distance — and Grisham discloses transmitting that data over the air. Result: claims 17–20 of the ’131 patent also unpatentable.
• Judge Taranto concurred-in-part and dissented-in-part, on party-presentation/preservation grounds (Siemens never advanced a claim-construction argument on the cross-appeal).
• Sources: https://cafc.uscourts.gov//opinions-orders/24-2223.OPINION.5-11-2026_2691571.pdf ; https://law.justia.com/cases/federal/appellate-courts/cafc/24-2223/24-2223-2026-05-11.html ; https://fedcircuitblog.com/2026/05/12/opinions-orders-may-12-2026/

District courts (all involving the ’131 patent per Google Patents / Unified Patents litigation data)

• D. Del. 1:22-cv-00049; 1:23-cv-00314
• S.D.N.Y. 1:23-cv-02920; 1:23-cv-03057; and 1:25-cv-10417 (Metrom Rail, LLC v. Massachusetts Bay Transportation Authority)
• D. Mass. 1:25-cv-11446
• In the MBTA case, Judge Denise L. Cote (S.D.N.Y.) denied Piper's preliminary-injunction motion without prejudice and stayed the case until the Federal Circuit's ’131 decision is final and the mandate issues; the ’131 claim was dismissed as moot, while the ’738 patent claim survived dismissal (Docket entries 112–117, May–Aug. 2026).
• Sources: https://patents.google.com/patent/US9043131/en ; https://www.courtlistener.com/docket/72043751/feed/

6. Bottom line

US 9,043,131 is Metrom Rail's foundational UWB + GPS rail-work-gang collision-avoidance patent, filed as a continuation of a May 19, 2011 priority family, granted May 26, 2015, with independent claims 1 (two-vehicle system) and 17 (per-vehicle TOF module). As of the May 11, 2026 Federal Circuit decision in Metrom Rail v. Siemens Mobility, every claim (1–20) has been held unpatentable as obvious, subject to any rehearing/en banc activity and issuance of the mandate — which the S.D.N.Y. court is expressly waiting on. Google Patents still displays a "Active" legal status, but that status field has not been updated to reflect the 2026 appellate outcome.

Explicit uncertainties:

1. I could not retrieve the verbatim text of claim 1's limitations after [1I] (including [1J]) or claim 17's limitations 17D–17F/17H onwards; treat those descriptions as reconstruction from the IPR and CAFC record, not quotation.
2. PTAB FWD dates in secondary sources differ (June 18, 2024 per Patexia vs. an August 26, 2024 date on one PTAB document); I have not verified the exact signature date.
3. Claim 17's title in some IPR-facing databases ("Rail Vehicle Collision Avoidance System") differs from the granted title — I treat the granted title as authoritative.
4. I did not independently verify the current assignee chain or any post-2023 assignments beyond the records cited.

I'll research the litigation history for US patent 9043131, starting with the sources you've identified.

I have substantial results. Let me pull details on the specific district court cases and the two Federal Circuit appeals.

Let me gather details on the remaining cases, including the 2023 New York actions and the second Federal Circuit appeal.

Litigation Involving U.S. Patent No. 9,043,131 (the "'131 patent")

Patent: U.S. 9,043,131 B2 — "Collision avoidance system for rail line vehicles"
Assignee/Patent Owner: Metrom Rail, LLC (Lakemoor, Illinois)
Priority date: May 19, 2011 | Granted: May 26, 2015 | Application: 14/252,987

Bottom line: Yes — there is a substantial, well-documented litigation and PTAB history. The '131 patent has been asserted in at least five U.S. district court actions (D. Del., S.D.N.Y., D. Mass.), challenged in at least one IPR, and is the subject of a Federal Circuit appeal decided May 11, 2026. All challenged claims of the '131 patent have now been held unpatentable, which has begun to moot the infringement side of the dispute.

1. District Court Litigation

(a) Metrom Rail, LLC v. Siemens Mobility, Inc. et al. — D. Del.

Sources: RPX Insight (https://insight.rpxcorp.com/litigation/dedce-77707-metrom-rail-v-siemens-mobility); CourtListener memorandum order (https://www.courtlistener.com/opinion/[9635981](/patent/9635981)/metrom-rail-llc-v-siemens-mobility-inc/)

(b) Metrom Rail, LLC v. Ground Transportation Systems USA Inc. et al. — D. Del.

Sources: Unified Patents litigation portal; GoldenCompass railroad patent litigation table (https://goldencompass.patentpia.com — litigation ID 127311)

(c) Metrom Rail, LLC v. Siemens Mobility, Inc. et al. — S.D.N.Y.

Sources: CourtListener docket; PTAB Exhibit 1019 (Second Amended Complaint, ECF 69-1); stay order hosted at ptacts.uspto.gov (petition 1556106)

(d) Metrom Rail, LLC v. Siemens Mobility, Inc. et al. — S.D.N.Y. (second NY action)

Source: Google Patents litigation links for US 9,043,131; GoldenCompass table (litigation ID 127451). This appears to be a companion action filed alongside 23-cv-03057.

(e) Metrom Rail, LLC v. Massachusetts Bay Transportation Authority et al. — D. Mass.

Sources: Finnegan, "D. Mass. Patent Litigation Update: December 2025" (http://www.finnegan.com/print/content/[433043](/patent/433043)/); Justia Dockets (https://dockets.justia.com/docket/new-york/nysdce/1:2025cv10417/[654853](/patent/654853))

(f) Metrom Rail, LLC v. Massachusetts Bay Transportation Authority et al. — S.D.N.Y. (transferred-in)

Sources: CourtListener docket 72043751 (https://www.courtlistener.com/docket/72043751/metrom-rail-llc-v-massachusetts-bay-transportation-authority/); PACER Monitor case 61864670 (note: PACER Monitor lists this as filed in S.D.N.Y.; the D. Mass. docket reflects a May 21, 2025 filing date)

2. PTAB Proceedings (Inter Partes Review)

IPR2023-00468 — Petitioners v. Metrom Rail, LLC (U.S. 9,043,131)

Sources: PTAB Final Written Decision, IPR2023-00468 Paper 71; CAFC opinion 24-2223; Ex Parte AI Lab docket (https://ai-lab.exparte.com/case/ptab/IPR2023-00468/siemens-mobility-inc-v-metrom-rail-llc)

Related PTAB matters (not on the '131 patent, but same family/campaign):

• IPR2023-00470 — parallel IPR on U.S. 8,812,227 ('227 patent); all claims held unpatentable; heard jointly with -00468.
• IPR2024-00947 — Siemens Mobility, Inc. v. Metrom Rail on U.S. 9,731,738 ('738 patent); institution denied November 20, 2024 (issues substantially the same as those already considered during prosecution). Panel: APJs Powell, White, Dougal.

Source: McAndrews IP press release, 11.21.24 (https://www.mcandrews-ip.com/mcandrews-secures-victory-for-client-metrom-rail-llc/)

3. Appellate Litigation

Metrom Rail, LLC v. Siemens Mobility, Inc. et al. — U.S. Court of Appeals for the Federal Circuit

Sources: CAFC opinion 24-2223 (https://cafc.uscourts.gov/opinions-orders/24-2223.OPINION.5-11-2026_2691571.pdf); Fed Circuit Blog (https://fedcircuitblog.com/2026/05/12/opinions-orders-may-12-2026/); VitalLaw IP Law Daily (May 12, 2026); CourtListener opinion 10856969

Appeal key holdings of interest:

• Nexus / secondary considerations: Under Fox Factory, Inc. v. SRAM, LLC, 944 F.3d 1366 (Fed. Cir. 2019), Metrom was not entitled to a presumption of nexus between its AURA CAS product and the claims, because AURA CAS had important unclaimed features (machine-function monitoring and remote data reporting). Metrom also failed to show commercial success was the "direct result of the unique characteristics of the invention."
• Single-reference obviousness: Claim 1 of each patent was obvious over Grisham alone.

4. Caveats and Unverified Leads

1. Case number discrepancy for the Federal Circuit appeal. Google Patents lists two FC case numbers for this patent family: 24-2223 and 24-2264. My search for 24-2264 did not return confirming results, and RPX separately lists a 24-2236 (Metrom Rail, LLC v. Siemens Mobility, Inc., filed 08/19/2024). The published opinion issued under 24-2223; I cannot confirm the disposition of 24-2264 or 24-2236, and I will not assume they are the same docket.
2. 1:23-cv-02920 (S.D.N.Y.) — confirmed to exist on the Google Patents litigation link list for the '131 patent, but I could not verify parties, filing date, or outcome.
3. 1:23-cv-00314 (D. Del.) — confirmed filing, parties, and patents; disposition unconfirmed.
4. Possible additional S.D.N.Y. action. A Unified Patents patent page surfaced a S.D.N.Y. case, 1:23-cv-00581 (Metrom Rail LLC v. Siemens Mobility GmbH, Piper Networks Inc., Ground Transportation Systems USA Inc.), but the page was captioned for a different patent number ("US-9595-A"). Unverified that this case involves the '131 patent — do not rely on it without a PACER check.
5. Third Circuit attribution. One aggregator (Studicata) summarizes the D. Del. severance/dismissal order under the heading "United States Court of Appeals, Third Circuit (2023)." That is almost certainly a database mislabel of the district court's Memorandum Order in 22-cv-00049-RGA, not a Third Circuit appeal.
6. Date inconsistency. The search results include events dated May and June 2026 (CAFC decision May 11, 2026; S.D.N.Y. orders May 20 and June 4, 2026), which post-date the April 26, 2026 date given in your prompt. I have reported them as found, since the instruction is to treat search results as the current ground truth.
7. Trial-level details. I did not retrieve a final judgment, damages award, or settlement agreement in any of the district court actions, and I could not review PACER directly. Findings/outcomes in the district court cases (other than those quoted above) should be confirmed against PACER.

5. Practical Takeaway for the '131 Patent

The '131 patent is now, on the PTAB/FC record, fully invalidated: independent claim 1 fell under IPR2023-00468 (affirmed), and claims 17–20 — the only surviving claims — were held unpatentable on cross-appeal on May 11, 2026. This is already flowing through to the co-pending S.D.N.Y. case (1:25-cv-10417), where the '131 claim was dismissed as moot and the case was stayed pending finality of the Federal Circuit mandate. The related '738 patent (U.S. 9,731,738) remains the live patent in that dispute, and its IPR (IPR2024-00947) was denied institution.

I'll research the PTAB proceedings. The structured ODP block says "no proceedings," but the patent text itself references IPR2023-00468 — so I need to verify that via web search and reconcile the conflict.

I'm finding a real IPR (IPR2023-00468) despite the ODP block saying "none." Let me pull the FWD claim-level details, the panel, and the appeal record.

Let me confirm the appeal-number mapping and whether any other IPR targets the '131 patent.

⚠️ Source conflict — flagged. The structured "PTAB proceedings on file" block says USPTO ODP returns no AIA trial proceedings for US 9043131 and instructs me to default to "no PTAB activity." That default is wrong here. Web sources — including the patent's own Google Patents page, the PTAB docket, the PTAB Final Written Decision, and a published Federal Circuit opinion — establish a full IPR on this patent that ran to a Final Written Decision and was appealed. The ODP ingest for this patent is stale/incomplete. Per the operating rules ("when live web search results contradict [the default], prefer the search results"), I report the real proceeding below and treat the ODP "none" as an ingestion gap.

Proceedings overview

One AIA trial proceeding has been filed against US 9043131 — IPR2023-00468 (status: Final Written Decision – Appealed; PTAB outcome: Unpatentable). At the PTAB, claims 1–16 were held unpatentable and claims 17–20 were sustained; on appeal the Federal Circuit affirmed as to claims 1–16 and reversed as to claims 17–20, holding those also unpatentable — meaning every claim (1–20) of the '131 patent now stands adjudicated invalid. Bottom-line defensive posture for a defendant: the patent is effectively dead. There are no surviving claims, no active proceeding to "wait out," and no live claim to design around. Any demand letter or complaint asserting US 9043131 — including one citing claims 17–20, which a patent owner might have hoped survived — is built on claims a Federal Circuit panel held obvious over Grisham et al.

IPR2023-00468 — Siemens Mobility, Inc., Ground Transportation Systems USA, Inc., Humatics Corp., and Piper Networks, Inc. v. Metrom Rail, LLC

• Type: Inter Partes Review (35 U.S.C. §§ 311–319)
• Filed: 2023-01-13 (accorded filing date)
• Status: Final Written Decision – Appealed (structural data). Plain-English gloss: trial completed, all challenged claims adjudicated, and the appeal (main + cross-appeal) has now been decided by the Federal Circuit.
• Judge panel: Neil T. Powell, Stacey G. White, and Iftikhar Ahmed, Administrative Patent Judges; Judges Powell and White authored the Decision, Judge Ahmed authored the Final Written Decision (the FWD caption lists these three). ⚠️ Note: some third-party docket aggregators (Patexia, Docket Alarm) also list Hyun J. Jung and James P. Calve in connection with this docket number; those names appear to be associated with the parallel '227 proceeding (IPR2023-00470). I treat the FWD caption — Powell, White, Ahmed — as authoritative for the '131 FWD.
• Petition grounds (challenged claims 1–20; all grounds are § 103 obviousness, no § 102 or § 112 grounds):
  • Ground 1 — claims 1, 11, 14 obvious over Grisham (U.S. Patent No. 6,759,948). Grisham (railroad collision-avoidance using UWB impulse radios / time-of-flight) was the primary reference and was not before the examiner during prosecution.
  • Ground 2 — claims 7–9, 17, 19 obvious over Grisham in view of Nixon (Int'l Pub. No. WO 03/009254 A1) for GPS absolute-position and progressive-warning limitations.
  • Ground 3 — claims 1, 7–8, 11–14, 17 obvious over Suzuki (EP 1 785 744, automotive UWB radar with GPS) alone or in view of Grisham.
  • Additional combinations: Grisham + Nixon + Richardson (claimed 18) and Grisham + Nixon + Richardson + Douglas (U.S. Patent No. 8,874,359) (claim 20) — these were the subject of the cross-appeal.
• Institution decision: Instituted, 2023-06-23 (institution granted on the then-pending claims). The Board adopted Petitioner's proposed level of ordinary skill ("background in wireless electronics… at least two years of experience… with control systems such as collision-avoidance or positioning systems") and rejected Patent Owner's attempt to narrow the relevant art to railway systems. A trial hearing was held 2024-03-28.
• Final Written Decision: issued 2024-06-18, captioned "Final Written Decision Determining Some Challenged Claims Unpatentable." Verdict at claim level:
  • Claims 1–16 — UNPATENTABLE. Independent claim 1, plus dependents 2–16 (the FWD notes "Claims 2–16 depend from claim 1").
  • Claims 17–20 — NOT unpatentable. Independent claim 17 and dependents 18–20 survived at the PTAB because the Board found Grisham did not disclose limitation 17C, "a first wireless communications antenna operable to send and receive data representing the separation distance over the air." The Board reasoned that Grisham's time-of-flight relies only on signal timing, not on data encoded with the computed separation distance, and that a locomotive able to compute distance need not transmit it.
  • The Board also rejected Metrom's secondary-considerations evidence (AURA CAS product): no presumption of nexus where the commercial product had "important unclaimed features" (machine-function monitoring, remote data reporting) that were "not insignificant."
• Settlement / termination: None. This proceeding ran to a contested FWD; there was no adverse-judgment or settlement termination on the record.
• Appeal: Yes. Metrom appealed the unpatentability findings; Petitioners cross-appealed the claims 17–20 ruling (cross-appeal filed 2024-08-26). The appeals were consolidated as 24-2223 (lead), 24-2264 (cross-appeal), and 24-2236 (the '227 companion). Arguments were heard 2026-04-13. Decision issued 2026-05-11 (nonprecedential): AFFIRMED-IN-PART AND REVERSED-IN-PART.
  • Affirmed: all claims of the '227 patent and claims 1–16 of the '131 patent unpatentable — secondary-considerations/nexus and single-reference obviousness arguments rejected.
  • Reversed: claims 17–20 of the '131 patent held unpatentable. The court held the Board misconstrued "data representing the separation distance," reasoning that "the Board's critical error was agreeing with the theory… that the claim term 'data representing the separation distance' means only the computed separation distance rather than data that is then used in the time-of-flight calculation." Because Metrom itself had told the district court that term means "data used to determine the time of flight," the court found no dispute that Grisham satisfies 17C: "we conclude that petitioners have shown that claims 17–20 of the '131 patent are unpatentable as obvious. We reverse with respect to petitioners' cross-appeal."
  • Dissent: Judge Taranto concurred-in-part and dissented-in-part, arguing the majority improperly decided the cross-appeal on its own claim construction that Siemens never presented "in this court" or "before the Board." ⚠️ This is a live vulnerability if any further review is sought — but as of today it is a dissent, not the holding.
  • Costs awarded to appellees/cross-appellants.
• Defensive value: Claim 1 and all of claims 2–16 are dead (PTAB, affirmed) — any infringement theory built on them is unsupportable. Claims 17–20 are also dead (Federal Circuit reversal, 2026-05-11). There is no claim of US 9043131 left standing on the current record. A defendant should treat this as a complete invalidity defense with a fully developed, judicially blessed record.

Primary sources: PTAB E2E case record — https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550912](/patent/1550912) · FWD (2024-06-18) and related papers · Federal Circuit opinion, No. 24-2223 (2026-05-11) — https://cafc.uscourts.gov//opinions-orders/24-2223.OPINION.5-11-2026_2691571.pdf · CourtListener — https://www.courtlistener.com/opinion/[10856969](/patent/10856969)/metrom-rail-llc-v-siemens-mobility-inc/ · Justia — https://law.justia.com/cases/federal/appellate-courts/cafc/24-2223/24-2223-2026-05-11.html

Strategic summary

Claim status of US 9043131. On the current record, all 20 claims are invalid: claims 1–16 were held unpatentable by the Board (FWD 2024-06-18) and that holding was affirmed; claims 17–20 were initially sustained by the Board but were reversed and held unpatentable by the Federal Circuit (2026-05-11). There are no "surviving claims" and no "untested claims" — the petition challenged the full claim set 1–20. (Caveat: the Board's unpatentability findings do not self-execute as cancellation of the patent; the claims are canceled only upon issuance of a certificate after the appeal is final. As of 2026-09-11, the appeal opinion is dated 2026-05-11 and no further appellate activity has surfaced in my sources — treat the claims as adjudicated invalid, subject to the formal certificate and the residual possibility of rehearing/certiorari.)

Estoppel landscape. Because IPR2023-00468 ran to a Final Written Decision, § 315(e)(2) estoppel attaches to Petitioners Siemens Mobility, Ground Transportation Systems USA/Hitachi Rail GTS USA, Humatics, and Piper Networks (and their real parties-in-interest and privies): they are barred in the parallel district-court actions from asserting invalidity grounds they raised or reasonably could have raised — including Grisham, Nixon, Suzuki, and the Grisham/Nixon/Richardson/Douglas combinations. For a different defendant being asserted today, estoppel does not apply, but it is largely academic: the patent is invalid as adjudicated, so a new defendant's cheapest move is to rely on the already-issued invalidity judgment (issue preclusion / stare decisis on the same claims and same art) rather than re-litigate. Any prior art beyond Grisham/Nixon/Suzuki/Richardson/Douglas remains unadjudicated and technically available, but is unnecessary.

Pattern signals. (1) No defensive aggregator. The Patent Owner's Google Patents page surfaces "Unified Patents" only as the data-provider attribution for the PTAB entry — Unified Patents is not a petitioner here. The real petitioners are industry competitors (Siemens Mobility, Hitachi Rail GTS USA f/k/a Ground Transportation Systems USA, Humatics Corp., Piper Networks) defending themselves against Metrom Rail's infringement campaign. (2) Metrom is an active serial litigant, not a passive patent owner: it sued across D. Del. (1:22-cv-00049, 1:23-cv-00314), S.D.N.Y. (1:23-cv-02920, 1:23-cv-03057, 1:25-cv-10417), and D. Mass. (1:25-cv-11446), and pursued the PTAB losses up through the Federal Circuit. (3) Same petitioner group filed multiple IPRs across the Metrom family — the FWD references IPR2023-00439, -00452, -00460, and -00468 as involving the same parties (with -00470 covering the sibling '227 patent). (4) The patent owner fought hard on secondary considerations (AURA CAS, skepticism, commercial success) and lost on nexus at both the Board and the Federal Circuit — so expect no non-obviousness rebound from that record.

Recommended next steps

• If you are a defendant: certify a copy of the FWD (2024-06-18) and the Federal Circuit opinion (24-2223, 2026-05-11) into the case. The dispositive language is: "we conclude that petitioners have shown that claims 17–20 of the '131 patent are unpatentable as obvious. We reverse with respect to petitioners' cross-appeal" (Federal Circuit) plus the FWD's "claims 1–16 are unpatentable." Together these cover all of claims 1–20.
• Watch the formal cancellation: confirm whether the mandate has issued from the Federal Circuit and whether a petition for rehearing/rehearing en banc (FRAP 40, ordinarily due ~30 days after judgment) or a certiorari petition was filed. The Taranto dissent — that the majority decided the s17–20 cross-appeal on a construction Siemens never presented — is the only plausible avenue to disturb the claims 17–20 holding, so it is worth monitoring. If no further review, the '131 claims will be canceled by certificate and the patent is a nullity.
• No active PTAB trial to track: there is no pending IPR/PGR/CBM on this patent. The "1-year-from-institution FWD" clock is irrelevant here; the matter is at the appellate/post-appeal stage, not trial stage.
• Do not rely on the ODP "no proceedings" signal. The absence of ODP records for this patent is a data-ingestion artifact, not evidence of a clean patent. If you build a docket-monitoring workflow on ODP alone, this patent is exactly the failure mode that will burn you — corroborate against PTAB E2E and the Federal Circuit docket.
• If you are the patent owner: the '131 patent is your weakest asset after this appeal. Any new assertion should pivot to unadjudicated sibling patents in the Metrom family (e.g., the '227 patent was also invalidated — see IPR2023-00470 — so screen the rest of the portfolio for claims outside the Grisham/Nixon/Suzuki art set before filing).

Verification note: proceeding number, parties, filing/institution/FWD dates, panel, grounds, and the Federal Circuit disposition are drawn from the PTAB FWD, the CAFC opinion (No. 24-2223, 2026-05-11), and the PTAB/CAFC dockets. I have not independently verified the FWD's internal page cites or the exact dates of the appeal briefs; the Taranto dissent's framing is quoted from the published opinion summary.

I'll research the assignment records for US 9,043,131 across the sources you specified.

Let me dig into the actual assignment records and entity history.

⚠️ Retrieval limitation — read first

I was unable to retrieve the USPTO Assignment Center abstract of title for US 9,043,131 in this session. Direct queries against assignmentcenter.uspto.gov / assignment.uspto.gov and third-party mirrors did not return reel/frame-level data for this patent. I therefore have no verified reel/frame numbers, execution dates, or correspondents to report, and I will not invent them.

What I can report is negative evidence from sources that do index assignment activity: the Google Patents legal-events list for this patent shows only application filing (2014-04-15), priority claim, pre-grant publication (2014-08-14), grant (2015-05-26), status, and anticipated expiration — no "Assigned to" event appears in that timeline. The pre-grant publication and the granted patent both name Metrom Rail, LLC as applicant/assignee with no intervening assignee. That is consistent with (but does not prove) the absence of any post-issuance recorded transfer.

Treat every reel/frame field below as unfilled rather than as "none of record." A manual search is required to close this out.

Inventors

Employer determination: Metrom Rail, LLC was founded in 2010 in Crystal Lake, IL by Jim Marchi and Rick Carlson Sr. — roughly one year before this patent's 2011-05-19 priority date. All three named inventors are within commuting distance of the Crystal Lake/Lakemoor facility, and the same three names recur as inventors on Metrom Rail's later patents.

Unusual-pattern check — result: NO departure pattern.

• The three inventors did not leave within 12 months of filing. The opposite: they co-invented together on Metrom Rail's subsequent filings for ~15 years — US 9,731,738 (2017), US 10,778,363 (2020), US 10,737,709 (2020), US 11,349,589 (2022), and US 12,258,058 (issued 2025-03-25), the last still naming Carlson, Gunther, and Cygnus with Illinois residences.
• This is a founder-and-lifer team inside a small single-site manufacturer, not a research team that abandoned an assignee before a portfolio fire-sale.

Note: This patent traces to a 2011 priority family (also including WO 2012/158906 A1 and pre-grant pub. US 2014/0229096 A1). One family member, US 8,812,227 ("the '227 patent"), is a sibling with a common specification — relevant to the joint invalidation outcome described in the previously generated section.

Original assignee

• Entity named on the issued patent: Metrom Rail, LLC (original assignee and, per the sources reviewed, still the assignee of record).
• Address on record: 1125 Mitchell Court, Crystal Lake, IL 60014 (2010–~2019 patents); filings from 2025 (US 12,258,058) list Lakemoor, IL — a change of address, and I cannot confirm whether a change-of-address/change-of-name filing was separately recorded at the USPTO. Flag as unresolved.
• Primary line of business: railroad safety and control systems — ultra-wideband (UWB) radio-based train control, collision avoidance, and worker protection systems. Product families include the AURA line (AURA PTC, collision avoidance, worker protection).
• Did they ship a product embodying the claims? Yes. Metrom Rail "develops, builds and integrates technology products for transit and freight organizations," designs/assembles/tests its complete product line at its Crystal Lake headquarters, and was described in 2018 as a ~40-person company that is "the only company on earth to provide ultra-wideband-based train control systems." It won the NY MTA Genius Transit Challenge in March 2018 for its PTCS-2 UWB train-control submission (1 of 438 entries). The '131 disclosure's own vocabulary — VMM, TSM, CEM, UIM, CTU, ground-speed sensors, work-gang separation thresholds — maps directly onto shipped AURA hardware.
• Current status: Operating as a privately held company. It is an active litigation plaintiff as recently as 2025–2026, which confirms it has not dissolved. No bankruptcy, no Chapter 7/11 proceeding, and no acquisition surfaced in my searches. It is not SEC-reporting (no 10-K/8-K trail), so ownership cannot be corroborated through SEC filings.

Assignment timeline

Plainly stated: I could not retrieve any recorded assignment entries for US 9,043,131, so I cannot present a reel/frame chronology. Because the USPTO Assignment Center data did not load, the honest position is:

• Inventor → Metrom Rail assignment (expected but unverified). As an employer-owned patent with a company as applicant on the 2014 pre-grant publication, there must be (or be relied-upon employment agreements in lieu of) an inventor-to-company assignment chain. I did not retrieve it, and I am not asserting a reel/frame for it.
• Post-issuance transfers: none surfaced. Google Patents' legal-events list for this patent reflects no assignment event after grant, and no secondary source (FreePatentsOnline, uspto.report, RPX, Unified Patents, Patexia, PatentPia) describes a transfer of this patent to any third party. The Unified Patents and PatentPia records list Metrom Rail, LLC as the patent's current owner throughout the 2023–2026 IPR and appeal proceedings.

Per your instruction, I am flagging this plainly rather than constructing a chain: I do not have records to fill in the "YYYY-MM-DD / recorded / Reel NNNNNN/NNNN / Conveyance / Assignor / Assignee / Correspondent" fields. I will not populate them by inference. The actionable next step is a name search in the Assignment Center for assignor "Carlson, Richard C." and assignee "Metrom Rail LLC" — that will surface the inventor assignments (if any) and any subsequent conveyances in one query.

Timeline diagram

Rendered from the historically verified events (ownership events, since no ownership transfers are documented). No parentheticals, slashes, or commas.

timeline
    title Ownership of US 9043131
    2011 : Priority application filed by Metrom Rail
    2014 : Continuation filed by Metrom Rail
    2015 : Patent issued to Metrom Rail LLC
    2022 : Metrom Rail sues Siemens and others
    2023 : IPRs filed by Siemens and others
    2024 : PTAB invalidates claims 1 through 16
    2026 : Federal Circuit invalidates all claims

NPE / troll-pattern signals

Assessed against the enumerated eight signals. No signal is marked "present" — the evidence runs the other way.

Additional observation worth recording (not a numbered signal)

The assertion campaign has two faces worth distinguishing. The 2022–2023 suits target direct competitors. But later dockets — S.D.N.Y. 1:25-cv-10417 (Metrom Rail, LLC v. Massachusetts Bay Transportation Authority) and D. Mass. 1:25-cv-11446 — appear to involve a transit agency as defendant, i.e., a potential end-user/customer rather than a competing vendor. Suing one's own downstream market is the one behavioral marker here that rhymes with NPE conduct. I flag it as unclear: I have not verified the accused products, the license history with MBTA, or whether MBTA was previously a Metrom Rail customer. Given the constraints you set, "could be an end-user suit" is not a finding.

Verdict

Operating-company assertion

Justification: Metrom Rail, LLC is a bona fide operating manufacturer — it designs, builds, and tests UWB rail-safety hardware (AURA PTC, collision avoidance, worker protection) at 1125 Mitchell Court, Crystal Lake, IL, employs roughly 40 people, won the NY MTA Genius Transit Challenge in 2018, and is both the original and apparent current assignee of US 9,043,131. It asserts the '131 patent in its own name against genuine competitors (Siemens Mobility, Thales, Hitachi Rail GTS, Humatics, Piper Networks) beginning 2022-01-13 in D. Del. 1:22-cv-00049 — with no assignment of record to any licensing entity and no NPE-list, bankruptcy, cascading-transfer, or defensive-aggregation marker present; six of the eight NPE signals are affirmatively not present and one (repeat correspondent) is simply unrecoverable.

Two material caveats that post-date the original analysis:

1. Per the previously generated section (which I am not repeating), the Federal Circuit's 2026-05-11 nonprecedential decision in Metrom Rail v. Siemens Mobility, Nos. 24-2223 et al., held all claims 1–20 unpatentable as obvious — including reversing the Board on claims 17–20. The assertion value of this asset is therefore effectively extinguished, pending rehearing/en banc and mandate. The S.D.N.Y. court is expressly staying the MBTA case on that mandate.
2. The verdict above is unchanged by that outcome. "Operating-company assertion" is a finding about who asserted and why, not about who won.

Verification link: https://assignmentcenter.uspto.gov/ — search by patent number 9043131 (also indexed at https://assignment.uspto.gov/patent/index.html). This search is the open item in this analysis: it is the only way to obtain the reel/frame entries, execution dates, and the correspondent of record that signal #3 requires, and it is the only way to confirm my negative finding that no post-issuance transfer exists.

I'll research the actual cited references on the face of US 9,043,131 (and its USPTO file record), then assess each for § 102 potential.

Let me pull the actual "References Cited"/"Patent Citations" lists from the USPTO/FPO records.

The Google Patents pages are truncating. Let me target the citation lists directly.

Prior-Art Analysis — US 9,043,131 B2 ("Collision avoidance system for rail line vehicles")

Scope guard: Everything below is keyed to US 9,043,131 and its own family/record. I did not substitute look-alike numbers.

1. Sourcing caveat (read first)

You asked me to walk each patent citation on the face of 9,043,131. I was unable to retrieve the verbatim "References Cited / Patent Citations" list from the front page. The Google Patents page for this patent renders its citation blocks via JavaScript, and every attempt returned truncated text (keyword-weighting tables, patent/US9043131B2/en labels, etc.) rather than the citation list itself. My step budget expired before I could pull the FPO/Patentpia/USPTO-PatentCenter front-page lists.

So this section is built on the documented prior-art record — the references actually asserted and adjudicated in IPR2023-00468 and on the Federal Circuit appeal (24-2223) — plus family-member cross-citations. That is, in practice, the more consequential prior art for this patent than the examiner-cited front page. I am explicitly flagging that the examiner/face-of-patent citation list is not reproduced here and should be confirmed against the patent's PDF or USPTO PatentCenter if you need the literal front-page set.

Governing law: The '131 claims the 2011-05-19 priority of app. 13/474,428 (pub. US 2012/0296562 A1) via continuation 14/252,987. Its effective filing date precedes 2013-03-16, so pre-AIA 35 U.S.C. §§ 102(a)/(b)/(e) apply — not the AIA §§ 102(a)(1)/(a)(2) scheme. This matters: § 102(b) requires publication/patenting more than one year before the earliest filing date in the benefit chain, i.e. a critical date of approximately 2010-05-19.

§ 102 framework: Anticipation requires a single reference disclosing every claimed element, arranged as in the claim. On this record, no reference was held to anticipate any claim — every adjudicated holding was § 103 (obviousness). That is itself the headline § 102 finding.

2. Reference-by-reference analysis

Group A — References actually litigated in IPR2023-00468 (the operative prior art)

Group B — Family references appearing in the patent-record cross-citations

I also encountered a citing document (CN 103298679 B, an ultra-wideband railway positioning/control reference) that lists the '131 and its WO counterpart in its own citation tables. That is subsequent art citing the '131 (i.e., "cited by," not "cited"), so it is not prior art against the '131 and I have not treated it as such.

3. Bottom line on § 102

1. No reference in the documented record anticipates any claim of the '131. Every adjudicated holding is § 103 — including the single-reference finding that claim 1 is obvious over Grisham alone, which by construction means Grisham did not disclose every limitation.
2. The strongest § 102(b) anticipation candidates are, in order: Grisham (US 6,759,948) against claim 1, and Suzuki (EP 1 785 744) against claims 1, 11–14, and 17 — Suzuki being attractive for § 102 because it packs UWB + GPS + TOF + display into one document. Both fail on the "rail vehicle" limitation (Suzuki plainly) or on one or more remaining elements (Grisham), which is why the case was won on § 103.
3. Nixon, McDaniel, Breed, and Connell are clean § 102(b) references (all published well before ~2010-05-19) but are each directed to only one claimed feature, so they support § 103 combinations rather than anticipation of any independent claim.
4. Douglas (US 8,874,359) is the weak link of the set — its 2014 grant date puts it outside § 102(a)/(b); its validity as art depends on an unverified pre-2011-05-19 filing date for § 102(e).
5. This § 102 picture is fully consistent with the previously generated sections: claims 1–16 fell in IPR2023-00468 and 17–20 were reversed into unpatentability on appeal (2026-05-11) — both on obviousness, not anticipation.

4. Explicit uncertainties

1. The face-of-patent "References Cited" list is not reproduced here — I could not retrieve it; the prior art above is drawn from the IPR/CAFC record and family cross-citations. Confirm the literal examiner-cited set via the granted PDF or PatentCenter.
2. Exact claim-number mapping of the secondary references (Douglas→CTU, McDaniel→adaptive threshold, Breed→IMU, Connell→stopping distance, Richardson→UWB offset) is reconstructed from the IPR grounds summary and the specification's feature list. Claim 1 and claim 17 are the only independents, and claims 2–16/18–20 are dependents, so the mapping is directionally reliable but should be verified against the claim set.
3. Grisham's exact grant date (2004-07-06) and Richardson's 2010 publication details are from memory/unverified — treat as approximate.
4. Douglas's filing date (and thus its § 102(e) eligibility) is unverified.
5. My searches for the appeal docket surfaced three Federal Circuit numbers (24-2223, 24-2236, 24-2264); the published opinion issued under 24-2223 — the others remain unconfirmed and are not assumed identical.

I'll ground this obviousness analysis in the actual prior-art record for the ’131 patent — the references the PTAB and Federal Circuit relied on in IPR2023‑00468 — plus the patent's own specification, which is the authoritative text supplied above.

Let me pull the remaining prior-art references and the full dependent-claim structure to complete the mapping.

Obviousness Analysis Under 35 U.S.C. § 103 — U.S. Patent No. 9,043,131

Date-of-record caveat (carried forward): You give the current date as April 26, 2026, but the record I am working from contains material dated through mid-2026 (the May 11, 2026 Federal Circuit opinion in Metrom Rail, LLC v. Siemens Mobility, Inc., Nos. 24-2223 et al., and a June 2026 combined petition for rehearing). My system date is 2026-09-11. I treat the later material as ground truth per the operating rules and flag the inconsistency rather than resolving it. This matters for § 103 because the legal validity determination has, as of that record, already been made — see § G below.

Method note: Per your instruction I am using the prior-art record actually developed against this patent — the references relied on in IPR2023-00468 and carried into the CAFC appeal. I am not substituting my own reference choices, and I am not quoting claim text I did not retrieve (see caveats in § H).

A. Legal framework and the level of ordinary skill

The § 103 inquiry here follows Graham v. John Deere Co., 383 U.S. 1 (1966): (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) the level of ordinary skill; and (4) secondary considerations. Because the ’131 patent has a May 19, 2011 priority date, the prior art must predate that date (Grisham, issued July 6, 2004; Nixon, published January 30, 2003; Suzuki, published May 16, 2007; Richardson, 2010 — all comfortably before it).

The Board adopted, and the Federal Circuit did not disturb, a POSITA definition of:

"a background in wireless electronics, including at least a bachelor's degree in electrical engineering or a related field, and … at least two years of experience with using such electronics for control systems applications such as collision-avoidance systems or positioning systems." (Paper 10 at 11, as quoted in Petitioners' Oral Argument Demonstratives.)

That is a modest skill level, and it is the single most important lever in this analysis: a POSITA at this level, working in a field where the problem (rail vehicles colliding in work gangs, and radar/GPS false alarms) was well known, is exactly the artisan KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), anticipated — one who combines known elements "according to known methods" to yield "predictable results." KSR at 401.

The patent's own specification supplies the stated problem for the § 103 "motivation" analysis, and it does so in the patentee's own words:

• Single-sensor (GPS or radar) systems fail in "blackout" areas — "around buildings, in the mountains, canyons, around sharp curves or in tunnels" (’131 specification, Background).
• Radar "may initiate numerous false positives … With the normal clutter of maintenance operations (people, equipment, trains on adjacent tracks, trackside structures, trestle sides, tunnel walls), radar-based sensors can become confused…"
• The stated solution is a "combination of sensor technologies, including an Ultra Wideband (UWB) sensing technology … to counter the limitations of previous systems."

That background section is, functionally, an admission of the problem to be solved — and under KSR at 420, "[a]ny need or problem known in the field of endeavor at the time of invention and addressed by the patent can provide a reason for combining the elements in the manner claimed."

B. The claims to be analyzed

As confirmed in the Board's Final Written Decision (Paper 71):

• Claims 1 and 17 are the only independent claims.
• Claims 2–16 depend from claim 1.
• Claims 18–20 depend from claim 17.

Claim 1 (system) requires first and second vehicle-mounted modules, each comprising (i) a transponder sensor module with a radio communication unit and antenna, (ii) a control electronics module with a processor, and (iii) a user interface module providing rail-vehicle information to an operator and receiving operator input; the modules are operable to communicate with each other; and the record identifies a further limitation (designated [1J]) in which each module applies a time-of-flight technique to determine a separation distance between the rail vehicles.

Claim 17 (single-vehicle module) requires a transponder sensor module that "employ[s] time of flight techniques to detect a separation distance," a wireless communications antenna "operable to send and receive data representing the separation distance over the air" (limitation 17C), and communication with a second rail vehicle module to detect the separation distance (17G).

Because each independent claim is a combination of individually known subsystems (radio ranging unit + processor + operator display + inter-vehicle link + TOF ranging), this is a classic KSR "combination of familiar elements" case rather than a case turning on a novel physical principle.

C. The prior art of record and what each reference teaches

Field-of-invention note: Suzuki and Richardson are automotive/industrial UWB references, not rail references. That is not an obstacle — Grisham itself is rail-based UWB, and KSR at 417 holds that "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious." The Board made exactly this finding for the Richardson combination.

D. The obviousness grounds, and why the artisan would combine

Ground 1A — Grisham alone renders claims 1, 11, and 14 obvious

This is the single-reference ground and the most important one, because the Federal Circuit affirmed it ("claim 1 of each patent was obvious over Grisham alone"; Metrom "did not challenge petitioners' contentions regarding the obviousness of these claims over Grisham" apart from secondary considerations).

Element mapping:

Why obvious: Grisham is not merely analogous art — it is the same art (railroad collision avoidance), solving the same problem, with every claimed subsystem in a single reference. Where a single reference discloses all elements, no "motivation to combine" is even needed; the question collapses to whether the reference's arrangement would have suggested the claimed arrangement, which it plainly does. The only substantive dispute was the meaning of TOF, and the Board credited the unrefuted expert testimony (Mr. Andrews) that "waveforms … in or near the noise floor" and the resulting "time position measurement" is a TOF calculation, reinforced by Grisham's incorporation of Richards.

Ground 1B — Grisham + Douglas → central tracking unit limitations

Douglas supplies central-tracking-unit functionality. Motivation: a work gang of "four to forty vehicles" (’131 specification) cannot practically be monitored by pairwise links alone; a POSITA seeking a fleet-level picture would add centralized tracking. When the claim recites a known data-aggregation function, combining it with a known ranging system is the "predictable use of prior art elements according to their established functions" that KSR at 417 makes obvious. The Board adopted Petitioner's arguments where the patent owner did not specifically rebut.

Ground 1C — Grisham + Richardson → multiple/offset transponder sensor modules (claims 5, 6)

Richardson teaches placing four UWB coordinate radios at the corners of a vehicle and selecting requester/responder pairs to minimize dilution of precision. The Board found the motivation persuasive and applied KSR at 417 verbatim:

"if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious."

The Board expressly credited Petitioner's point that "Richardson's multiple transponder sensor module (TSM) format can account for lengthy trains to prevent collisions at the train's front and rear," and that "UWB signal range is irrelevant in this scenario because the train would be within UWB range in the front via the front TSMs and in the rear via the rear TSMs." It found "a high degree of predictability in this art to support a reasonable expectation of success." This directly anticipates the ’131 patent's own disclosure (FIG. 9, discussion of two TSMs at the extreme ends to improve distance-measurement accuracy and calibration).

Ground 1D — Grisham + McDaniel → adaptive threshold feature (claim 10)

McDaniel "discloses a collision avoidance system that determines threshold warning distances and minimum distances to avoid collisions adaptively based on the velocities of vehicles." Motivation accepted: in a yard where trains legitimately sit "within feet of each other," a system that alarms on mere proximity is useless; a POSITA "would have understood that a collision-avoidance system would need a way of alerting an operator only to potential collision situations—not merely situations where a train is nearby." The Board rejected the patent owner's "absolute speed" argument, holding that the claim "simply recites 'speed,' not absolute speed."

Contradiction flag: The Board's opinion contains a passing statement that it was "not persuaded … that Grisham teaches measurement of absolute speed," while also stating that "Grisham already collects speed and distance data" and that Grisham teaches measuring speed "relative to the ground." These statements are in tension in the record as I retrieved it; the outcome did not turn on it because the claim does not require absolute speed.

Ground 1E/1F and 2B — Grisham + Connell (+ Nixon, McDaniel) → claims 15 and 16

Connell supplies the progressive-warning/stopping-distance-type feature. Claims 15–16 additionally require that the progressive warning increase in "signal rate, signal frequency, signal prominence, signal volume, or signal severity," and that an adaptive threshold modify thresholds "based on the measured stopping distance." The Board concluded Petitioner met its burden on claim 15 (patent owner did not specifically respond) and on claim 16.

Ground 2A — Grisham + Nixon → claims 7, 8, 9, 17, and 19

This is the GPS + progressive-alarm combination, and it is where the most developed motivation analysis sits.

• Claim 7 (GPS unit): Nixon teaches a GPS receiver determining absolute position and communicating it to collision-avoidance equipment; trains can be GPS-equipped.
• Claim 8 (use GPS + radio info to determine whether separation criteria are violated): the combined teachings supply both inputs.
• Claim 9 (progressive warning): Nixon's "beeping is faster as a target moves closer."
• Claim 17 (independent) and claim 19: same combination, applied to the single-module claim.

The stated motivation to combine, verbatim from the Board's analysis: Petitioner argued a POSITA would "supplement Grisham's UWB-based collision avoidance system with Nixon's GPS units because UWB accuracy is range-limited due to low transmission power that reduces its usefulness in stopping long trains," and because "GPS complements a UWB system by being effective at larger distances and tracking train travel paths." Under the proposed combination, "GPS would provide a better overall picture of where the train is and where other trains are, UWB allows that picture to be refined to the level of accuracy needed to assure that a collision does not occur."

That is the canonical KSR "complementary benefits" rationale, and it is also precisely the architecture the ’131 patent itself advocates ("a combination of distance sensors so that the CAS is adapted to detect vehicles that are either close or far away"). The patent's own specification therefore confirms rather than rebuts the motivation.

Notably, the Board rejected every patent-owner counter-argument: that UWB would interfere with GPS (the FCC report showed "various entities were using UWB and GPS together years before the '227 invention and there were solutions available"); that GPS accuracy of several meters defeats motivation (GPS still "allows positioning at larger distances and provides additional information, such as heading and acceleration"); and that GPS-over-UWB communication only works within UWB range (irrelevant, because GPS gives the host's own position "regardless of whether that vehicle is within UWB range of another vehicle").

Ground 2C / 2D — Grisham + Nixon + Richardson (claim 18) and + Douglas (claim 20)

Claim 18 requires the module to "receive calibration information related to a length of the rail vehicle, [and] a mounting location of the first [and second] wireless communications antenna." Richardson supplies the multi-radio geometry that makes such calibration necessary ("length information would be necessary in the system described in Richardson because it would facilitate determining the width of all zones"). Claim 20 adds Douglas's central tracking unit.

This is a direct mirror of the ’131 patent's own "commissioning" disclosure (specification: "an operator specifying the vehicle length in each direction from the one or more mounted TSMs"). The patent describes this as routine installation calibration — a strong indicium that it is not an inventive contribution.

Ground 3A / 3B — Suzuki, alone or with Grisham, (+ Richardson) → claims 1, 7–8, 11–14, 17

Suzuki is the closest single reference on the TOF element. It teaches an in-vehicle UWB device with communication and radar functions; when the vehicle detects its own ID in a received transmission, "the transmission timing and the reception timing … are sent to the vehicle-to-vehicle distance measurement part 126, and then … the value of a distance obtained by multiplying the time difference between these transmission timing and reception timing by the speed of light is divided by two."

That is textbook TOF. The Board-accepted motivation for the automotive→rail transfer:

"POSITAs would have understood that both cars and rail vehicles face the problem of avoiding collisions, and that applying a TOF determination of separation distance between cars to rail vehicles is actually less complex because rail vehicles have fewer degrees of freedom. … the same TOF calculations in Suzuki would be applied to rail vehicles without any material technical modification."

The "fewer degrees of freedom" rationale is technically sound and is the kind of "design incentive … in the marketplace" reasoning KSR at 421 endorses. In the alternative, Suzuki + Grisham is expressly motivated because "Grisham explicitly teaches the application of UWB systems to rail vehicles and even discloses a car-train communication embodiment."

E. Dependent-claim summary table

F. Secondary considerations — why they failed

Metrom proffered commercial success and industry praise for its AURA CAS product. The Federal Circuit affirmed the Board's rejection on nexus grounds under Fox Factory, Inc. v. SRAM, LLC, 944 F.3d 1366, 1373–75 (Fed. Cir. 2019):

1. No presumption of nexus. The Board found (on Metrom's CEO's own testimony) that AURA CAS had unclaimed "important features or components," including "key machine function monitoring and remote data reporting," that were "not insignificant." Where a product has important unclaimed features, the presumption of nexus does not attach.
2. No nexus by "direct result." Metrom failed to show the success was the "direct result of the unique characteristics of the invention." Its expert "conclusively stat[ed]" that the claimed features drive demand but did "not separately identify any unique characteristics … that were not already known in the prior art," and Metrom did "not argue that any inventive combination of known elements supports a finding of nexus."

Analyst observation: This is the doctrinally weakest point for the patent owner, and it is structural rather than evidentiary. The ’131 patent claims a combination of known elements (UWB ranging + GPS + display + adaptive alarms). Under KSR, a combination patent must show that the combination itself (not the individual known elements) drove the commercial success. Metrom never made that showing.

G. The dispositive post-grant outcome (do not analyze the claims in a vacuum)

As established in the previously generated sections of this analysis, the § 103 question for this patent is no longer open at the agency level:

• IPR2023-00468 Final Written Decision (Paper 71): claims 1–16 unpatentable as obvious; claims 17–20 not shown unpatentable, solely because the Board construed "data representing the separation distance" (limitation 17C) as requiring transmission of the computed distance, which Grisham did not do.
• CAFC Nos. 24-2223 et al. (May 11, 2026, nonprecedential): affirmed as to the ’227 patent and ’131 claims 1–16; reversed as to claims 17–20. The panel held the Board's construction was wrong — 17C means the data used in the TOF calculation, not the computed distance — and that "there is no dispute that Grisham discloses sending and receiving data used to determine a separation distance using the time-of-flight technique over the air," since Metrom conceded it at oral argument. Result: claims 17–20 also unpatentable.
• Judge Taranto, concurring-in-part and dissenting-in-part: would not reach the merits of the cross-appeal because Siemens never presented or preserved a claim-construction argument (party presentation / adequate preservation, citing Clark v. Sweeney, 607 U.S. 7 (2025), and In re Google Technology Holdings LLC, 980 F.3d 858 (Fed. Cir. 2020)).

Practical consequence for a § 103 opinion: The entire claim set has been held unpatentable, but the reasoning as to claims 17–20 rests on a claim construction adopted sua sponte on appeal — the exact ground Judge Taranto says was forfeited. Metrom has filed a combined petition for panel rehearing and rehearing en banc (dated June 2026). Until the mandate issues and rehearing is resolved, the claims 17–20 holding is the most fragile part of the outcome, not because the art is weak, but because of the procedural posture. The independent claim 1 holding, by contrast, is affirmed on a single reference and is far more robust.

I will not opine on the ultimate legal validity of the claims; that is a legal conclusion. What the record supports is: a POSITA would have found each claim obvious, and both the Board and (as to claims 1–16) the Federal Circuit so held.

H. Explicit uncertainties and limitations of this analysis

1. Claim text. I did not retrieve the verbatim text of claim 1's limitations after [1I], including [1J], or of claim 17's limitations 17D–17F and 17H. Those are reconstructed from the IPR and CAFC record, not quoted. The 17C text is quoted from the Federal Circuit opinion.
2. Douglas (U.S. 8,874,359) prior-art qualification. A patent numbered 8,874,359 would issue around late 2014, after the ’131 patent's May 19, 2011 priority date. It can only qualify as prior art via its own earlier filing/priority date (pre-AIA § 102(e)). The Board accepted it in the grounds; I have not verified its filing date and flag this as an unverified predicate. If its effective date postdates May 19, 2011, every ground that relies on Douglas (claims 4 and 20) is potentially unsupported.
3. McDaniel and Connell. I could not retrieve their patent numbers, titles, or publication dates in this pass. I have described their teachings only as characterized in the Board's opinion and the petition/patent-owner record. Their prior-art status and dates should be verified before reliance.
4. Richardson's exact citation. Retrieved as a 2010 Journal of Ultra Wideband Communications and Systems article by "Richardson" ("An Outdoor UWB Tracking System to Improve Safety of Semi-Autonomous…"). I do not have the full bibliographic string (volume/issue/pages) or a stable URL beyond the IPR exhibit references (J.A. and Ex. 1003 citations).
5. Ground designations. The Board's FWD uses "Ground 1A, 1B, 1C, 1D, 1E, 1F, 2A, 2B, 2C, 2D, 3A, 3B." My assignment of specific grounds to specific claims is drawn from the table of contents excerpt I retrieved (which lists the ground headings and page numbers) plus the CAFC opinion's description of which claims fell where. Some claim-to-ground pairings (notably claims 2, 3, 11–14) are inferred from the petitions' demonstrative headings ("Claims 1, 11 and 14 Are Obvious in View of Grisham") rather than quoted from the FWD.
6. Board internal inconsistency. As noted in § D (Ground 1D), the FWD contains statements about Grisham and absolute speed that are in tension. I have reported both rather than reconciling them.
7. Date inconsistency (carried forward and repeated deliberately). Search results include events through June 2026 (the CAFC opinion and the rehearing petition), which postdate the April 26, 2026 date in your prompt. I have reported them as found.
8. No independent prior-art search performed. Per your instruction I used the prior-art results already developed on this page. I did not run an independent novelty search, so this analysis does not rule out additional or better art, and it does not address anticipation under § 102.

I. Bottom line

Under § 103, the ’131 patent's claims are an assembly of known elements — UWB impulse-radio ranging (Grisham), TOF distance computation (Grisham + Richards; Suzuki), GPS absolute positioning (Nixon), multiple/offset transponders for long vehicles (Richardson), adaptive thresholds keyed to closing speed (McDaniel), progressive/graduated alarms (Nixon; Connell), and central tracking (Douglas). Each ground pairs a primary reference disclosing the claimed architecture in the identical field (Grisham for the rail-specific claims; Suzuki for the TOF element) with secondary references supplying a single known missing feature. The motivations are the ones KSR recognizes: complementary range/precision benefits, improvement of a similar device in the same way, fewer degrees of freedom, and avoidance of a known nuisance-alarm problem that the ’131 patent's own Background section concedes.

On the record of IPR2023-00468 and the May 11, 2026 Federal Circuit decision, all twenty claims have been held unpatentable as obvious, with the sole caveat that the claims 17–20 holding rests on a claim construction the panel adopted over a preserved-error objection by Judge Taranto, and is the subject of a pending rehearing petition.