US 6405047

I'll search for litigation and docket information on this patent number, then provide the summary.

Let me run a couple more targeted searches to check for any 2026 proceedings.

Search results for US 6,405,047

Litigation / CAFC 2026 docket check — negative result. I searched for Federal Circuit 2026 activity and district-court litigation tied to this number and found no docket, appeal, IPR, or litigation naming US 6,405,047. Two apparent "hits" were number collisions in other systems, not this patent:

• JP6405047B2 — a Japanese patent (linear motor / electric shaver support, Braun GmbH; registration 2018-09-21). Different jurisdiction, different subject matter. Not US 6,405,047. (Source: https://patentimages.storage.googleapis.com/6e/22/0a/cf39f5c2a8c2d4/JP6405047B2.pdf)
• A Solano County commodity code "6405047 CUPS, PAPER…" — unrelated procurement classification. (Source: https://app.solanocounty.gov/civicax/filebank/blobdload.aspx?BlobID=45735)

The CAFC full-text search returned Samsung/Federal Circuit cases, but none involving this patent. Treat the absence of litigation as accurate only for the sources I could reach; I cannot rule out a district-court filing that is not indexed in the open web results. I did not have direct USPTO PatentCenter/assignment API access in these results, so the following is grounded in the Google Patents record for the patent itself (https://patents.google.com/patent/US6405047/en), which is the authoritative text supplied.

---

US 6,405,047 B1 — Summary

Abstract (as published): "A device for tracking a mobile station's position in a mobile communication system. The device comprises a receiver for receiving single tone signals and positional information transmitted from at least three base stations; a tone phase measurer for measuring phase differences, dependent on propagation delay, of the tone signals on the basis of a base station's system reference time before propagation delay; and a mobile station's position calculator for calculating positional information of the mobile station using the measured phase differences and the positional information of the base stations."

Problem addressed. The specification frames the invention against the IS‑95/IS‑95B "Power‑Up Function" (PUF): the mobile station transmits a high‑power PUF pulse that adjacent base stations use to measure propagation delay. The patent states this only works during a call (traffic‑channel state), adds reverse‑link interference, and wastes mobile power. The disclosed alternative has base stations broadcast unmodulated tone signals and the mobile station do the measuring.

---

Plain-language overview of the independent claims

Independent claim 1 (device):
Two-part subject matter — (a) a receiver that receives tone signals from at least three base stations and receives the base stations' positional information from the service base station; (b) a tone phase measurer that measures phase differences of the tone signals that depend on propagation delay, measured against the base station's system reference time before propagation delay (the patent's "absolute system time"); and (c) a mobile-station position calculator that computes the station's location from those measured phase differences plus the base stations' known positions (the description says this is done by triangulation). Note: the granted text contains a typographical error — "receiving tone signals form at least three base stations" — which I have preserved rather than corrected.

Independent claim 10 (method): The method counterpart of claim 1, with the same three steps — receiving tone signals from at least three base stations and their positional information from the service base station; measuring propagation-delay-dependent phase differences of those tone signals relative to the base station's pre-propagation-delay reference time; and calculating the mobile station's position from the phase differences and the base stations' positions.

Dependent claims worth flagging (they add substantive concepts that could matter for scope/validity analysis):

• Claims 2–5 (device) / 11–14 (method): an absolute-system-time acquiring and maintaining part that derives the pre-propagation-delay base station time from (i) the base station's measured propagation delay Γ(n) of a message containing the mobile's PN sequence, (ii) the mobile's system-reference-time adjust amount ΔΓ(T), and (iii) the mobile's system reference T_ms(T), implemented by the equation T_ms(T) − ΔΓ(T) = T_bs(T) − Γ(n).
• Claim 6 / 15 and 7 / 16: a position tracking controller feeding the calculator base-station positional/ID information and feeding the phase measurer tone period/frequency, with that information carried over a common control channel (e.g., paging channel in IS‑95A).
• Claim 8 and 17: base-station transmitter structure — tone generator, carrier frequency generator, mixer, up-converter.
• Claim 9 / 18: base stations periodically transmit their tone signals at different time points (to avoid inter-modulation).

---

Uncertainty / caveats

• No litigation found, but not exhaustively verified. My keyword searches surfaced no CAFC 2026 appeal and no district-court docket for this patent. I could not query PACER/CourtListener or USPTO PatentCenter directly through the available tools, so this is "not found," not "confirmed none."
• Number collisions exist. The string "6405047" also matches JP6405047B2 (Braun linear-motor shaver patent) and an unrelated county purchasing code; neither relates to US 6,405,047.
• Inconsistent "cited by" counts in the source page. The Google Patents page shows two different tables — one listing 88 "Cited By" entries and another listing 170 — a discrepancy in the source itself that I am flagging rather than resolving.
• Expiry. The record states anticipated expiration 2019-12-01 with status "Expired – Lifetime." Any 2026 enforcement activity would face this term date, though I note that formally as an observation, not a legal conclusion.
• Assignee/inventor/date fields above come from the supplied patent record; I did not independently re-verify the chain of assignment against USPTO's assignment database.

I'll search for litigation involving US patent 6405047.

Initial searches returned irrelevant results (including a Japanese patent with the same number). Let me search patent litigation-specific databases.

No relevant hits yet. Let me try patent-specific litigation databases and other search angles.

Based on my searches, I could not identify any known litigation involving U.S. Patent No. 6,405,047.

Summary of Findings

No litigation found. My searches across general web sources, patent litigation-related results, and patent databases (including the Unified Patents portal and Justia) returned no records of any lawsuit, complaint, ITC action, or PTAB proceeding involving U.S. Patent 6,405,047.

What I did find (for context, not litigation)

1. The patent itself — U.S. Patent No. 6,405,047 B1, "Device and method for tracking mobile station's position in mobile communication system," inventor Yong-Woon Moon, assigned to Samsung Electronics Co., Ltd. Filed December 1, 1999 (priority to Korean application 98-52235, filed Dec. 1, 1998); granted June 11, 2002; classified primarily under H04W64/00 and G01S5/xx. Per Google Patents, its legal status is "Expired – Lifetime," with an anticipated expiration of December 1, 2019. (Source: https://patents.google.com/patent/[US6405047](/patent/US6405047)/en)

2. Citations, not suits — The patent appears only in citation/literature contexts:

   • It is cited by numerous later patents (the Google Patents record lists 88 "cited by" entries and 170 in one listing), e.g., Qualcomm and AT&T Mobility location-related patents — but citations are not litigation.
   • It cites six prior-art references (e.g., US4649543, US5293645, US5764188, US5900838, US6108556, US6308073).
   • It is cited as prior art in other patents, e.g., WO2010069338A1 (Siemens).

3. False-positive match (do not confuse) — A search for "6405047" returns JP Patent No. 6405047 (JP6405047B2), a Japanese patent for a "Linear motor and its support" owned by Braun GmbH. This is an unrelated Japanese patent that merely shares the same numeric suffix and is not U.S. Patent 6,405,047.

Important caveats

• I may be missing data. Not all patent litigation is fully indexed in free, publicly searchable form. District court suits (especially older ones that settled or were dismissed early), some ITC proceedings, and foreign actions may not appear in the sources I could reach. My tool access returned only partial/aggregated results, and several queries hit step limits.
• No positive evidence of litigation exists in what I retrieved, but absence of results in my searches is not proof that no litigation ever occurred.
• To be more definitive, I would recommend running a dedicated litigation search on:
  • Lex Machina or Docket Navigator (paid, comprehensive patent litigation databases),
  • Unified Patents Portal litigation/case list (https://portal.unifiedpatents.com/litigation/caselist),
  • PACER (federal dockets),
  • USPTO PTAB (PTAB Center / Patent Trial and Appeal Board filings),
  • USITC EDIS (Section 337 investigations).

If you can confirm with one of those databases and share the results, I can help interpret or memorialize them. As of my searches, however, I found no known litigation involving U.S. Patent 6,405,047.

I'll verify the canonical "no proceedings" finding with targeted searches before writing up.

The first pass returned only unrelated '047 references. Let me probe specifically and rule out a possible false positive I noticed.

One search fragment referenced an asserted "'047 patent" in Texas litigation — worth ruling in or out as a false positive.

Proceedings overview

Total AIA trial proceedings on file for U.S. Patent 6,405,047: zero — 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials, 0 PGRs, 0 CBMs. The patent has never been the subject of an IPR, PGR, or CBM in the USPTO Open Data Portal's structured record supplied in this prompt, and my independent web searches (PTAB petition documents surfaced via ptacts.uspto.gov, PTAB case aggregators, and general web) surfaced no petition, institution decision, Final Written Decision, or Federal Circuit appeal naming this patent. Defensive posture: because no tribunal has ever construed or canceled a claim of 6,405,047, every claim (1–18) is legally "untested," not "hardened." There is no IPR-based estoppel, no FWD to cite, and no canceled claim that removes an infringement theory from a demand letter. Conversely, there is no surviving-claims narrative either — the claims simply have never been adjudicated by the Board. Practically, this matters little today because the patent expired 2019-12-01 (anticipated expiration per Google Patents), meaning it cannot be asserted in a live infringement suit and an IPR on it would be of academic value only.

No proceedings to report

There is no proceeding number to list. Per the instructions, I will not invent one. The "PTAB proceedings on file" block is empty, and nothing in my searches fills that gap.

False positives I affirmatively ruled out (do not confuse these with 6,405,047)

Web searches for the string "6405047" and for "'047 patent" return several unrelated documents that a hurried analyst could misattribute. I checked each:

1. JP 6405047 (JP6405047B2) — a Japanese patent, "リニアモータ及びその支持体" (linear motor and its support), owner Braun GmbH, registered 2018-09-21. Shares only a numeric suffix; not a U.S. patent and not this patent. Confirmed at the JPO publication PDF via Google Patents-hosted images.
2. U.S. Patent No. 7,995,047 ("current driving device" / display driver) — challenged in an IPR petition by [BOE Technology Group Co., Ltd.](/litigations/by-plaintiff/BOE%20Technology%20Group%20Co.%2C%20Ltd.) against Bishop Display Tech LLC. The petition's shorthand "'047 Patent" refers to 7,995,047, not 6,405,047.
3. IPR2025-00606 (NVIDIA Corp. v. Neural AI LLC) — a search-result fragment referencing "the '047 patent" and a Texas litigation where "PO has asserted only claim 1." That proceeding is captioned on U.S. Patent No. 8,648,867 ("System for Numerical Simulation"), and the '047-suffix reference in the surrounding brief text does not correspond to 6,405,047. NVIDIA v. Neural AI ended in a discretionary denial (institution decision 2025-07-31) and is wholly unrelated to the Moon/Samsung position-tracking patent.
4. The only genuine references to 6,405,047 I located are citation-only: it is cited by later location-related patents (Google Patents lists 88/170 "cited by" entries, heavily Qualcomm and AT&T Mobility) and it cites six prior-art references (US4649543, US5293645, US5764188, US5900838, US6108556, US6308073). Citations are not litigation and are not PTAB proceedings.

I flag these because the numeric noise around "6405047" / "'047" is unusually high, and a defendant's counsel should not cite any of the above as if it were a PTAB outcome for this patent.

Strategic summary

Claim status. Because no AIA trial has ever been instituted, the correct characterization is: claims 1–18 are all UNTESTED — none CANCELED, none SUSTAINED by any FWD. There is no narrowing through post-grant amendment, no certificate canceling claims, and no surviving-claim list to hand a defendant. Anyone representing that claims 1–5 or any other subset have been "canceled" would be fabricating a record. The patent's claims 1 and 10 are the independent device and method claims; claims 2–9 depend from claim 1 and claims 11–18 depend from claim 10, but none has been construed by the Board.

Estoppel landscape. With no petitioner, no institution, and no FWD, § 315(e)(2) estoppel is empty — no party is barred from raising any § 102 or § 103 ground on 6,405,047 in a district court or ITC proceeding. Likewise there is no § 325(d) "same or substantially the same art" history at the Board to work against a future petitioner. The only Office-side record is the original 1999–2002 prosecution (including the six cited references above), which a future challenger could still distinguish or attack on its own terms. Note also the jurisdictional gates a hypothetical petitioner faces: this is a pre-AIA patent (application filed 1999-12-01, long before the 2013-03-16 AIA cutoff), so PGR is unavailable by effective filing date and CBM is unavailable because the subject matter is not a "financial product or service." IPR would be the only vehicle — and § 315(b) would have started a one-year clock only upon service of a complaint alleging infringement, which appears never to have occurred.

Pattern signals. There is no serial-petitioner pattern (no petitioner has filed even once), no patent-owner appeal activity to the Federal Circuit, and no evidence of a defensive aggregator such as Unified Patents in the chain. Given the patent's 2019-12-01 expiration, the absence of PTAB activity is not a surprising "well-asserted patents eventually attract IPRs" anomaly — it is consistent with a patent that was never asserted in a live campaign during the IPR era (2012–2019). My prior litigation-summary finding (no known litigation) is corroborating, and it is not contradicted by anything in this PTAB review: no litigation, no IPR clock, no IPR.

Recommended next steps

• Defendant posture: If you are being threatened today, the primary response is not a PTAB argument but a "can't be infringed" argument — U.S. 6,405,047 expired 2019-12-01, so post-expiration damages are unavailable; only pre-expiration damages in an unexpired, timely-filed window would be theoretically reachable, and the patent has an early-2019 expiration with a December 1999 priority date predating virtually all LTE/5G accused functionality. Ask for the specific accused products, the accused time period, and the legal theory of post-expiration recovery.
• If a claim chart is nonetheless served: there is no FWD to link or quote — I will not invent one. The correct statement is that no AIA trial has ever been filed on this patent, so the Patent Owner's claims have never been tested at the Board. Any statement to the contrary from the asserting party is false.
• If a challenger wants PTAB coverage anyway: because the patent is expired and no § 315(b) trigger appears in the record, an IPR was (during the pre-expiration window) and remains legally available as a vehicle for the Board to review an expired patent — but the practical value is negligible absent live damages exposure. Verify status in USPTO PTAB E2E (https://e2e.uspto.gov/) and cross-check any appeal at CourtListener (https://www.courtlistener.com/) and the Federal Circuit docket before acting.
• Caveats on my confidence: PTAB's E2E/PTAB Center and the ODP API indices do occasionally lag or omit very old or administratively terminated filings. My conclusion rests on (a) the structured block in this prompt (empty) and (b) searches that surfaced no petition documents for this patent. I would treat "no PTAB activity" as well-supported but would confirm with a direct PTAB E2E patent-number query (US6405047 / application 09/453,516) before representing to a court or an adversary that none exists.

Sources used: https://patents.google.com/patent/[US6405047](/patent/US6405047)/en (patent bibliographic data, expiration 2019-12-01, citations); USPTO PTAB structured "proceedings on file" block (empty) as supplied in this prompt; ptacts.uspto.gov petition documents (reviewed and found unrelated — BOE/Bishop Display re U.S. 7,995,047; NVIDIA v. Neural AI re U.S. 8,648,867); JPO publication for JP6405047B2.

I'll research the assignment history for US 6,405,047. Let me run targeted searches.

Let me search for specific assignment records and the USPTO assignment database.

Let me try to access the Google Patents legal events and the Unified Patents page for this patent.

Assignment & Ownership Analysis — US 6,405,047 B1

Critical access caveat (read first). I attempted to query the USPTO Assignment Center (assignmentcenter.uspto.gov) and its legacy mirror (assignment.uspto.gov) directly. My tool calls hit their step limit and the search interfaces did not return machine-readable assignment records for this patent. Therefore I could not retrieve reel/frame numbers or the recording correspondent for any entry. The assignment facts below are grounded in the Google Patents legal-events record supplied as the authoritative text for this patent (https://patents.google.com/patent/US6405047/en), which reflects one assignment event — the original inventor-to-Samsung transfer — and no post-issuance assignments. Where a data point (reel/frame, correspondent) is not present in accessible sources, I say so rather than invent it.

---

Inventors

• The inventor is confirmed as Korean national Moon Yong-Moon [KR] via the WO2010069338A1 search-report citation of "US 6 405 047 B1 (MOON YONG-MOON [KR])" (https://patentimages.storage.googleapis.com/e8/d9/7d/9d78938da8996d/WO2010069338A1.pdf).
• No unusual-departure pattern determinable. The patent names a single inventor, so the "all inventors left within 12 months" fire-sale tell does not arise in a multi-inventor form. I could not verify via accessible records whether Moon departed Samsung; no departure evidence is available, so I make no claim either way.
• The application claims priority to Korean App. No. 98-52235, filed 1998-12-01 — i.e., the invention was first filed at KIPO and the US filing followed ~12 months later, a routine foreign-priority path for Samsung.

---

Original assignee

Samsung Electronics Co., Ltd. (Suwon, KR) — named as both original and current assignee in the Google Patents record.

• Line of business: Consumer electronics, semiconductors, and telecommunications network equipment — one of the world's largest makers of CDMA/GSM/5G handsets and cellular infrastructure. The patent's subject matter (mobile-station position tracking in a CDMA system) sits squarely in Samsung's core handset + RAN business.
• Product embodiment: Samsung is unambiguously an operating company in the relevant technology space, and its CDMA handsets/base stations are the class of product the claims describe. I could not, however, confirm a specific shipping product that implements the claimed tone-signal position-tracking method — this was a 1999-era IS-95/IS-95B proposal and I found no evidence it was commercialized as claimed. That is a product-embodiment uncertainty, not evidence of non-use.
• Current status: Operating (no dissolution, acquisition, or bankruptcy for the assignee entity). Note per the prior section: the patent is "Expired – Lifetime" (anticipated expiration 2019-12-01), but the assignee remains a going concern.
• Only one inventor's rights ever flowed in, and they flowed to Samsung — there is no upstream portfolio or chain preceding Samsung.

---

Assignment timeline

Chronological list of every recorded assignment I could identify. Because I could not reach the Assignment Center directly, only the single assignment event visible in the supplied Google Patents legal events is listed; no post-issuance assignments appear in any source I could reach.

• 1999-12-01 (executed; reflected at filing) / recorded 1999-12-01 — Reel/frame not captured in accessible sources
  • Conveyance: Assignment ("ASSIGNMENT OF ASSIGNORS INTEREST")
  • Assignor: Moon, Yong-Woon
  • Assignee: SAMSUNG ELECTRONICS, CO., LTD.
  • Correspondent: not retrievable — the Assignment Center record (which would name the recording attorney/firm) was inaccessible to my tools, and the Google Patents legal-events entry does not reproduce the correspondent. I flag this explicitly rather than guess.
  • Context: Original inventor assignment at filing — standard employment/obligation transfer to the employer; not a fire-sale, reorg, or third-party acquisition.

No further assignments recorded. There is no evidence of any transfer after the original inventor assignment — no security interest, merger, change of name, license, or reassignment to a licensing entity. Per the rules, this is itself a finding: the original assignee (Samsung) still owns the patent, consistent with its "Expired – Lifetime" status and with the continued listing of Samsung Electronics Co., Ltd. as current assignee.

Note on a source discrepancy (flagging, not resolving): the Unified Patents portal snippet rendered the priority date for US-6405047-B1 as 1999-11-30 (https://portal.unifiedpatents.com/patents/patent/US-[10638419](/patent/10638419)-B2), while Google Patents lists 1999-12-01. A one-day offset of this kind is typically a storage/time-zone artifact and does not change the ownership analysis, but I record it for completeness.

---

Timeline diagram

timeline
    title Ownership of US 6405047
    1998 : Korean priority application filed
    1999 : US application filed
         : Inventor Moon assigns rights to Samsung
    2002 : Patent granted to Samsung
    2019 : Patent expired Lifetime

---

NPE / troll-pattern signals

Aggregate: zero of eight NPE signals present; one indeterminate (§3) solely because the recording correspondent data was unavailable to my tools.

---

Verdict

Insufficient data — on the strict definition ("no records, or only the original assignment"), this is the only defensible selection, because the entire recorded chain consists of the single original inventor assignment (Moon → Samsung Electronics Co., Ltd., executed/recorded at filing 1999-12-01).

Justification: I found no post-issuance assignment, no transfer to any licensing entity, and no litigation in any source I could reach; the patent stayed with its original operating-company assignee (Samsung Electronics Co., Ltd.) and reached anticipated expiration on 2019-12-01 with status "Expired – Lifetime." Every concrete NPE/troll signal (shell-entity transfer, known asserter, cascading transfers, pre-litigation transfer, bankruptcy sale, privateering) is therefore not present, and the absence of any transfer is itself evidence against an NPE pattern — but I cannot elevate this to a "non-asserting" verdict because I was unable to retrieve reel/frame and correspondent data from the Assignment Center to confirm a clean single-link chain.

Verify at: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent number 6405047; legacy interface https://assignment.uspto.gov/patent/index.html). Specifically confirm (a) the reel/frame of the 1999 Moon → Samsung assignment and (b) that no later record exists, since I could not open these records directly.

I'll verify the patent record and its cited references against live sources before building the § 102 mapping.

Let me verify the remaining cited references directly.

Prior-Art Analysis — U.S. Patent No. 6,405,047 B1

Building on the earlier sections in this file (patent summary, litigation/PTAB findings, assignment history, and the § 103 obviousness analysis). This section does not re-derive the § 103 combinations — it takes the six examiner-cited references identified from the patent page and gives each one the requested treatment: full citation, publication/filing date, brief description, and the claim(s) it potentially anticipates under 35 U.S.C. § 102.

---

1. Patent identification (USPTO search — literal number match)

The only record matching the literal number 6405047 as a U.S. patent is:

Literal-number caution (carried forward from the PTAB section): the string "6405047" also returns JP6405047B2 (Braun, linear motor/shaver support) and an unrelated Solano County procurement code. Those are not this patent and are excluded. All references below are the six U.S. references printed on the face of U.S. 6,405,047.

---

2. Cited references — citations, dates, descriptions

Source-discrepancy notes (flagged, not resolved): (a) US 5,764,188 is listed with grant date 1998-06-09 on the '047 page but 1998-06-08 on the Unified Patents record — a one-day variance. (b) US 5,900,838 shows grant date 1999-05-03 (Unified Patents) vs. 1999-05-04 (Google Patents). (c) A PDF titled the same as US 5,900,838 ("…portable communication device to identify its own location") resolves to US5646632, suggesting a family/continuation relationship — treat any pinpoint cite to US 5,900,838 with that in mind. (d) I could not re-verify the disclosure text of US 4,649,543 or the bibliographic record of US 6,308,073 within this session's tool budget; the descriptions above for those two rest on the '047 record and prior search results, respectively.

---

3. § 102 analysis — which claims each reference potentially anticipates

Anticipation under § 102 requires a single reference disclosing every element of the claim, arranged as claimed. Reciting each claim's load-bearing elements (claim 1 / claim 10):

• (A) a receiver receiving tone signals from ≥ three base stations, plus base-station positional information from the service base station;
• (B) measuring phase differences dependent on propagation delay, on the basis of the base station's system reference time before propagation delay; and
• (C) a mobile-station position calculator computing position from the phase differences + the base-station positions.

Bottom line up front: none of the six references anticipates claim 1 or claim 10. Each lacks at least one element — most commonly (A)'s unmodulated "tone" signal, and (B)'s express pre-propagation-delay ("absolute system time") baseline. They are § 103 references, not § 102 anticipation references. Per-reference:

Consequence for the claim set:

• Claims 1 and 10 (independent): no § 102 anticipation by any cited reference; they stand or fall on § 103 (see prior section — Combination A: US 5,900,838 + US 5,293,645 + US 5,764,188, ± US 6,308,073).
• Claims 2–5 / 11–14 (absolute-system-time acquisition): no cited reference anticipates; even under § 103 these are the most defensible (per prior section).
• Claims 6–9 / 15–18 (controller, common control channel, transmitter structure, staggered timing): closest to anticipation but still not met by a single reference — e.g., claim 7/16's "common control channel" is effectively disclosed by US 5,900,838's sync channel, and claim 9/18's staggering is disclosed by US 5,900,838's fixed pilot offset Δ; however § 102 requires the whole claim, and each claim still carries the independent-claim tail. These are § 103 findings.

---

4. What this means (bridging to the prior § 103 section)

1. There is no single-reference anticipation case — the correct framing is a § 103 combination, exactly as developed previously (US 5,900,838 primary; US 5,293,645 + US 5,764,188 for the synchronized/absolute-time element; US 6,308,073 and/or US 6,108,556 for mobile-side computation). I am not restating those combinations here.
2. The two limitations that defeat § 102 are also the two that carry the § 103 fight: (i) "tone signals" (unmodulated CW) and (ii) measuring phase on the basis of the base station's pre-propagation-delay reference time. Every cited reference is pilot/characteristic-signal and relative-delay based, so the challenger must reach outside the cited art (e.g., the CW phase-comparison art the patent itself is classified under, G01S5/10 "omega or decca systems") to supply (i).
3. Verify before relying: confirm US 4,649,543's text (unverified here), and confirm the grant/family relationships of US 5,900,838 (vs. US 5,646,632) and US 5,764,188 before quoting them for any element.

---

5. Confidence and caveats

• High confidence on the patent's identity, its 18 claims, and the six cited references (literal match to the '047 record).
• High confidence that no cited reference anticipates claims 1 or 10 — each individually lacks the "tone signal" and/or "pre-propagation-delay absolute-time" element.
• Moderate confidence on some dates/bases (US 5,900,838 § 102(e) vs. § 102(a) treatment given its 1999-05-04 grant; US 5,764,188 and US 5,900,838 one-day date variances; US 5,900,838/US 5,646,632 family relationship).
• Lower confidence on the precise disclosure of US 4,649,543 (not re-verified) and on any pinpoint cite to US 6,308,073 (its record was not independently re-pulled in this session; description rests on the '047 record).
• This is a prior-art mapping of the six references printed on the patent, not a full validity opinion, and it does not account for art outside those citations.

Sources: https://patents.google.com/patent/[US6405047](/patent/US6405047)/en (patent record + cited references); https://patents.google.com/patent/[US5293645A](/patent/US5293645A)/en; https://portal.unifiedpatents.com/patents/patent/US-[5764188](/patent/5764188)-A; https://patents.google.com/patent/US5900838; https://portal.unifiedpatents.com/patents/patent/US-[5900838](/patent/5900838)-A; https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=[6108556A](/patent/6108556A); https://uspto.report/patent/grant/[6108556](/patent/6108556); https://patents.google.com/patent/US6308073.

I'll build the § 103 analysis on the six examiner-cited references from the Prior Art section. First, let me close the one gap that section left open (US 6,308,073 was never verified) and spot-check the two closest references.

Obviousness Analysis — U.S. 6,405,047 B1 under 35 U.S.C. § 103

Basis: the six examiner-cited references analyzed in the Prior Art section above — US 4,649,543; US 5,293,645; US 5,764,188; US 5,900,838; US 6,108,556; US 6,308,073 — plus the patent's own specification and this session's verification retrieval. All identifiers are reproduced literally.

Update to the Prior Art section (important — this changes a prior conclusion). That section recorded US 6,308,073 as "content unverified" and therefore "not assessable." I have now retrieved its disclosure. It is not a marginal reference — it is, on the face of the retrieved text, the single strongest § 103 reference against claims 1, 6, 9, and 10, because it expressly discloses (i) a remote station computing its own position from propagation delays to multiple base stations, (ii) the remote station then transmitting that position back to a base station, (iii) triangulation/intersecting spheres using known base-station locations, and (iv) base stations transmitting "substantially synchronized signals … at different points in time" (its claim 7). That last element maps directly onto claims 9/18. The prior section's "treat as incomplete" caveat should now be superseded. Sources: https://patents.google.com/patent/US6308073#1 ; https://insight.rpxcorp.com/patent/[US6308073B1](/patent/US6308073B1)

---

1. Legal framework and level of ordinary skill

• Statute. Pre-AIA § 103 applies (US app. 09/453,516, filed 1999-12-01; KR priority 98-52235, filed 1998-12-01). All six references qualify as prior art: 4,649,543 / 5,293,645 / 5,764,188 under § 102(b); 5,900,838, 6,108,556, 6,308,073 under § 102(e) as of their actual U.S. filing dates (1994 parent; 1998-01-30; 1999-03-31, respectively — note 6,308,073's 1997-07-15 foreign priority does not carry its § 102(e) date under pre-AIA law, but its 1999-03-31 U.S. filing still predates the applicant's 1999-12-01 filing).
• Standard. Graham v. John Deere (scope/content, differences, PHOSITA level, secondary considerations); KSR Int'l v. Teleflex (rationales beyond rigid TSM — "combining prior art elements according to known methods," "simple substitution," "use of known technique to improve similar devices," "obvious to try" with a finite number of predictable solutions).
• PHOSITA (proposed). A B.S. in electrical engineering (or equivalent) with 2–3 years of experience in CDMA cellular system design, including PN synchronization, propagation-delay measurement, and network-based geolocation — or an M.S. with less experience. This is the art level reflected in the references' own backgrounds.
• Claim construction notes that affect the analysis. (a) "tone signals" is defined by the spec as "a no-modulation frequency tone signal different from the channel standard of the CDMA system" — this is narrower than a CDMA pilot or a modulated waveform and is the principal gating limitation. (b) "a base station's system reference time before propagation delay" is the patent's "absolute system time" (T_bs). (c) Claim 1 preserves the granted typo "tone signals form at least three base stations" (not corrected).

---

2. The gating limitations a combination must supply

The two hardest limitations are L3 ("tone") and the claims 2–5/11–14 absolute-time derivation. Everything else is cumulative.

---

3. Combination 1 (primary) — claims 1 and 10

US 5,900,838 in view of US 5,293,645; optionally further in view of US 6,308,073.

• US 5,900,838 discloses a CDMA portable device that self-locates from ≥3 base stations, using pilot signals "offset … by integral multiples of a fixed duration" Δ, sync-channel messages that carry the base stations' geographic coordinates, a relative-delay calculation unit measuring the delay between pilot arrivals, and a mobile location unit that places the device on a selected line/hyperbola and intersects the curves — i.e., it maps L1, L2, L3 (phase/timing difference attributable to propagation), L4 (a known, fixed transmission-time baseline), and L5.
• US 5,293,645 supplies the express "triangulation" step, the known base-station locations requirement (its claims 4 and 9), and — critically — a master timing reference distributed to the base stations by direct link (its claims 3, 5, 6), which is the functional equivalent of the claimed pre-propagation-delay system reference time (L4). Its claim 14 teaches the terminal determining propagation delays "relative to the time of receipt of the timing reference signal from the designated base station."
• US 6,308,073 corroborates the architecture (remote station does the distance/position math and sends the position back to a base station) and adds the "substantially synchronized signals … at different points in time" element (its claim 7).

Motivation to combine (articulated, non-hindsight)

1. Same field, same problem, same solution family. All three address locating a mobile in a cellular network using propagation delay from multiple base stations with known locations. KSR rational (C): use of a known technique (relative-delay trilateration) to improve a similar device.
2. Express teaching in one reference pointing to the other. The US 5,900,838 specification itself identifies US 5,293,645 in its Background and criticizes it ("in order to identify the location of the radio terminal, the radio terminal must transmit information to a unit in the network that is external to the radio terminal … the user … does not have immediate access to its location") and then states the invention "does not require that the radio terminal transmit information to other units in the network." This is textbook suggestion — the reference's own words supply the reason to adopt the mobile-side computation of claim 1. Source: https://patentimages.storage.googleapis.com/be/02/6b/d596b2de133aca/[US5646632](/patent/US5646632).pdf (family text of the same title/spec; see §7 caveat).
3. Predictable result. Intersecting range circles/hyperbolae from known base coordinates is a closed-form, well-understood computation (5,293,645's own specification: "using 'triangulations' or other geographical intersection techniques"). No new result is obtained.
4. Design incentive / market force. Both the '047 specification and 5,900,838 identify the same commercial driver — avoiding GPS in the handset and avoiding burdensome reverse-link signaling.

Assessment: claims 1 and 10 are strongly obvious (high confidence) over 5,900,838 alone (single-reference § 103), and very strongly obvious over 5,900,838 + 5,293,645, if "tone signals" is given its full spec-defined scope. If "tone" is construed to exclude coded pilots, the combination needs the additional art discussed in §5.

---

4. Combination 2 — claims 2–5 and 11–14 (absolute-system-time acquisition)

Applicant's own admitted prior art (spec. Description of Related Art) + US 5,764,188 + US 5,900,838 / 6,308,073.

This is where the § 103 case is, in my view, strongest and least appreciated. The '047 specification admits the entire two-way procedure now claimed:

"The mobile station transmits a message including its PN sequence to the base station. The base station measures a propagation delay time of the message and transmits the propagation delay time information back to the mobile station. Then, the mobile station acquires a time where the propagation delay time information is received, i.e., the base station's system reference time at the present time by using the mobile station system reference time adjust amount from the message transmission time to the propagation delay time information arrival time."

That paragraph is the substance of claim 3 / claim 12 (PN-sequence message sent; delay information returned; adjust amount initialized/maintained; absolute time acquired) and of claim 2 / claim 11. Under MPEP § 2129, an applicant's admission in the specification of what was known is available as prior art for § 103. The Background likewise admits that base stations "generate a system reference time using the global positioning system (GPS)" and that the mobile "synchronizes its system reference time with the base station's system reference time" via pilot/sync channel — i.e., the common, pre-propagation reference clock (L4) is admitted prior art.

For the remaining structure, US 5,764,188 teaches a CDMA location request/response exchange: a spread-spectrum request is sent, the subscriber returns a message indicating "the receive time of a particular symbol of the base's spreading sequence and the transmit time of a particular symbol of the subscriber's spreading sequence," base stations each determine a receive time of a predetermined symbol, and the data are processed with "known base location and delay information." A POSITA combining 5,764,188's message-based delay reporting with the admitted IS-95 sync-acquisition procedure reaches claims 2–3/11–12 with predictable results.

Claims 4–5 and 13–14 — the equations

Claims 4 and 13 recite T_ms(T) − ΔΓ(T) = T_bs(T) − Γ(n); claims 5 and 14 recite the two intermediate relations Γ(T) = Γ(n) − ΔΓ(T) and T_ms(T) = T_bs(T) − Γ(T). Once the admitted prior-art procedure and the physical variables are identified — a fixed pre-propagation base-station clock, a mobile clock lagging by propagation delay, a base-measured round-trip component, and the mobile's accumulated adjust amount between transmit and receive — these are straightforward algebraic rearrangements of relationships the specification itself states as Equation (1) ("T_ms(t) = T_bs(t) − Γ(t)"). There is no unexpected result; the claim is the result of ordinary algebra on admitted relations, which is obvious as a matter of law under In re Grams / In re Richman line of reasoning (a mathematical relationship to which no non-obvious physical significance is added beyond the admitted procedure).

Assessment: claims 2–5 and 11–14 are obvious with high confidence on the applicant's own admissions, reinforced by 5,764,188. Independent of any combination, the admissions arguably support a § 102(b) anticipation theory as well; that is a stronger contention than the Prior Art section (which used only the six references) was able to make, because it did not treat the specification's admissions as prior art.

---

5. Combination 3 — the "tone signals" limitation (the crux)

This is the only element that gives the patent a plausible non-obviousness story, and it is worth being precise about which art supplies it.

(a) US 4,649,543 (of record). Discloses supervisory audio tone (SAT) — a single-frequency audio tone used for co-channel-interference control in a radiotelephone system — and control-channel message formatting. It shows a POSITA knows how to generate and detect a discrete single-frequency tone in a cellular radiotelephone. It does not use a tone for ranging. As a "tone supplier" it is weak-to-moderate; its best use is to establish the base-station tone-generation and detection context and, with ordinary RF transmitter design knowledge, to render claims 8/17 (tone generator → carrier generator → mixer → up-converter) obvious. Claims 8/17 are obvious with high confidence: that four-element transmit chain is the canonical architecture of any RF exciter, and the claim recites no unusual interaction among the elements.

(b) Common knowledge / the prior art's own framing. US 5,900,838's Background expressly acknowledges "Loran-C receivers … use a radio pulsed navigation system" as a known radio-positioning technique, and discusses why GPS is unsuitable indoors — establishing that radio-navigation by measuring received timing/phase of broadcast signals is ancient and well-known. The '047 patent is itself classified by the Office in G01S 5/10 — "Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements, e.g. omega or decca systems" — classification art in which phase comparison of continuous-wave tones is the defining method. A POSITA asked to build a phase-difference ranging receiver who needs a waveform whose phase is directly measurable at the receiver would readily select an unmodulated single tone over a coded pilot, because the tone is the phase reference; the motivation is that a CW tone eliminates the despreading/correlation step and yields a directly measurable phase. This supports a "simple substitution of one known element for another" rationale (pilot → CW tone) with predictable results.

(c) Supplementary art disclosed in this session but NOT of record — flag this. US 5,883,598 (Part et al., Signatron Technology Corp.) states: "In one embodiment, the locating signal comprises two or more single-frequency tones … The tones can be transmitted at different times, or, in an alternative embodiment, they can be transmitted simultaneously," and "Because … only single-frequency tones are used as the locating signal … substantial transmission circuitry is eliminated." Filed 1995-12-15, granted 1999-03-16, it would qualify under pre-AIA § 102(e) as of its 1995 filing date. This reference directly supplies the "tone signals … transmitted at different times" limitation and would, combined with 5,900,838/5,293,645/6,308,073, make claims 1, 9, 10 and 18 difficult to sustain. Caveat: it is not among the examiner-cited six, I have not verified its full claim set element-by-element, and its use requires an independent § 102(e) date verification. I flag it as the single highest-value additional reference to pull.

Assessment: the tone limitation is obvious at moderate confidence on the record art (5,900,838's Loran-C teaching + Decca/Omega classification + 4,649,543's SAT context), and obvious at high confidence if US 5,883,598 is added.

---

6. Combination 4 — claims 6–7 and 15–16 (single-tone list message over a common control channel)

US 5,900,838 + US 6,308,073 (+ US 4,649,543 for common-channel messaging).

• US 5,900,838 discloses base-station geographic location carried in sync-channel messages — a broadcast channel received by all mobiles, i.e., not a point-to-point traffic-channel message. Substituting the IS-95A paging channel (the '047 spec's own example) for the sync channel is a simple design choice among common control channels.
• US 6,308,073's background expressly contemplates the mobile receiving the delay/position data and sending an "assist request" message with the computed distances to the base station(s) — the "transmitting the calculated mobile station's positional information to the service base station" element of claims 6/15.
• The claimed list contents (tone period, base ID, base position, tone frequency) are each individually conventional system-parameter broadcasts; aggregating them into one message is a predictable arrangement of known information elements (KSR).

Assessment: claims 6–7/15–16 obvious, moderate-to-high confidence. Note the '047 spec admits the list "is not a message for a specific mobile station" and must go on a "control channel used in common by every mobile station. For example, a paging channel corresponds to that channel in the IS-95A system" — again the applicant's own admission.

---

7. Combination 5 — claims 9 and 18 (periodic transmission at different time points)

US 6,308,073 (claim 7) + US 5,900,838 (staggered pilot Δ).

• US 6,308,073, claim 7: "transmitting substantially synchronized signals from said at least three base stations to said mobile station at different points in time." This is the claim's structural core.
• US 5,900,838: pilots of one base are "offset in time by integral multiples of a fixed duration" where "the time offset allows the pilot signals of one base station to be distinguished from those of other base stations" — an express reason to stagger transmissions.
• Motivation is therefore supplied by the art itself, not by the patent's own "prevent inter-modulation" rationale (which would otherwise be hindsight): distinguishing multiple co-channel transmissions and avoiding collision/overlap is the stated purpose in 5,900,838, and 6,308,073's own spec uses guard times "to minimize the possibility of received and transmitted signals overlapping in time due to the varying transmission distances."

Assessment: claims 9/18 obvious, moderate-to-high confidence — the only gap is again the word "tone," supplied per §5.

---

8. Claim-by-claim § 103 summary

---

9. Where the patent can still be defended

1. "Tone signals" as a construed limitation. If a court/Board construes "tone signal" per the spec ("no-modulation frequency tone signal different from the channel standard") and holds that a CDMA pilot, spreading-sequence symbol, or "timing reference signal" is not a tone, then the single-reference theories over 5,900,838 / 5,293,645 / 6,308,073 each fail on L3, and the § 103 case depends on the tone-supplying step in §5 — which on the cited record is the weakest link. This is the patent's best argument.
2. Measurement "on the basis of the base station's system reference time before propagation delay." US 5,293,645 measures relative to a designated base station's received signal (a relative, not absolute, reference); 5,900,838 estimates the transmission-time offset Δ by rounding to the nearest multiple of the stagger. Applicant could argue neither discloses measuring against the base's absolute clock, only against relative baselines. Counter: the mobile's own admitted IS-95 sync acquisition (independently disclosed in the Background) provides the GPS-derived absolute reference, so the combination yields it; and 5,293,645's master timing reference is a functional absolute reference.
3. The specific two-way equation (claims 4–5). Applicant could argue the particular composition — base-measured Γ(n) of the mobile's PN message combined with the mobile's elapsed adjust amount ΔΓ(T) to reconstruct T_bs(T) — is not shown in any single reference. Counter: it is the admitted procedure plus algebra; and 5,764,188 shows the two-way symbol-timing exchange.
4. Secondary considerations. I found no evidence of commercial success, long-felt need met, industry praise, or copying tied to the claims, and no litigation (per the prior Litigation and PTAB sections). The patent expired 2019-12-01 ("Expired – Lifetime"), which undercuts any nexus-based objective-indicia argument in a current proceeding. No secondary consideration currently rebuts the prima facie case.

Hindsight guard: the motivation to transmit tone signals "at different time points" must be sourced from 5,900,838's express "distinguish" rationale and 6,308,073's claim 7 — not from the '047 spec's own "prevent inter-modulation" sentence. Similarly, the "avoid reverse-link interference" motivation appears in 5,293,645's Background (criticizing McCaughan/GB 2,215,932 for "increas[ing] the messaging load") and is therefore independently available in the art.

---

10. Confidence, corrections, and open items

• Correction to the Prior Art section: US 6,308,073 is assessable and is strong against claims 1, 6, 9, 10 (see §3, §6, §7). The prior "do not rely on this entry" instruction should be withdrawn. Its § 102(e) date is its U.S. filing date of 1999-03-31, not the 1997-07-15 foreign priority (pre-AIA § 102(e) does not extend to foreign priority) — still prior art to the 1999-12-01 filing, but the margin is ~8 months, worth verifying in the file wrapper.
• Apparent family overlap for the closest reference (flagged, needs verification): the retrieved text of US 5,900,838-titled subject matter appears in a document imaged as US 5,646,632, bearing the identical title "Method and apparatus for a portable communication device to identify its own location." If US 5,646,632 is a genuine earlier sibling in the same family, it would be § 102(b) art in its own right with the same disclosure and an earlier grant date. I have not independently confirmed the family relationship and record it as an open item rather than a finding. Source: https://patentimages.storage.googleapis.com/be/02/6b/d596b2de133aca/US5646632.pdf
• Unresolved bibliographic discrepancies carried forward (from the Prior Art section, unchanged): US 5,764,188 (filed 1995-05-08 vs 1995-05-07; granted 1998-06-09 vs 1998-06-08) and US 5,900,838 (priority 1994-11-14 vs 1994-11-13; app. date 1997-07-06 vs grant 1999-05-03 vs 1999-05-04). None changes the § 102 category or the § 103 analysis.
• I did not review the original office action, so I cannot state which of the six references the examiner applied under § 102 versus cited as background. Verify in USPTO PatentCenter for application 09/453,516 before relying on any statement about the prosecution history.
• US 5,883,598 is supplementary art not of record, surfaced in this session's retrieval. Treat its inclusion as a lead requiring confirmation (claims, § 102(e) date, and element-by-element mapping), not as an established ground.
• No PTAB or litigation record was manufactured here. As established in the prior sections, zero AIA proceedings and no known litigation name this patent; claims 1–18 remain untested. Nothing in this § 103 analysis is a substitute for a claim chart or a legal conclusion, and no proceeding number is invented or implied.

Bottom line: the independent claims (1/10) are obvious with high confidence over US 5,900,838, expressly combined with US 5,293,645 and/or US 6,308,073, on KSR rationales that the references themselves state. The dependent claims fail either on the applicant's own specification admissions (claims 2–5/11–14) or on ordinary predictability (claims 6–9/15–18). The single point of genuine resistance is the "tone signal" limitation, which on the cited record is only circumstantially met; a challenger who adds art expressly disclosing single-frequency tone transmissions (e.g., US 5,883,598) converts that resistance into the patent's weakest link.

Sources: https://patents.google.com/patent/[US6405047](/patent/US6405047)/en (patent text, admissions, claims, classifications, expiration); https://patents.google.com/patent/US6308073#1 and https://insight.rpxcorp.com/patent/US6308073B1 (US 6,308,073 disclosure and claims); https://patents.google.com/patent/US5900838 and https://patentimages.storage.googleapis.com/be/02/6b/d596b2de133aca/US5646632.pdf (US 5,900,838 specification and its express treatment of US 5,293,645; apparent sibling US 5,646,632); https://www.everypatent.com/comp/pat5293645.html and https://patents.google.com/patent/[US5293645A](/patent/US5293645A)/en (US 5,293,645 claims, master timing reference, triangulation, McCaughan background); https://patentimages.storage.googleapis.com/6f/7c/6f/e3d147ac8f5ef9/US5883598.pdf (US 5,883,598 — supplementary).