US 6617961

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

US Patent 6,617,961 B1 — Analyst Summary

Bibliographic Data (from the patent document)

Foreign family (same priority, filed Nov 15, 2000 via PCT/US2000/031436):

• AU 17675/01 A (AU1767501A)
• CA 2,392,098 A1
• MX PA02005210 A
• WO 2001/037238 A1

Abstract (verbatim)

"A security system for a vehicle comprising a frame and a combination remote keyless entry and passive security system including at least one antenna mounted on the frame."

Plain-Language Overview of Each Independent Claim

Claim 1 — Challenge-signal generation with VID embedded by "combining."
A method of unlocking a vehicle door by wireless challenge/response. The vehicle controller generates a challenge signal containing a challenge data packet by (a) generating a random number with digits, (b) providing challenge data (which includes the vehicle controller's vehicle identification (VID) number), and (c) combining the challenge data with the random number to form the packet. The fob receives the challenge, generates and transmits a response, the vehicle receives the response, and the latch is moved from secured to unsecured. The novelty here is in how the packet is built: the VID is mathematically/logically merged into the random number rather than sent as a plain field.

Claim 3 — Fob-side authentication of the challenge before responding.
A method that adds a step to the basic challenge/response sequence: after the fob receives the challenge data signal but before it generates its response signal, the fob authenticates the challenge data packet. This is the broad "fob verifies the challenge" claim (dependent claims 4–16 add VID comparison, key-code-based extraction, fob initialization/programming, response authentication at the vehicle, and multi-fob arbitration timing).

Claim 17 — Response-packet construction using FID plus a calculated number.
A method focused on the fob side of message building. The fob generates a response data packet by (a) providing a random number (generated by either the vehicle controller or the fob), (b) providing a response data packet whose digits include the fob identification (FID) number, (c) generating a calculated number from the random number, and (d) combining the response data packet with the calculated number. The latch is unlocked on the vehicle's receipt of the response. (Note: the claim's preamble references "the fob controller" without previously introducing it — a drafting artifact worth flagging in any invalidity/infringement analysis.)

Claim 19 — Two-sided authentication: VID check in the fob, FID check in the vehicle.
A method in which the vehicle sends a challenge containing the VID; the fob authenticates by determining whether the packet's VID matches the VID stored in the fob; if so, the fob sends a response containing its FID; the vehicle then authenticates by determining whether the response's FID matches a stored FID at the controller; and only then does the latch unlock. This is the strongest "mutual identification" claim.

Claim 20 — Sleep-mode power management with staged (three-step) challenge validation.
A method where the fob has a microprocessor with a low-power sleep mode and a higher-power operating mode. The fob receives a challenge signal and authenticates it by successively applying a series of criteria to the challenge signal, and determines whether to bring the microprocessor out of sleep mode. Dependent claims 21–23 specify the three successive criteria (signal amplitude → timing → data-packet validation) and the return-to-sleep behavior.

Overall Technical Gist

The patent covers a vehicle security system that combines Remote Keyless Entry (RKE) (button-press, omnidirectional, ~30 m) with Passive Security (PS) (unidirectional/regionalized antenna patterns of ~2 m per door, plus a ~1 m passive-ignition pattern at the dashboard). Two vehicle PS antennas are spaced so their radiation patterns do not overlap, permitting door-specific passive unlocking. Fobs poll in sleep mode and apply a three-step validation (signal strength → bit timing → data-packet validation) to avoid waking on noise. Multi-fob conflicts are avoided by staggering each fob's response transmission by a predetermined delay assigned at fob "introduction."

Litigation / CAFC Docket Search — Result

I searched specifically for US 6,617,961 in connection with CAFC 2026 docket activity and litigation. I found no authoritative record of any Court of Appeals for the Federal Circuit docket, or any active litigation, involving US 6,617,961 in 2026. The patent's recorded legal status is "Expired – Fee Related" (term ran to its Nov 15, 2019 anticipated expiration date), which is consistent with there being no live enforcement proceeding. I also note that a search for the bare number "6617961" returns an unrelated JP 6617961 B2 (Panasonic IP Management, a position-confirmation system granted Dec 11, 2019) — this is a different jurisdiction and a different patent, not related to US 6,617,961.

Uncertainty disclosure: I do not have authoritative access to a live PACER/CAFC docket feed, so my "no 2026 CAFC activity" conclusion rests on the absence of any indexed record rather than on a direct docket query. If you need certainty on litigation history, that should be confirmed against PACER / the CAFC docket system and USPTO Patent Center's assignment and review records. All bibliographic and claim content above is taken from the patent document itself (Google Patents / Justia), which is authoritative for the patent text; the litigation statement is the only item resting on absence of search evidence.

I'll research litigation involving US patent 6617961. Let me search multiple sources.

Initial searches didn't surface litigation. Let me check litigation-specific databases directly.

Litigation Search: US Patent 6,617,961

Bottom line: I found no litigation involving US Patent 6,617,961. Based on the sources searched (Google Patents, USPTO, CourtListener, Casetext, Justia, Unified Patents portal references, and general web results), there is no record of this specific patent having been asserted in any district court, ITC action, PTAB proceeding, or Federal Circuit appeal.

Searches performed and what they showed

Important caution — a look‑alike result that is NOT this patent

My searching surfaced Strattec Security Corp. v. General Automotive Specialty Co., 126 F.3d 1411 (Fed. Cir. 1997). This is a genuine Strattec (the same assignee as the '961 patent) infringement case, but it involves U.S. Patent 4,492,482 (the "VATS" resistor‑in‑key patent), not 6,617,961, and it predates the '961 patent's 1999 filing by two years. It should not be counted as litigation of 6,617,961.

I also encountered an unrelated Japanese patent JP 6617961 B2 (Panasonic, a location‑confirmation system) and unrelated numeric strings ("6617961" in mining assay tables and other documents). These are false matches and not relevant.

Assessment

• US 6,617,961 (Strattec Security Corp.; "Security system for a vehicle and method of operating same") appears never to have been litigated.
• Its legal status is recorded as "Expired – Fee Related" (20‑year term reached ~2019‑11‑15), which is consistent with no active assertion.
• I cannot rule out very recent filings that a live docket database (e.g., Docket Navigator, PACER, Lex Machina) might show, but nothing in the public sources I could access indicates any case.

If you need a negative‑to‑a‑high‑degree‑of‑certainty answer, the definitive next step would be a paid search of Docket Navigator or a PACER "party/patent" search, since free aggregators do not exhaustively index every case. Based on the accessible sources, however, the answer is: no known litigation.

I'll verify the structured "no proceedings" block against live sources before writing, since the ODP ingest can lag recent filings.

The two searches return no AIA trial activity for US 6,617,961 — but they surfaced an inter partes reexamination of a different patent (6,465,961) that is informally called "the '961 patent." I need to confirm that's not our patent and check litigation-adjacent sources.

The confusion is resolved: 6,465,961 is a CAO Lighting semiconductor-light-source patent — unrelated. Let me run final confirmation searches on dedicated PTAB/patent-litigation databases.

Proceedings overview

Total AIA trial proceedings on file for US 6,617,961: zero. The USPTO Open Data Portal (ODP) structured "PTAB proceedings on file" block returns no IPR, PGR, or CBM for this patent, and targeted web searches across the PTAB/P-TACTS document corpus, Docket Alarm-style aggregations, and general web indexes surfaced no petition, institution decision, Final Written Decision, or appeal naming US 6,617,961 — so the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution-denied. Bottom-line defensive posture: the patent is untested at the Board, not "hardened" — every one of claims 1–27 (including independents 1, 3, 17, 19, 20) remains presumptively valid and fully enforceable in the sense that no PTAB panel has ever construed or canceled it. A defendant cannot point to an FWD and say "the claims are dead," but it also inherits no adverse estoppel and has a completely clean slate of ground-availability.

Two important caveats before the proceeding-by-proceeding section:

1. The canonical source is empty, and my searches corroborate it — but I could not complete a full second-pass docket sweep before my search budget expired. Treat "zero proceedings" as high-confidence-but-not-docket-verified. A direct query to PTAB E2E (https://ptacts.uspto.gov/ptabweb/) and the ODP trials API should be run for certainty.
2. A confirmed false positive exists and is a real trap. Multiple search hits discuss "the '961 patent" under inter partes reexamination control nos. 95/002,324 and 95/000,680 and IPR2023-00213, with rejections against claims 1–8 and 10–20. That is US 6,465,961 — a CAO Lighting / CAO Group semiconductor light source patent (heat-sink/plural-panel LED), asserted in Signify v. CAO Lighting. It is not Strattec's US 6,617,961. The informal "'961 patent" shorthand is the single likeliest source of a fabricated PTAB history for our patent. Do not import those outcomes.

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Proceedings

None. There is no proceeding to report under this heading.

Because the task instructs me not to invent proceeding numbers and there is nothing to enumerate, the itemized format (type / filed / status / panel / grounds / institution / FWD / settlement / appeal / defensive value) is inapplicable. Below I record the only adjacent records I found, so that no future analyst mistakes them for proceedings on this patent.

US 6,465,961 — reexamination 95/002,324 & 95/000,680; IPR2023-00213 (CAO Lighting, Inc.)

• Relationship to US 6,617,961: None. Different patent, different owner, different technology, no priority claim between them. Coeval numbering only.
• Why it appears in searches: Its claims and reexam papers repeatedly refer to it as "the '961 patent."
• Status (for hygiene only): Inter partes reexaminations in Art Unit 3992 (Examiner Kielin), with claims 1–8 and 10–20 rejected over Begemann (WO 00/17569), alone and in view of Waitl (CA 2,260,389) and Shimizu; a later IPR (Signify/CAO) addressed General Plastic discretionary-denial and printed-publication issues.
• Defensive value for a US 6,617,961 defendant: Zero. Cite it only to rebut an opponent who confuses the numbers.

Pre-AIA reexamination (US 6,617,961) — none found

The patent has a filing/priority date of 1999-11-15, so it was theoretically exposed to the pre-AIA ex parte and inter partes reexamination regimes (replaced by IPR/PGR/CBM on 2012-09-16). I found no reexamination certificate, no reexam request, and no Central Reexamination Unit action for US 6,617,961. Its claims are as-issued.

AIA trials (US 6,617,961) — none found

• IPR/PGR: no petition identified. Note that a PGR was legally unavailable in any event — PGR applies only to patents with an effective filing date on or after 2013-03-16, and this patent's effective filing date is 1999.
• CBM: no petition identified, and CBM eligibility is doubtful on its face — the claims recite a vehicle door latch and RF challenge/response, not a "financial product or service" or a technique for processing data used in the practice, administration, or management of a financial product. A CBM theory would be a stretch.
• Appeal to the Federal Circuit: none identified (consistent with the previous section's finding of no 2026 CAFC docket activity). This is a corollary of there being no FWD — there is no agency decision to appeal, and § 141/319 jurisdiction attaches only to a Board decision.

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Strategic summary

Claim status: every claim of US 6,617,961 is UNTESTED. There is no narrowed set. Claims 1, 3, 17, 19, and 20 are independent and in force as issued; dependent claims 2, 4–16, 18, and 21–27 stand with them. Nothing has been canceled, nothing has been confirmed by the Board, and nothing has been construed by a panel. If someone asserts this patent, the invalidity case must be built from scratch on the public record of the art — with the caveat that the patent's own prosecution record and any district-court Markman are the only interpretive guidance that exists.

Estoppel landscape: there is none to inherit, and none to worry about. Because no IPR/PGR was ever instituted, there is no § 315(e)(2) estoppel binding any party, and — importantly — no petitioner-privity estoppel to trap a co-defendant you might want to join or a supplier you might want to indemnify you. All prior-art grounds remain available: § 102(a)/(b) anticipation, § 103 obviousness, and the full range of printed publications, patents, and (in litigation, unlike IPR) system/on-sale/public-use prior art. There is also no 35 U.S.C. § 325(d) "same or substantially the same art" obstacle to a new petition, since the Office never evaluated this art in an AIA trial, and no § 315(b) one-year bar has been triggered by service of a complaint that I can identify.

Pattern signals: none of the usual signatures. No repeat petitioner, no serial petitions, no General Plastic / Fintiv dynamics, no defensive aggregator (Unified Patents or similar) visible in the chain, and no patent-owner PTAB-appeal aggression. The assignee, Strattec Security Corporation, is an operating automotive-access supplier (NASDAQ: STRT) rather than a litigating NPE — its 10-K/10-Q contingency notes describe IP matters as routine and immaterial, and its only notable Federal Circuit footprint I can identify is the unrelated 1997 Strattec v. General Automotive Specialty, 126 F.3d 1411 (VATS-key case). The most plausible explanation for the thin record is simply that the patent expired for fee-related reasons on its 2019-11-15 anticipated expiration and was never worth an AIA attack.

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Recommended next steps

1. Run the two authoritative queries I could not complete. Hit PTAB E2E at https://ptacts.uspto.gov/ptabweb/ and the ODP trials API/docket for "6,617,961," and pull the full file history from USPTO Patent Center (https://patentcenter.uspto.gov/). Confirm in the Patent Center "Reexaminations" and "Post-Grant" tabs that no reexam certificate or trial document is filed. My conclusion rests on an empty canonical block plus corroborating searches, not a completed docket sweep — flag that residual uncertainty.
2. Confirm the litigation history against PACER (this task sits downstream of the prior section's litigation search, which also found nothing). "Patent expired and never asserted" and "patent asserted but I can't see the docket" lead to very different defensive strategies; PACER/ CourtListener (https://www.courtlistener.com/) will disambiguate.
3. Do not treat the expired-for-fees status as a defense. Damages-recovery-only exposure is real for the pre-expiration period: a defendant can still be liable for infringement occurring on or before 2019-11-15, and if maintenance-fee lapse caused the expiration, intervening rights under 35 U.S.C. § 41(c)(2)/§ 27 could theoretically apply to unexpired-claim revival scenarios — but here the term ran to its natural 20-year date, so the cleaner path is invalidity and non-infringement of the pre-expiration conduct.
4. If you intend to file an IPR, treat it as a first impression, not a follow-on. There is no prior panel construction to lean on, and you must independently establish that each challenged claim is unpatentable — the Board has never touched this specification, so the § 112 indefiniteness flags already noted in the claim summary (e.g., claim 17's preamble reference to "the fob controller" with no antecedent, and the VID/key-code "combining" versus "separating" terminology) will be live issues on claim construction.
5. Preserve the false-positive warning. If any internal invalidity memo or third-party report cites "the '961 reexam" canceling claims 17 and 19 (Begemann) as applicable here, correct it immediately: that is US 6,465,961 (CAO Lighting), and claims 17 and 19 of that patent are different subject matter entirely.

I'll run targeted searches to reconstruct the assignment chain and check for any post-issuance transfers.

Let me check the USPTO Assignment Center record and look for any post-issuance transfers involving Strattec entities.

Let me verify the assignment record directly and confirm Strattec's corporate status.

Assignment & Ownership Analysis — US 6,617,961 B1

Scope note / confidence caveat: I could not obtain a direct, page-level read of the USPTO Assignment Center record (assignmentcenter.uspto.gov) with the tools available for this run. The assignment data below is drawn from the assignment event as indexed on the patent's Google Patents legal-events record and from Google Patents/USPTO-derived bibliographic data. No reel/frame number and no recording correspondent were surfaced by those sources. I am explicitly not inventing reel/frame numbers or attorney names to fill that gap. Where a field is unknown, I say so.

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Inventors

All three are Wisconsin-resident inventors and the application was filed 1999-11-15 with assignment of their interests to Strattec executed/recorded the same day. Two of the three (Janssen, Buczkiewicz) also appear as co-inventors on other Strattec filings in this era, which is consistent with a stable, long-tenured in-house engineering team rather than a group assembled for a one-off filing.

Unusual-pattern check: Not present. There is no evidence of inventors departing the original assignee within 12 months of filing, and no inventor-carve-out or re-assignment to a successor entity. The inventors assigned cleanly to their employer and never reappear as assignors downstream. No fire-sale precursor signal here.

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Original assignee

STRATTEC SECURITY CORPORATION (Milwaukee, Wisconsin) — named as original and current assignee on the face of the patent.

• Primary line of business: Manufacturer of automotive access-control hardware — mechanical and electronically enhanced locks and keys, fobs, passive-entry/passive-start (PEPS) systems, ignition lock housings, latches, power sliding-door/liftgate/decklid systems, and door handles. Formed in 1994 as a Briggs & Stratton subsidiary and spun off as an independent public company on 1995-02-27 (NASDAQ: STRT).
• Did they ship a product embodying the claims? Yes — and this is the key operating-company indicator. Strattec is the self-described "world's largest producer of automotive locks and keys since the late 1920s," and its current 10-K/Annual Report product list explicitly includes "fobs, passive entry passive start systems (PEPS)" — i.e., the combination RKE + passive-security fob-and-antenna architecture that is the subject of this patent. Strattec components are designed into a large list of North American vehicles (GM, Ford, Stellantis and others). The patent arose from Strattec's own Advanced Development Group work on electronic access control, not from an acquisition.
• Current status: Operating. Publicly traded (STRT), Milwaukee HQ, ~29+ years independent as of the 2024 annual report, with operations in the U.S. and Mexico. Not bankrupt, not dissolved, not acquired. Strattec has formed subsidiaries/joint ventures over the years (STRATTEC POWER ACCESS LLC, formed FY2009 with WITTE Automotive to acquire Delphi's North American Power Products Group; STRATTEC Advanced Logic LLC, formed FY2013 with Actuator Systems LLC), but no assignment of this patent to any of them is recorded.

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Assignment timeline

Only one assignment is recorded for this patent. It is the original inventor-to-employer assignment; there are no post-issuance assignments of any kind.

• 1999-11-15 (executed) / recorded 1999-11-15 — Reel/Frame: not surfaced by available sources (explicitly not fabricated)
  • Conveyance: Assignment of Assignors' Interest (original assignment)
  • Assignor: Robert T. Buczkiewicz; David C. Janssen; Henry N. Wagner (joint inventors)
  • Assignee: STRATTEC SECURITY CORPORATION
  • Correspondent: not determinable from the sources available to me. The indexed record does not expose an attorney/agent of record. I will not guess a name or firm. (If you need this field, it must be pulled directly from Assignment Center — see verification link below.)
  • Context: Original inventor-to-employer assignment at filing — not an acquisition, fire-sale, securitization, NPE transfer, or change of name. Routine in-house practice: the inventors assigned on the same day the application was filed.

Post-issuance chain: none. The patent issued 2003-09-09, ran its full term, and reached anticipated expiration on 2019-11-15 with Google Patents/ODP legal status "Expired – Fee Related." No assignment, security interest, license-of-record, merger, change of name, or release appears anywhere after the 1999 filing entry. For a patent with a 20-year term and 16 years of post-issuance life, a complete absence of any recorded transfer is a substantive finding: Strattec retained ownership from filing through expiration.

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Timeline diagram

timeline
    title Ownership of US 6617961
    1999 : Filed by Strattec
         : Inventors assign to Strattec
    2003 : Patent issued
    2019 : Expired by term
         : No transfers ever recorded

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NPE / troll-pattern signals

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Verdict

Insufficient data — applying the task's own definition ("no records, or only the original assignment"). The Assignment Center record for US 6,617,961 contains only the 1999-11-15 inventor-to-Strattec assignment; there are no post-issuance links to evaluate for NPE patterning.

Justification: The sole recorded conveyance is the original assignment of 1999-11-15 from inventors Buczkiewicz, Janssen and Wagner to STRATTEC SECURITY CORPORATION, with no subsequent transfers before the patent's 2019-11-15 term expiration. Because the chain has exactly one link, signals 3, 4 and 5 (which all require multiple transfers or a litigation trigger) are structurally inapplicable, and signals 1, 2, 6, 7 and 8 are affirmatively not present — there is no shell LLC, no known asserter, no bankruptcy, no privateering and no defensive aggregator anywhere in the history. On the evidence available, this is the ordinary profile of a long-held operating-company patent (a Strattec in-house PEPS/fob invention) that was never monetized or asserted and simply expired — not an NPE asset.

Two items I could not verify and am flagging rather than filling in:

1. Reel/frame and recording correspondent for the 1999-11-15 assignment — not exposed by the sources I could reach. Do not treat the absence as meaning the fields are empty.
2. My conclusion rests on the indexed assignment/legal-events records, not on a live page-level query of Assignment Center.

Verification links:

• USPTO Assignment Center search: https://assignmentcenter.uspto.gov/ (search by patent number 6617961)
• Legacy assignment search: https://assignment.uspto.gov/patent/index.html
• Google Patents legal events and bibliographic record: https://patents.google.com/patent/US6617961/en

Cross-reference note / no contradiction found: This is consistent with the previously generated summarizer section, which recorded "Expired – Fee Related," the 1999-11-15 priority/filing date, and Strattec as both original and current assignee. The only correction I'd add for the record: the previously generated section described Strattec's status as "operating, acquired, dissolved, in bankruptcy" as an open question — the resolved answer is operating (public, NASDAQ: STRT), never acquired, never in bankruptcy.

I'll search for the patent's cited prior art references, which weren't included in the truncated full text I was given.

The citation list wasn't in my provided text. Let me search specifically for the front-page "References Cited" on this patent.

Let me try to pull the patent's front-page citation list from full-text patent databases.

Prior Art Analysis — US 6,617,961 B1

⚠️ Critical limitation up front (read this before the citation tables)

I was unable to retrieve the actual "References Cited" list from the front page of US 6,617,961 B1. I must flag this rather than fabricate citations.

The authoritative full text supplied to me for this analysis begins at the Classifications section and jumps directly to "Cited By (62)" — the front-page prior-art sections ("Patent Citations" / "References Cited" and the "Similar Documents" section) were not included in the fetched text, and my follow-up searches for the citation list returned only truncated snippets. I searched Google Patents, uspto.report, FreePatentsOnline, Justia and general web indexes for the front-page reference list and could not recover it. Given the operating rule against fabrication, I will not invent U.S. patent numbers, dates and titles for references I have not verified.

What I can deliver, with grounding, is set out below.

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1. USPTO record check for patent number 6617961

Numeric-ambiguity note (per the "do not auto-correct" rule): searching the bare string "6617961" also surfaces an unrelated JP 6617961 B2 (Panasonic IP Management, position-confirmation system, granted 2019-12-11). That is a different jurisdiction and a different patent and is not related to US 6,617,961. I have excluded it.

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2. What the "citations for 6617961" actually consist of — and why the direction matters

There are two distinct citation sets, and conflating them is the most common analytical error here:

(a) Forward citations — "Cited By (62)" — retrieved, but legally irrelevant to § 102

Google Patents lists 62 later documents citing US 6,617,961 B1. These are reverse citations (they cite '961; '961 does not cite them). None can anticipate under 35 U.S.C. § 102, because § 102 requires a reference to qualify as prior art — i.e., its effective date must precede the '961 patent's 1999-11-15 filing/priority date. Every entry I could read in the "Cited By" list has a priority date of 2000 or later. The earliest are:

(List in my source is truncated at US 9,911,262 B2.) These documents are useful for landscape/obviousness context and for tracking claim-drafting descendants of '961, but they are not § 102 prior art and I will not map them to "anticipates claims X."

(b) Prior art cited by '961 (front-page "Patent Citations") — not recovered

This is the set the task actually targets, and it is the set I could not verify. I want to be explicit: any specific legacy U.S. patent numbers and dates I assigned to this list would be reconstructed from memory, not from the record, and that violates the no-fabrication rule. I am therefore not filling in the table.

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3. Prior art I can ground from the patent text itself

The specification does identify its prior art and one incorporation-by-reference. These are verifiable from the authoritative text.

3.1 Three named prior-art system classes (applicant's own characterization)

These three categories are recited verbatim in the "BACKGROUND OF THE INVENTION" and "Definitions" sections of the '961 text (Google Patents, US6617961B1, #1).

3.2 The only specific document '961 itself identifies

"The latch mechanism of the preferred embodiment is shown and described in U.S. patent application Ser. No. 09/408,993, entitled Modular Latch Apparatus and Method, filed on Sep. 29, 1999, and which is incorporated herein by reference."

This is the sole concrete document reference in the body. It is an incorporated-by-reference teaching (mechanical latch), directed to the latch mechanism of claims 1/3/17 preamble and not to the challenge/response subject matter — so it is weak § 102 art for the asserted inventive matter, but it is nonetheless the one citation I can confirm from the record.

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4. Best-effort § 102 mapping framework (claim-directed, not citation-verified)

Because I cannot map specific references to specific claims, here is the claim-scope map you would populate once the actual References Cited list is pulled. I've grouped claims by the distinct inventive concept each covers so you can slot references in.

Practical caveats worth flagging for whoever continues this analysis:

• The multi-fob staggering claims (14–16) recite "a predetermined time period," which is functional language that broad prior art on slotted polling could read on.
• Claim 17's preamble references "the fob controller" without antecedent introduction — a drafting artifact I flagged in the earlier summary; it matters for both § 112 and claim-charting.
• Claims 1, 3, 17, 19 and 20 are the independent claims; 1–2 and 17–18 are the only claims reciting the packet-construction ("combining"/"interspersing") concepts, which are the features most likely to survive a § 102 attack.

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5. Verification note and recommended next step

What I verified from the record: bibliographic data, the three named prior-art classes (RKE/PS/MPS), the incorporated application 09/408,993, the full claim set, and the 62 forward citations and their post-1999 priority dates.

What I could NOT verify: the front-page "References Cited" list (U.S. patent documents, foreign patent documents, and other publications cited by the examiner or applicant). It was absent from my source text and my searches did not recover it. I deliberately have not fabricated it.

To complete the task as specified, the citation list should be pulled directly from:

1. USPTO Patent Center / Patent Full-Text (PatFT) for US 6,617,961 — the "References Cited" section, or
2. the front page of the granted patent PDF (US6617961B1), or
3. Google Patents → https://patents.google.com/patent/US6617961B1/en → the "Patent Citations" table (distinct from "Cited By").

One relevant data point I did surface while searching: US 6,617,961 B1 appears in the search-report "A"-category documents of later filings — e.g., WO 2007/074354 A1 (Renault Trucks; PCT/US2005/…, priority 2005-12-29) cites "US 6 617 961 B1 (JANSSEN DAVID C ET AL) 9 September 2003" as a category-A document, and CN 100547214 C lists US6617961B1 among its [56] references (patentimages.storage.googleapis.com/b8/39/ee/0fd895e07b9ec8/CN100547214C.pdf). These confirm the patent's recognition in the passive-entry art but are again reverse citations, not prior art against '961.

If you can supply the patent's front-page PDF text or the Google Patents "Patent Citations" block, I will produce the full per-reference table (citation, dates, description, and claim-by-claim § 102 mapping) as specified.

I'll research the prior art referenced on this patent's page before building the § 103 analysis.

Let me pull the actual "References Cited" (backward citations) from the patent's front page and citation listing.

Obviousness Analysis — US 6,617,961 B1 under 35 U.S.C. § 103

Patent: US 6,617,961 B1, Security system for a vehicle and method of operating same (Strattec Security Corp.; filed/granted as noted in the prior sections)
Priority / critical date: November 15, 1999 (pre-AIA § 103 governs)
Claims analyzed: 27 (independent claims 1, 3, 17, 19, 20)

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0. Preliminary: what the "Prior Art section of this page" actually contains (and one contradiction to flag)

Before applying § 103 I have to be precise about the evidentiary record, because the earlier generated sections and the current task treat the page's prior-art content differently.

The supplied Google Patents page (https://patents.google.com/patent/[US6617961B1](/patent/US6617961B1)/en) contains four distinct bodies of "prior art" material:

Contradiction / limitation flag. The earlier "Patent summary" and "Litigation summary" sections correctly treated "Cited By (62)" as a forward-citation listing, but the prior-art analysis now requested presumes a "Prior Art section" with references to combine. The backward-citation table that Google Patents normally renders for this document was not included in the fetched page text, and my attempts to retrieve it (searches for the front-page "References Cited" block, the patentimages front-page PDF, and the FPO record) returned only the full-text/claim pages, not the citation table. I therefore cannot enumerate the specific references the examiner applied. Any § 103 ground below that names a reference not appearing verbatim in the supplied page text is labeled with an explicit confidence level and must be verified against the front page (patents.google.com → "Patent Citations") before being relied on.

I also flag a second, smaller inconsistency carried forward from the earlier sections: "Expired – Fee Related" is Google's status label (failure to pay maintenance fees), which is not the same thing as the separate "2019-11-15 Anticipated expiration" event field. The earlier summary's phrasing ("term ran to its Nov 15, 2019 anticipated expiration date") conflates the two. If the fee-related lapse occurred earlier, the enforceable term ended earlier than 2019. This does not affect the § 103 analysis (expired patents are still invalidatable art/claims for defensive purposes), but the dates matter for any reliance on the patent as of a given time.

Finally, as the earlier section noted, claim 17's preamble references "the fob controller" without antecedent introduction. That drafting defect drives construction of claim 17 (see § 2 below) and materially affects how easy claim 17 is to invalidate.

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1. Governing standard

• Pre-AIA 35 U.S.C. § 103(a): claims are invalid if the differences between the claimed subject matter and the prior art are such that the subject matter as a whole would have been obvious at the time of the invention to a person having ordinary skill in the art.
• Graham v. John Deere Co., 383 U.S. 1 (1966): scope/content of the prior art; differences; level of ordinary skill; secondary considerations.
• KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007): "[I]f 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." A combination is obvious where it is "the product of ordinary creativity," or where there is a "design incentive," "market demand," or the field presents only "a finite number of identified, predictable solutions."
• MPEP 2143 exemplary motivations: (A) predictable combination of known elements; (B) simple substitution of a known element for another; (C) known technique to improve a similar device; (D) applying a known technique to a known device ready for improvement; (E) "obvious to try"; (F) design incentives / market forces; (G) some teaching, suggestion, or motivation in the art.

Level of ordinary skill (proposed). A bachelor's degree in electrical engineering (or equivalent) plus 2–4 years of experience designing RF remote-entry, immobilizer, or access-control systems; or a lesser degree with 5+ years of such experience. This is the skill level a 1999 examiner would likely adopt for the B60R 25/24 and G07C 9/00 arts in which this patent is classified (see the "Classifications" block of the page).

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2. Key claim-term construction (construed to the specification)

These constructions come from the patent's own text and are decisive for obviousness, because the specification reads on very broad functional language:

Because "combining" is expressly defined to cover any mathematical or logical operation, the specification surrenders any argument that the claim requires a particular interleaving scheme — the only interleaving-specific limitation is claim 2 (and its mirror, claim 18).

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3. The prior art on this record

3.1 Admitted prior art (from the patent itself) — highest evidentiary value

The supplied page's Background/Definitions sections are the applicant's admissions:

1. RKE prior art — "a portable transmitter, or fob, that transmits a signal to an antenna mounted on a vehicle in response to a user request. The signal causes a vehicle controller to move a lock mechanism… from a secured… to an unsecured… state or vice versa"; fob has lock/unlock/panic buttons.
2. PS prior art — "a fob that transmits a signal requesting a vehicle controller to change the state of the latch mechanism… The initiation of the signal occurs when the fob is adjacent to the vehicle."
3. MPS prior art — "similar to the PS system except that the initiation of the signal requesting the lock mechanism to move from an unsecured state to a secured state occurs when a user actuates a door handle on the vehicle frame."
4. Mechanical key — metal key/bitting/receptacle.
5. Incorporated-by-reference latch — U.S. app. Ser. No. 09/408,993, Modular Latch Apparatus and Method, filed Sep. 29, 1999 (same assignee).

Admissions 1–3 are unusually powerful: they establish that both the button-initiated remote path and the proximity/handle-initiated passive path, each with a fob, a vehicle antenna, and a controller-driven latch state change, were old and well known before November 15, 1999. The patent's own "Summary" concedes the asserted advance is the combination of these two known system types ("the invention can remotely secure or unsecure a vehicle and passively unsecure a vehicle with the same fob").

3.2 Contemporaneous art in the same field (flagged for verification)

From a USPTO PTAB petition document surfaced in search, the following are real, pre-1999 references in exactly this field (I could not re-verify each reference's disclosure in this session and I am not asserting they were examiner-cited against '961):

Source for the above attributions: https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1550976](/patent/1550976)/download-documents (petition document excerpt). These should be pulled and read before any ground is asserted.

3.3 General knowledge in the art as of Nov. 1999 (no reference number asserted)

I state these as PHOSITA-level knowledge rather than as specific references, and I flag that accordingly:

• Code-hopping / rolling-code RKE (e.g., KeeLoq-class hopping-code transmitters/encoders) was a shipping commercial technology throughout the 1990s; challenge–response with a key-derived expected answer was textbook.
• Bidirectional (mutual) authentication between an interrogator and a passive token, using a random challenge (nonce) plus a shared secret, was standard practice in RFID/access-control and immobilizer systems.
• Low-power "polling"/sniff receivers that stay in a micro-power state and wake only on a valid carrier, RSSI threshold, preamble, or baud/timing check, were standard in pagers, tire-pressure monitors, and RKE receivers.
• Slotted/TDMA transmission to arbitrate multiple transmitters was textbook.
• Data interleaving and scrambling of the digits/fields of a packet were everyday digital-communication techniques.

3.4 What the page itself shows about the state of the art

Two items from the supplied page are worth noting because they corroborate that key features were regarded as known and ripe for combination:

1. The patent names a commodity transceiver. The specification states the vehicle PS transceiver and fob transceiver are "preferably an RF Monolithics TR3001 ASH transceiver." The ASH family provides on-chip received-signal-strength and carrier/interrupt outputs — i.e., the hardware that performs claim 20's "successive criteria" gatekeeping was a catalog part, not an invention.
2. Google's CPC assignments. The page assigns G07C 2009/00365 ("…in combination with a wake-up circuit") and G07C 2009/00373 ("whereby the wake-up circuit is situated in the lock"). Those classes exist because wake-up circuits in the lock/vehicle side of passive-entry systems were an established, classifiable art.

3.5 What may not be used

The "Cited By (62)" table is not prior art. Every entry post-dates the Nov. 15, 1999 critical date (earliest: US 2003/0184431, priority 2000-10-23). It is useful only as context showing how quickly the industry re-combined passive entry + RKE (e.g., Lear's "Integrated passive entry and remote keyless entry system," US 2006/0114100, priority 2004-11-30; Lear's "Energy efficient passive entry system," US 2006/0255908, priority 2005-05-13). That is not a § 103 teaching, and I am not using it as one.

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4. The claimed subject matter, decomposed

Nearly every claim reduces to four functional blocks, all of which map onto the admitted art:

• (P) Passive trigger — handle actuation or fob-in-field (admitted MPS/PS art).
• (C) Challenge/response crypto — random number, key code, expected answer (known RKE/immobilizer art).
• (L) Latch state change — controller-driven lock/unlock (admitted RKE/PS/MPS art).
• (A) Power/anti-false-trigger architecture — sleep/poll, staged criteria (known low-power receiver art).

The only features that are not flatly admitted are: (i) packing the VID into the same packet as the random number by "combining" (claims 1, 2, 17, 18); (ii) fob-side validation of the challenge before responding (claims 3–13, 19, 25–27); (iii) per-fob staggered response timing (claims 14–16); and (iv) staged wake-up criteria (claims 20–23).

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5. Grounds of obviousness

Ground 1 — Claims 1 and 2: admitted PS/MPS art + challenge–response RKE art + known field-interleaving

Combination: (a) the admitted PS/MPS systems of the '961 Background (fob, vehicle antenna, controller, latch state change, handle-actuated initiation) in view of (b) conventional challenge–response/rolling-code vehicle RKE (e.g., U.S. 5,252,966, remote keyless entry system for a vehicle, subject to verification) in further view of (c) the ordinary digital-communication technique of interleaving/scrambling data fields into a single packet.

Element map for claim 1:

Motivation (KSR/MPEP 2143(A), (C), (F)): A PHOSITA seeking to add anti-replay and mutual authentication to an admitted MPS passive-entry system would predictably adopt the challenge–response scheme already standard in RKE/immobilizers. Packing the identifier and the nonce into one packet rather than two is the classic airtime/power conservation measure — precisely the benefit the patent itself claims ("[b]y going through a three-step process, the fob consumes less power"), and the same reduction in the number of transmissions that the '961 specification says reduces power consumption in the fob and vehicle. Interleaving the digits is a known technique applied to a known device ready for improvement — MPEP 2143(C)/(D). No reference teaches away.

Claim 2 (interspersing digits): the specification's own words are "a scrambling algorithm such as a placement function… the four digits of the VID are intermingled with the twelve digits of the random number." That is the definition of interleaving. Claim 2 is very likely obvious, and arguably anticipated by any interleaved framing art.

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Ground 2 — Claims 3–12, 19, 25–27: admitted PS/MPS art + bidirectional challenge–response art + fob key-learning art

Combination: Ground 1's combination plus (d) conventional RKE fob programming / "learn mode" art (transferring vehicle ID and key code to a fob upon pairing).

Motivation: Once the PHOSITA adopts the challenge–response handshake of Ground 1, the two-step authentication of claim 19 is the natural and predictable division of labor: the fob screens for its own vehicle (saves the fob from power-wasting responses to foreign challenges — the very concern the patent raises for false signals), and the vehicle screens for an enrolled fob (prevents unauthorized fobs). The applicant's own stated advantage — "the fob consumes less power since it does not attempt to signal a vehicle door based on a false input signal" — is a predictable result of a known design choice, which under KSR supports obviousness rather than rebutting it. Likewise, key-learning (claims 7–8) was the standard way every RKE system of the era enrolled a second fob; the spec's own description of "introducing" a fob reads as a description of routine learn mode (transmit VID/key/FID to the fob, store).

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Ground 3 — Claims 14–16: + multiple-transmitter arbitration/timing art

Combination: Ground 2 plus (e) conventional multiple-access arbitration (slotted transmission, staggered/back-off timing) in RF systems, and the known practice of assigning per-transmitter identities.

Motivation (MPEP 2143(A), (F)): The patent itself states the problem and the result: "[t]o prevent confusion at the vehicle microprocessor… the second fob… transmits its response signal a predetermined amount of time after the first… to allow the first response signal adequate time to begin transmission," and the advantage is that "more than one fob [can] be used… without having the fobs conflict." Collision avoidance by time separation is one of the oldest and most predictable techniques in multiple-access RF; applying it to fobs sharing one vehicle antenna is a predictable combination of known elements with predictable results.

⚠️ This is the weakest prong of the obviousness case. Claims 15/16 require a predetermined delay, and the spec assigns that delay at fob-introduction time (first fob = delay zero, second fob = first predetermined period, etc.). An obviousness ground built on generic random back-off (CSMA-style) will not read on "predetermined… a predetermined time period" tied to fob enrollment order. A defendant would need art showing per-device assigned transmit slots/delays. Flag this to the analyst as the claim family most likely to survive a § 103 challenge absent targeted art.

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Ground 4 — Claims 17 and 18: fob-side response construction (mirror of Ground 1)

Combination: the admitted PS/MPS art plus conventional challenge–response/rolling-code art plus the same interleaving technique as in Ground 1, applied on the return path.

Claim 17 recites: random number (from the vehicle or the fob), a response data packet including the FID, a calculated number derived from the random number, and combining the two. This is the return-path mirror of claim 1 and is supported by the same art and the same motivation (single-packet airtime reduction; anti-replay; obfuscation of the returned identifier).

Two construction-driven points that make claim 17 especially vulnerable:

1. Antecedent-basis defect. As flagged in the earlier summary, claim 17's preamble recites "a fob having a fob antenna," but the body recites "wherein the fob controller includes a fob identification (FID) number" — "fob controller" has no antecedent. Under the broadest reasonable/Phillips construction, this either (i) invalidates under § 112(b), or (ii) is read to import the fob controller by implication. In either reading the claim covers any fob that mixes its FID with a random-number-derived value, which is ordinary challenge–response construction.
2. The random number may be fob-generated. Claim 17 expressly permits "the random number… generated from a one of the vehicle controller and the fob." That eliminates any argument that the claim requires vehicle-originated freshness, removing the last possible distinction over the simplest two-message protocol art.

Claim 18 (interspersing digits) falls with claim 2.

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Ground 5 — Claims 20–23: sleep-mode power management with staged criteria

Combination: admitted PS art (fob in the field, low-power portable device) plus (f) conventional low-power receiver wake-up art (carrier detect / RSSI / squelch threshold, preamble or baud-timing check, and data validation before full wake) plus (g) the patent's own admitted use of the RF Monolithics TR3001 ASH transceiver, a catalog part with RSSI and interrupt outputs.

Claim 20's limitations, and why they are obvious:

Claim 21 (amplitude → timing → data-packet validation) is the exact standard receive chain of a low-power packet receiver (RSSI gate, then bit-timing/baud match, then CRC/packet check). Claim 22 (wake on amplitude alone) and claim 23 (return to sleep on timing failure or failed validation) are the two trivial variants of that ladder — an "obvious to try" choice among a finite number of predictable alternatives (KSR).

Motivation (MPEP 2143(B), (C), (G)): The patent states the goal — "the fob consumes less power since it does not attempt to signal a vehicle door based on a false input signal." Reducing false wake-ups to extend fob battery life was the dominant design pressure in passive-entry development in the late 1990s (a pressure the page's own forward citations show continuing for a decade, e.g., Lear's "Energy efficient passive entry system," 2005 priority — context only, not prior art). Using a menu of known filtering criteria in sequence to gate a wake-up is the substitution of a known element for a known element to achieve a predictable power saving. No reference teaches away from staged validation.

⚠️ Counter-argument to anticipate. A patentee would argue that the ordering — validate amplitude before waking the processor, and do the amplitude analysis in hardware (the spec's "RC circuit or a crystal clocked flip-flop within the fob PS transceiver") while the uP stays asleep — is a specific architectural insight. That argument does not help claim 20 through claim 23, because none of them recites hardware-based amplitude gating or any particular division between hardware and firmware. Claim 20 merely requires "successively applying a series of criteria" and "determining whether to bring the microprocessor out of the sleep mode," both of which are functional and broad. The narrowing detail lives only in the unclaimed specification.

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Ground 6 — Claims 24–26: near-certain obviousness (formalities)

Claim 24 re-recites generating/transmitting/receiving the challenge; claim 25 adds the response/validate/unlock loop; claim 26 adds FID extraction and comparison. These are combinations of Grounds 1 (or 4) and 2 with no new technical content, and claim 24 in particular is a restatement of steps already recited in claim 3's preamble. Under MPEP 2143(A) these add nothing patentable over the combined teachings.

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6. Motivation to combine — consolidated

A PHOSITA in November 1999 faced exactly the problem the patent states: the admitted PS/MPS systems unlock (or relock) on mere proximity or handle touch, wasting fob battery and risking unwanted unlock, while the admitted RKE system requires the user to press a button. The field supplied a finite set of identified, predictable solutions:

1. Merge the two known system types into one fob — the patent's own conceded advantage, and the explicit market demand of the period (one key, both functions).
2. Make the passive path bidirectional and authenticated — the standard way to prevent false-trigger responses; the fob must know it is talking to its vehicle before burning transmit power.
3. Gate the fob's receiver with a staged wake-up ladder — the standard low-power receiver technique, and demonstrably available off the shelf (the patent's own TR3001 ASH).
4. Packing ID + nonce into one interleaved/scrambled packet — a known technique that improves airtime, power, and obfuscation; the spec concedes "combining" is any mathematical or logical operation.
5. Arbitrate multiple fobs by time separation — the textbook solution to multiple-access collision.

Each addition yields only predictable results, and the patent asserts nothing more than those predictable results as its "advantages" (less power consumption, no unwanted unlocking, no multi-fob conflict, remote + passive from one fob). Under KSR, that is the hallmark of obviousness: "the combination of familiar elements according to known methods is likely to be obvious when it does no more than yield predictable results."

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7. Secondary considerations (§ 103 rebuttal / Graham factor 4)

On the record available:

• Teaching away: none. The specification disparages no prior-art approach; it treats RKE, PS, and MPS neutrally ("[v]arious systems and methods… have been presented in the prior art").
• Unexpected results: none asserted. The specification claims no test data, no measured power savings, and no result that would not follow from the known components.
• Long-felt need / failure of others: not established on this record. Passive entry with combined RKE existed commercially well before the 1999 filing (the applicant's own PS/MPS admissions describe it), which cuts against a long-felt-need narrative.
• Commercial success / industry adoption: the rapid proliferation of passive-entry-plus-RKE systems in the years after 1999 is some evidence of marketplace value, but any nexus would run to the unclaimed regionalized-antenna architecture (the ~2 m non-overlapping unidirectional patterns, the ~1 m dashboard ignition pattern) rather than to the claimed method steps — and the claims do not cover the antenna architecture. This is a significant nexus gap: the patent's commercially distinctive feature (door-selective passive unlock) is not claimed.
• Copying: no evidence on this record.

Net: on the record supplied, secondary considerations do not appear to rebut the § 103 grounds.

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8. Where an obviousness challenge is vulnerable (what would not fall easily)

For balance, and because the earlier sections emphasize accuracy over advocacy:

1. Claims 15 and 16 — the predetermined, enrollment-order-assigned inter-fob transmission delay. Generic collision-avoidance art (random back-off) does not read on "a predetermined time period," and the specification ties the delay to fob-introduction order. Needs targeted art.
2. The specific staged hardware architecture — if any claim were ever construed to require that amplitude analysis occur in hardware while the microprocessor remains asleep (claims 20–23 arguably do not), the analysis would tighten considerably. As written, though, the claims stay functional.
3. Any argument built on unretrieved citations is provisional. The single largest weakness in this memo is that I could not read the examiner's actual cited references (see § 0). The front page must be pulled.

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9. Bottom line

Overall: every independent claim appears vulnerable under § 103 to a combination drawn from the applicant's own admissions plus ordinary knowledge in the 1999 RKE/passive-entry/low-power-receiver arts. The claims that most resist the analysis are the narrow multi-fob timing claims 15–16; the claims that are broadest and most exposed are claim 20 (functional wake-up recitation) and claim 1 (because the specification defines "combining" as any mathematical or logical operation).

Practical note: because the patent is recorded as Expired – Fee Related, this analysis has historical/defensive value (invalidity of related continuations, family members AU 17675/01, CA 2,392,098, MX PA02005210, WO 2001/037238, and prior-art estoppel in later proceedings) rather than offensive value against a live assertion. I flag the earlier sections' caution on the "Expired" label — see § 0.

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10. Explicit uncertainties and contradictions (as required)

1. Missing record. The Google Patents backward-citation ("Patent Citations") table for US 6,617,961 was not present in the supplied page text, and my retrieval attempts for it failed. The specific references combined above therefore rest on (a) the applicant's admissions in the patent, (b) the incorporated Ser. No. 09/408,993, (c) one verified contemporaneous RKE reference (U.S. 5,252,966, "remote keyless entry system for a vehicle," subject matter confirmed via a USPTO PTAB document surfaced in search), and (d) PHOSITA-level general knowledge. Treat item (c) and the other pre-1999 numbers in §3.2 as requiring verification.
2. Contradiction flagged. The earlier "Patent summary"/"Litigation summary" sections treated "Expired – Fee Related" as meaning the patent ran to its Nov. 15, 2019 anticipated expiration. Those are two different fields on the page (a status label vs. an anticipated-expiration event). Not corrected here — flagged for reconciliation.
3. Contradiction flagged. The prior sections were generated with a fetch date of 2026-09-30; this task states the current date as April 26, 2026. The substantive content is unaffected, but the dates in the file are inconsistent.
4. No litigation/2026 CAFC activity. I did not independently re-verify the earlier "no litigation" conclusion in this session; I relied on the earlier sections. Nothing in the prior-art analysis changes it.
5. Numbers not auto-corrected. "Microchip PIC 12650X series" and "RF Monolithics TR3001 ASH transceiver" are reproduced exactly as printed in the patent. The former is almost certainly a typographical error for a PIC12C50x-family part, but I have not corrected it.

Recommended next steps to convert this into a usable invalidity position: (i) pull the front-page "References Cited" list from patents.google.com/patent/US6617961B1/en and USPTO Patent Center; (ii) pull and read U.S. 5,252,966 (Lambropoulous), U.S. 5,146,215 (Drori), and the vehicle multiplex references in §3.2; (iii) target dedicated art on predetermined slotted transmission timing assigned per transmitter for claims 15–16; and (iv) obtain the examiner's reasons for allowance from the file wrapper to see which limitation the examiner believed distinguished the admitted art.