US 5054035

I'll search for authoritative records on this specific patent number.

Now let me check for litigation and CAFC docket activity.

US Patent 5,054,035 — Analyst Summary

Sources consulted: Google Patents (US5054035A, full text fetched 2026-09-24), uspto.report/patent/grant/5054035, EPO Global Patent Index entries citing US5054035A, plus targeted searches of USPTO and CAFC-facing sources. Note: I interpreted the identifier literally as 5054035 / US5054035A / US 5,054,035, and did not substitute any similar number.

1. Bibliographic Data

Prior art cited on the face (6): US 3,699,261 (Nippon Electric); US 4,596,981 (Victor Company of Japan); US 4,697,473 (Oki Electric); US 4,807,248 (Rockwell); US 4,807,261 (Motorola); US 4,899,383 (Westinghouse). Separately discussed in the specification background: US 4,308,429 (Kai et al.) and US 4,829,519 (Scotton et al.). The patent has a substantial forward-citation record (Google Patents lists 38 "cited by" entries in one table and 74 in another, including Motorola US 5,386,495 and Qualcomm US 5,802,105), and US5054035A appears as an "A" category reference in the search reports of GB 2 309 859 A, EP 0 788 242 A1, EP 1 732 258 A4, and EP 1 780 928 A1.

2. Abstract (as issued)

In evaluating the quality of received digital signals in terminals of a mobile communication system, the bit error rate is measured. Each station receives signals in successive data frames which includes a synchronization pattern and stores a version of the synchronization pattern. The received synchronization pattern is compared to the stored synchronization pattern to derive a signal representative of the received signal quality. The quality signal may then be used for hand-off to other base stations or other call transfers. Since the synchronization pattern is included in each data frame, measuring signal quality therefrom obviates the need for system generation and interpretation of special quality messages.

3. Plain-Language Overview of Each Independent Claim

Claim 1 — Apparatus ("A terminal for a mobile radio communication system comprising…")

A receiver in a mobile/cellular terminal that judges channel quality from the frame sync pattern itself, rather than from special test messages. In plain terms, the terminal:

1. Receives a digital signal (e.g., a cellular radio channel).
2. Generates a symbol sequence arranged in time frames, each frame carrying both information symbols and a prescribed set of synchronization symbols. (The specification gives example patterns: binary 1111100101000, or, for quaternary differential PSK, 0, π/4, π/2, −3π/4, 0, −3π/4, π/2, π/4, 0, π/4, π/2, −3π/4.)
3. Stores a reference copy of the expected sync symbols in a first shift register.
4. Compares the received sync symbols against the stored reference across a plurality of frames to produce a "differences" signal. The claimed comparison hardware is specific:
   • a second shift register that serially accumulates the incoming sync symbols;
   • a third shift register;
   • timing means that identifies which symbol periods in each frame correspond to the sync pattern;
   • transfer means (located between the second and third registers) that, on the identifying signal, moves the received sync symbols from the second into the third register;
   • mismatch detection between each position of the first (reference) register and the counterpart position of the third (received) register, within the identified symbol period;
   • an error signal per detected mismatch.
5. Forms a quality signal for the received digital signal from the accumulated differences.

Structurally, this maps onto FIG. 3 of the patent: shift register 301 (received symbols), register 305 (transferred received sync symbols), register 310 (prestored reference pattern), exclusive-OR gate 330 with AND gate 340 producing error pulses EEO, and flip-flop 320/inverter 335 generating the compare clock from signal TRIG.

Claim 3 — Method (independent, mirrors Claim 1)

The method counterpart of Claim 1, covering the same subject matter as steps performed in a mobile radio terminal:

• receiving the digital signal;
• generating the framed symbol sequence including the prescribed sync symbols;
• storing the reference sync pattern in a first shift register;
• generating a differences signal across multiple frames by (i) sequentially storing received sync symbols in a second shift register, (ii) generating a symbol-period identifying signal, (iii) transferring the second register's contents to a third shift register in response to that signal, (iv) detecting mismatches position-by-position against the first register in the identified symbol period, and (v) generating an error signal per mismatch;
• forming a quality-representative signal from the differences signal.

4. Dependent Claims (for completeness)

• Claim 2 (depends on Claim 1) adds the measurement-period machinery: means that set a prescribed signal evaluation period upon a predetermined number of symbol-period identifying signals; means producing a signal quality threshold; means generating a symbol error rate (SER/BER) signal over each evaluation period from the error signals; and means forming a quality signal from the SER signal compared against the threshold.
• Claim 4 (depends on Claim 3) is the method analogue of Claim 2.

Supporting disclosure for these dependent claims is found in FIGS. 2, 6 and 7 and the described components: synchronization pattern error detector 201, error counter 205, symbol counter 210 (frame-end pulse CO1), error period counter 215 (end-of-period pulse CO2), OR gates 220/225/230, clock 250, and signal quality processor 150 (described as an Intel 8051-type microcontroller with I/O 501, data memory 505, processor 510, program memory 515, bus 520). The FIG. 6 flow (steps 601–640) covers acquisition using threshold THSE and a sync-found index L compared to constant K (e.g., 10) for K successive frames; the FIG. 7 flow (steps 701–770) covers per-frame error threshold THFE, frame-error index t versus value T producing loss-of-synchronization signal LOS, accumulation to a BER signal, comparison to threshold THBER, and emission of a channel report signal (CRS/CCR) for channel change or handoff.

5. Litigation / CAFC Docket Findings — Important Caveat

I searched specifically for litigation or Federal Circuit docket activity tied to 5054035 / 5,054,035. My searches returned no authoritative litigation or CAFC docket records for this patent number. I therefore cannot confirm the existence of any suit, IPR/PGR, or appeal involving it — and equally cannot assert with confidence that none exists, because my searches were web-index based rather than a direct query of PACER, the CAFC docket system, or Docket Navigator.

What I can confirm from the record: the patent's only tracked post-grant legal events are maintenance-fee administrative events leading to lapse effective 2003-10-01 (37 CFR 1.362), with no assignment or reissue events of record beyond the original 1989 assignment to Bell Telephone Laboratories, Inc. and American Telephone and Telegraph Company.

6. Points of Uncertainty / Minor Observations

• Assignee chain: Google Patents lists current assignees "Nokia Bell Labs USA" and "AT&T Inc." while the recorded original assignee is AT&T Bell Laboratories Inc. Google Patents itself cautions its assignee lists "may be inaccurate," and I found no intervening recorded assignment document. Treat the current-owner listing as indicative, not authoritative.
• Forward-citation count discrepancy: the same Google Patents page shows both a 38-entry and a 74-entry "Cited By" table (the larger includes family members and examiner/third-party distinctions). Which is the official count is unclear to me.
• Terminology inconsistency in the specification: the text refers to a "signal quality report signal CCR" in the description of FIG. 5 but to a "channel report signal CRS" in the FIG. 7 discussion (step 765). These appear to denote the same output, but the patent uses two different labels.
• Terminal-status aside: the patent expired for non-payment of maintenance fees in 2003, so it is not in force as of today's date (April 26, 2026) — any current analysis of it is historical/informational only.
• The Canadian sibling CA2023715C (granted 1995-01-17) carries the same title and inventors and represents the same invention.

If you need a definitive litigation check, that would require a direct PACER/CAFC docket query or a commercial litigation database, which I cannot access here.

I'll search for litigation involving US patent 5054035.

Let me search more targeted sources.

The initial searches returned unrelated '035 patents. Let me search patent-specific litigation databases.

Litigation Search Results for U.S. Patent No. 5,054,035

Bottom line: I found no litigation involving U.S. Patent No. 5,054,035.

Despite searching patent-litigation aggregators (Unified Patents portal, CourtListener/RECAP, PACER-derived documents, PTAB filings) and general web sources, I could not identify any case — district court, ITC, PTAB, or CAFC — in which U.S. Patent No. 5,054,035 was asserted, challenged, or otherwise at issue.

Why the search produced no hits (and how to interpret that)

• Short-shorthand collisions. Many litigation documents refer to an asserted patent as "the '035 Patent." Every such hit I reviewed involved a different patent whose number merely ends in "035" (e.g., patents asserted in HP v. Wilus and in the Pantech v. OnePlus action). Per the strict rule, I did not treat those as U.S. 5,054,035. None of those short-hand references can be confirmed to correspond to 5,054,035, and the technical subject matter (later-generation cellular/WLAN patents) is inconsistent with this 1989-era patent.
• No PTAB activity surfaced. No IPR/PGR/CBM petition referencing 5,054,035 appeared in the USPTO PTAB results.
• Prosecution/provenance context. U.S. 5,054,035 ("Digital signal quality evaluation circuit using synchronization patterns," inventors Tarallo and Zysman) was filed 1989-12-21, granted 1991-10-01, and originally assigned to AT&T Bell Laboratories / American Telephone and Telegraph Company. Its recorded legal events show only maintenance-fee activity; it expired for failure to pay maintenance fees with an effective date of 2003-10-01 (maintenance-fee reminder mailed 2003-04-16; lapse notices 2003-10-01 and 2003-10-29). Google Patents lists current assignees as Nokia Bell Labs USA and AT&T Inc., and the status as "Expired – Fee Related." There is no indication in these records of any litigation transfer or assertion campaign, which reduces (but does not eliminate) the likelihood of a later enforcement suit.

Case table

Caveats on completeness

I must be explicit about the limits of this answer rather than overstate confidence:

1. My searches relied on publicly indexed sources. Some pre-1990s and low-profile suits — and cases that settled or were dismissed very early — may not appear in free aggregators such as the Unified Patents litigation portal or CourtListener RECAP, which depend on coverage of PACER dockets.
2. Defense-side declaratory-judgment actions, counterclaims, and unindexed state-court actions could exist without surfacing in keyword searches.
3. To achieve a truly definitive "no litigation" conclusion, a paid docket service (Docket Navigator, Lex Machina, or RPX Insight) and a full PACER party-name search on "Tarallo," "Zysman," and the original assignees would be the appropriate next step. I could not complete those paid searches here.

If you can tell me a likely asserting party or time frame (for example, a post-2000 patent-assertion entity that may have acquired the patent), I can run a narrower follow-up search on that party.

Proceedings overview

Total AIA trial proceedings on file for U.S. Patent No. 5,054,035: zero (0). Breakdown of status categories — active: 0; claims invalidated: 0; claims sustained: 0; settled: 0; institution denied: 0. The structured "PTAB proceedings on file" block (USPTO Open Data Portal) returns no IPR, PGR, or CBM proceedings, and my independent web searches surfaced no AIA trial referencing this patent. The defensive posture is therefore unusual but not "hardened": the patent is untested before the PTAB because it expired on 2003-10-01 for failure to pay maintenance fees — before the AIA trial regime existed. There is no FWD to point to and no claim that has been canceled or confirmed. A defendant today cannot rely on a PTAB win; any invalidity case must be built from scratch (district court, ITC, or an ex parte reexam/reissue-style avenue), and the expired status is itself the dominant fact.

Proceedings

None — no AIA trial proceeding has ever been filed on U.S. Patent No. 5,054,035

• Type: N/A (no Inter Partes Review, Post-Grant Review, or Covered Business Method Review on file).
• Filed: N/A.
• Status: N/A — the USPTO ODP-derived structured block reports no proceedings; no petition, institution decision, or FWD referencing 5,054,035 appears in public indexes. Verbatim from the structured data: "The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest."
• Judge panel: N/A.
• Petition grounds: N/A — no petition exists to state grounds for.
• Institution decision: N/A.
• Final Written Decision: N/A. Note also the parity point: because there is no FWD, no claim of this patent has been adjudicated unpatentable or patentable by the Board — I will not imply otherwise.
• Settlement / termination: N/A.
• Appeal: N/A — no FWD to appeal to the Federal Circuit.
• Defensive value: Low-to-zero as an estoppel asset, but the absence is explained by the patent's own lifecycle (see below), not by the patent surviving attack. Do not argue to a court that "the patent has survived PTAB scrutiny" — there has been no scrutiny. Conversely, do not assume the absence of IPRs means the claims are strong.

Why no AIA trial exists (structural, not incidental)

Three independent reasons, each grounded in the record:

1. Expiration before the AIA trial regime. Google Patents' legal-events table shows a maintenance-fee reminder mailed 2003-04-16, lapse notices dated 2003-10-01 and 2003-10-29, and an effective lapse date of 2003-10-01 ("PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES"). The AIA trial provisions took effect 2012-09-16. No rational petitioner files an IPR against an expired patent whose claims can no longer be enforced — there is no infringement exposure to defend against and no injunctive/damages benefit to seek.
2. PGR ineligibility. Post-Grant Review under 35 U.S.C. § 321 is available only for patents with an effective filing date on or after 2013-03-16. This patent's priority date is 1989-12-21 and it was granted 1991-10-01 — categorically outside PGR eligibility.
3. CBM program sunset. Covered Business Method review applied only to covered business method patents and, in any event, the program's statutory window closed on 2020-09-16. Even had a petitioner tried, the window has closed.

Strategic summary

Claim status: entirely UNTESTED, and unenforceable-by-age if the lapse stands. All four claims — claim 1 (terminal apparatus, the sole independent apparatus claim), claim 2 (dependent, error-period/threshold evaluation), claim 3 (independent method claim mirroring claim 1), and claim 4 (dependent method claim mirroring claim 2) — are as issued. No claim has been canceled, disclaimed, or narrowed by any PTAB proceeding. There are no "surviving claims" in the IPR sense, because there was never a proceeding from which claims needed to survive. The narrowing, if any, comes from prosecution history and from the Federal Circuit/SCOTUS § 101 caselaw developed decades after grant — not from the Board.

Estoppel landscape: nothing to work with. 35 U.S.C. § 315(e)(2) estoppel attaches only to a petitioner that obtained an FWD. With no petitioner and no FWD, no § 315(e)(2) estoppel exists against anyone, and there is no "ground that was raised or reasonably could have been raised" bar. That cuts both ways: a defendant has every prior-art ground open to it (the six examiner-cited references — US 3,699,261; US 4,596,981; US 4,694,473; US 4,807,248; US 4,807,261; US 4,899,383 — plus anything else), but it also has no pre-packaged, tested invalidity theory handed to it. Note the "cited by examiner" vs. "cited by third party" distinction in the Google Patents tables: those six references are examiner citations, which matters for § 325(d) had there been a proceeding, but § 325(d) is inapplicable with no ongoing trial.

Pattern signals: no litigation-and-IPR cycle, no aggregator, no serial petitioner. There is no repeat-petitioner pattern (no petitioner at all), no patent-owner appeal practice (nothing to appeal), and no indication of a defensive aggregator such as Unified Patents anywhere in the chain — consistent with the prior "Litigation summary" section, which identified no litigation and flagged the assignee history as AT&T Bell Laboratories → current listings of Nokia Bell Labs USA / AT&T Inc. This is the signature of a patent that simply aged out of its enforcement life, not one that was attacked and held up. One caveat on the "cited by" lists: documents like US 5,802,105 (Qualcomm, "Method and apparatus for testing a digital communication channel") and US 5,389,495 (Motorola, "Method and apparatus for determining the signal quality of a digital signal") appear only as citing references — later patents citing this disclosure as background. A citation in another patent's specification is not a validity challenge and creates no PTAB record. Similarly, the UK search report for GB 2 309 859 (Nokia) lists "US 5 054 035 (AT&T) — Whole document" as category "A" (technological background), which is a foreign-office citation, not a PTAB ground.

Contradiction check: none. The task prompt's default ("no PTAB activity on file") is consistent with the structured block and with every web result I reviewed. I found no older or recently-filed proceeding that the ODP ingest might have missed. The '035 short-hand collisions identified in the litigation section (different patents ending in "035") also reappeared in my PTAB searches — I did not treat any of those as this patent.

Recommended next steps

1. If you are a defendant facing assertion: the PTAB is not your forum, and the threshold question is whether the patent is even live. The patent expired 2003-10-01 for non-payment of maintenance fees (37 C.F.R. § 1.362 entry, "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES"), with the last maintenance fee paid for the 8-year period as of the 1999-03-29 FPAY entry. Ask the asserting party directly for (a) proof of revival or reinstatement of the patent, and (b) the assignment chain from AT&T Bell Laboratories to whatever entity is now demanding payment. An assertion premised on an expired patent, or by an entity without a recorded chain of title, is a fast Rule 11 / standing problem.
2. If the patent has somehow been revived and asserted, build the invalidity case outside the Board. Because there is no FWD to lean on, the efficient paths are (i) district-court § 102/§ 103 invalidity using the examiner-cited art above plus the enormous intervening 1990–2000 cellular digital-art corpus, (ii) a § 101 challenge — claims 1 and 3 recite generic shift registers, an XOR comparator, and a quality signal, which is exactly the "compare one thing to another" fact pattern courts have repeatedly invalidated post-Alice (compare the Blue Spike / ChargePoint line of authority), or (iii) an ex parte reexamination, which by current practice (see RPX's Q1 2026 report noting reexam filings up 190% year-over-year as IPR access tightens) is not subject to discretionary denial. Ex parte reexam is available for expired patents and does not require the patent to be enforceable.
3. Do not wait for an IPR deadline that will never arrive. There are no PTAB milestones to track — no institution-decision deadline, no oral hearing, no statutory one-year FWD date under § 316(a)(11). Anyone telling you to "calendar the FWD" is working from a template that does not fit this patent.
4. Verify the lapse independently before relying on it. The expiration is a Google Patents / USPTO legal-events assertion, and the site's own disclaimer states that legal status is "an assumption and is not a legal conclusion." Confirm via USPTO Patent Center (https://patentcenter.uspto.gov) on application 07/454,487, and check whether any petition to revive or accept an unintentionally delayed payment was ever granted.
5. If you have a specific adversary in mind — a patent-assertion entity that may have acquired the AT&T/Nokia Bell Labs rights — name it and I can run a narrower search on that entity's PTAB and district-court campaigns. That is the one factual gap I could not close with free sources.

Caveats, stated plainly: my conclusion is "no PTAB proceedings identified," based on the structured ODP block plus public web sources. I could not query a paid docket/analytics service (Lex Machina, Docket Navigator, RPX Insight) or run a full PACER/PTAB E2E party-name sweep on "Tarallo" and "Zysman." PTAB E2E (https://ptacts.uspto.gov) and the PTAB Decisions page at USPTO are the authoritative places to run that final confirmation yourself. I have not fabricated any proceeding numbers, panels, or decisions, and I have not claimed that any claim of this patent was adjudicated by the Board.

I'll verify the assignment record against live sources before reconstructing the chain.

USPTO Assignment Chain Reconstruction — US 5,054,035

Scope note on evidence. I could not execute a direct, authenticated query against the USPTO Assignment Center (assignmentcenter.uspto.gov requires session-based interaction that my web-index searches could not reach). What follows is built from the assignment data of record as it appears in the patent's legal-events table (Google Patents, fetched 2026-09-24), which is derived from USPTO assignment recordation data, plus uspto.report and EPO/Global Patent Index family entries. Where a field is not present in the surfaced record, I say so rather than filling it in. Verification link: https://assignmentcenter.uspto.gov/ (search patent number 5054035; legacy: https://assignment.uspto.gov/patent/index.html).

Headline finding: the record contains exactly one assignment, executed pre-issuance in December 1989 by the two inventors in favor of their employer. There is no post-issuance transfer of any kind — no security agreement, merger, change of name, or later assignment. At roughly 37 years of age and lapsed since 2003, this patent's ownership history is effectively frozen at its 1989 origin.

Inventors

Pattern notes. No unusual inventor-side pattern is detectable here. Specifically:

• There is no evidence of inventor departure within 12 months of filing — and equally, no evidence they stayed. The assignment record does not track employment, and I found no personnel records in the indexed sources. I am not asserting either way.
• The decisive point is structural rather than behavioral: both inventors assigned to two AT&T-family entities jointly, which is the standard instrument for the AT&T / Bell Laboratories ownership structure of that era. There is no individually-held residual interest, no assignment to a third party, and no later inventor-to-entity transfer. This is the profile of an ordinary employer-obligation assignment, not a pre-fire-sale pattern.

Original assignee

The patent names AT&T Bell Laboratories Inc. as original assignee (Google Patents front-page field). The recorded instrument itself — reel 005204/0831, recorded 1989-12-21 — names two assignees:

1. Bell Telephone Laboratories, Incorporated (New Jersey)
2. American Telephone and Telegraph Company (New York)

with the stated consideration being "ASSIGNMENT OF ASSIGNORS INTEREST; ASSIGNORS: TARALLO, JOSEPH A.; ZYSMAN, GEORGE I." (REEL/FRAME 005204/0831).

• Line of business: AT&T Bell Laboratories was the central research and development arm of the Bell System / AT&T — a research organization, not a product-shipping entity.
• Did they ship a product embodying the claims? Not directly, and not as a discrete product. The claimed subject matter is a receiver-side circuit — a sync-pattern error detector plus a quality processor built around an Intel 8051-type microcontroller (FIG. 5, elements 501/505/510/515/520) — disclosed for use in mobile cellular terminals and cell-site terminals. There is no evidence this specific circuit was ever commercialized as a standalone article of commerce; it is consistent with AT&T's internal cellular R&D during the AMPS-to-digital (TDMA) transition. I cannot confirm any specific product implementation, and I won't assert one.
• Current status of the original assignee: dissolved as a legal entity through corporate reorganization. AT&T Bell Laboratories was split in the 1996 AT&T restructuring: the bulk of Bell Laboratories went with the spun-off systems business into Lucent Technologies (spin-off effective 1996-09-30), while AT&T retained AT&T Laboratories. Lucent merged with Alcatel in 2006 to form Alcatel-Lucent, which Nokia acquired in 2016, giving rise to the Nokia Bell Labs name.
  • Critically, none of that reorganization is reflected in any assignment recorded against US 5,054,035. See the flag below.

Assignment timeline

The record contains a single entry.

• 1989-12-15 → 1989-12-18 (executed) / recorded 1989-12-21 — Reel 005204 / 0831
  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Joseph A. Tarallo (execution date range 1989-12-15 to 1989-12-18); George I. Zysman (same range)
  • Assignee: Bell Telephone Laboratories, Incorporated (New Jersey) and American Telephone and Telegraph Company (New York) — joint assignees
  • Correspondent: Not surfaced in the available record. The legal-events entry for reel 005204/0831 states only the assignors, assignee names, reel/frame (005204/0831), and signing dates. The correspondent of record — the attorney or agent who filed the recording — is not exposed in the sources I could reach. Because there is only one link in this chain, the "repeat correspondent" tell cannot be tested even in principle; see signal 3 below. I am not naming a correspondent, because doing so would require fabrication.
  • Context: Original employer assignment — the two inventors conveying their rights to their corporate employer/co-owner as a condition of employment, filed contemporaneously with the application on 1989-12-21. Not an acquisition, not a fire-sale, not a securitization, not a transfer-to-asserter.

No other recorded assignments exist. For completeness, the remainder of the patent's tracked legal events are administrative only:

Per the task instruction: because no post-issuance assignment exists, the operative finding is that the original assignee remained the owner of record for the entire enforceable life of the patent, and the patent was then simply abandoned by non-payment.

⚠️ Contradiction flag — treat Google's "current assignee" field as a data artifact, not an ownership fact

Google Patents lists the current assignee as "Nokia Bell Labs USA" and "AT&T Inc." This is not supported by any reel/frame on this patent. The prior summary section of this analysis already flagged this listing as "indicative, not authoritative," and I am now strengthening that call: it is an entity-name-resolution artifact, produced by mapping the historical name "AT&T Bell Laboratories" onto the two modern corporate descendants of that name (Nokia Bell Labs, via Lucent → Alcatel-Lucent → Nokia; and AT&T Inc., via the AT&T lineage). An analyst who reads that field as a chain and then goes looking for a Nokia/Alcatel-Lucent assignment reel will find nothing, because none exists for this patent.

To be explicit about a trap I encountered and deliberately did not step into: my searches surfaced genuine Nokia-of-America / Alcatel-Lucent assignment recordations — reel 033949/0531 (release by secured party, Credit Suisse AG → Alcatel-Lucent USA Inc., correspondent Kirkland & Ellis LLP, recorded 2014-10-09), reel 047965/0184 (assignment of assignors' interest, recorded 2019-01-11, correspondent Botos Churchill IP Law LLP), and reel 048066/0035 (change of name, Nokia of America Corporation, 2019). Those appear in an unrelated PTAB petition exhibit covering an Alcatel-Lucent portfolio. None of them names US 5,054,035, and none should be cited as part of this chain.

Timeline diagram

timeline
    title Ownership of US 5054035
    1989 : Inventors execute assignment Dec 15 to Dec 18
         : Recorded 1989-12-21 at reel 005204 frame 0831
         : Assignees are Bell Telephone Labs and ATT
         : Application filed the same day
    1991 : Patent issues on 1991-10-01
    1996 : Bell Labs splits off with Lucent - context
    2003 : Patent lapses for unpaid maintenance fee
    2026 : Still no further assignment of record

NPE / troll-pattern signals

The controlling fact for every signal below is that there is exactly one recorded assignment, dated December 1989, from two individual inventors to two AT&T-family corporate entities. No later instrument exists to analyze.

Signal I would add: stale-bibliography false positive (present)

Not on your list, but worth logging because it is the single most likely source of analyst error on this patent: the Google Patents "current assignee" field shows Nokia Bell Labs USA / AT&T Inc. with no corroborating reel/frame. A naive pipeline that trusts this field would generate a phantom Lucent/Alcatel-Lucent/Nokia ownership story and then search for a Nokia assignment reel that does not exist. Call it present as a data artifact, with the mitigating fact that the same source annotates its assignee list as potentially inaccurate. I flag it as a bibliographic hazard, not an ownership signal.

Verdict

Insufficient data — no records beyond the original assignment.

Justification. The complete post-1989 assignment record for US 5,054,035 is empty. The only recorded instrument is reel 005204/0831, recorded 1989-12-21, in which inventors Tarallo and Zysman (signing 1989-12-15 to 1989-12-18) assigned their rights to Bell Telephone Laboratories, Incorporated and American Telephone and Telegraph Company — a plain employer-obligation assignment filed alongside the application. Every downstream NPE tell is therefore not merely weak but structurally unavailable: there is no LLC, no security interest, no merger, no secondary chain, and no correspondent recurrence to test (the correspondent on the sole record is not even exposed in the available sources, and I have declined to name one). The Nokia Bell Labs / AT&T Inc. entries in Google's current-assignee field carry no reel/frame and are best explained as entity-name-resolution artifacts, not as evidence of a later transfer — and the patent itself has been dead since it lapsed for non-payment effective 2003-10-01, which closes any assertion window irrespective of ownership.

Verify at: https://assignmentcenter.uspto.gov/ — search patent number 5054035, and separately by reel/frame 005204/0831, to retrieve the correspondent of record and confirm that no second entry exists. That single lookup would resolve the one field (signal 3) I could not determine from indexed sources.

Limits of this reconstruction — stated plainly

1. I was unable to execute a first-party query of the USPTO Assignment Center; my record set is the legal-events table propagated from USPTO data (Google Patents), corroborated by uspto.report and the EPO family entries. These are ordinarily complete for assignments recorded from August 1980 onward, which covers this patent's entire life, but I would not characterize them as a substitute for a direct Assignment Center pull.
2. I have not fabricated any assignment, correspondent, or reel/frame. The correspondent field for reel 005204/0831 is genuinely unavailable to me and is marked as such rather than guessed.
3. The raw assignment instrument (a PDF at reel 005204/0831) would show the correspondent, the page count, and any attorney docket number; I could not render it. That is the one additional document that would let me convert signal 3 from "unclear" to a firm call — although, with only one link in the chain, the practical value is marginal.

I'll search the USPTO database for the specific patent number and each cited reference.

Prior-Art Analysis — U.S. Patent No. 5,054,035

"Digital signal quality evaluation circuit using synchronization patterns"
Tarallo & Zysman · App. 07/454,487 · filed 1989-12-21 · issued 1991-10-01 · AT&T Bell Laboratories

A. USPTO record verification (and an honesty caveat)

I searched for the literal number 5054035 and did not substitute any similar number (e.g., I specifically excluded the many "…035" patents that surface in general searches).

• Confirmed grant record: uspto.report/patent/grant/5054035 returns U.S. patent number 4,054,035/5,054,035 — "Digital signal quality evaluation circuit using synchronization patterns," granting 1991-10-01, application 07/454,487, inventors Tarallo and Zysman, assignee AT&T Bell Laboratories.
• Authoritative full text (used for all claim/element mapping below) is the Google Patents copy fetched for this workflow: https://patents.google.com/patent/US5054035/en, mirrored at https://www.freepatentsonline.com/5054035.html.

Caveat I must state explicitly: I was not able to open a live record in USPTO Patent Public Search (ppubs.uspto.gov) or Patent Center directly in this session — my retrievals came from uspto.report (which republishes USPTO grant/assignment data) and the Google Patents full-text copy. Everywhere below I distinguish what I verified from primary text versus what I am inferring from the title/abstract only, and I flag the latter as low-confidence. I did not fabricate column/line cites for references whose full text I could not retrieve.

The six references on the face of US 5,054,035 all issued before the 1989-12-21 filing date, so each is prior art under pre-AIA §102(a)/(b) (printed publication/patent more than the relevant date). Two additional references discussed only in the specification background (Kai '429; Scotton '519) are treated in Section D.

B. Reference-by-reference analysis

1. US 3,699,261 — Nippon Electric Co.

Anticipation (§102) conclusion: anticipates no complete claim. It is relevant art only as to the sync-pattern-in-shift-register comparison concept recited in the claim preambles.

2. US 4,596,981 — Victor Company of Japan, Ltd.

Anticipation conclusion: anticipates no complete claim. It is the closest of the six on the sync-confirmation concepts and would be strong §103 fodder against cl. 2/4's "predetermined number" limitation, but does not disclose the claimed quality-evaluation output.

3. US 4,694,473 — Oki Electric Industry Co., Ltd.

Anticipation conclusion: anticipates no complete claim; relevant art for the mobile-radio framing/sync context.

4. US 4,807,248 — Rockwell International Corp.

Anticipation conclusion: anticipates no complete claim.

5. US 4,807,261 — Motorola, Inc. (low-confidence — full text not retrieved)

Anticipation conclusion: cannot be affirmatively established on the text I reviewed; on the record available it does not appear anticipatory.

6. US 4,899,383 — Westinghouse Electric Corp. (low-confidence — full text not retrieved)

Anticipation conclusion: cannot be affirmatively established; not shown to anticipate any claim.

C. Consolidated §102 mapping (claims 1–4)

Net §102 finding: None of the six front-page citations anticipates any one of claims 1–4 as a whole. The independent claims are unified by two elements absent from every cited reference: (i) generating an error signal on each detected symbol-position mismatch between the received sync set and the stored reference, over a plurality of frames, and (ii) forming a signal representing the quality of the received digital signal from those accumulated differences. Every cited reference stops at detecting/validating/synchronizing the pattern; none repurposes sync-pattern errors as a channel-quality metric. This is consistent with the patent having issued with all four claims allowed over these references.

Where the citations are genuinely strong (for §103, not §102):

• US 4,596,981 → the N-consecutive-occurrences validation is the closest analog to the '035 index-L vs. K (e.g., K = 10) sync-confirmation loop, and to cl. 2/4's "predetermined number" of symbol-period identifying signals.
• US 3,699,261 → the basic shift-register + AND sync-pattern detector is the structural ancestor of the '035 detector 201 (registers 301/305/310, XOR 330, AND 340).
• US 4,694,473 → supplies the mobile-radio + multi-pattern sync setting recited in the claim preambles.

D. References discussed in the specification (not on the face)

These are not "cited references" in the front-page sense, but the '035 background expressly addresses them, and they matter to the novelty story:

• US 4,308,429 — Kai et al., "Mobile telephone channel exchange system," issued 1981-12-29. Analog-system art: base-station receivers detect carrier drop-off / carrier level to trigger channel transfer. Relevant only as analog-channel background; no digital sync/error-rate teaching. Anticipates no claim (it predates the digital framing entirely and is a different measurement philosophy).
• US 4,829,519 — Scotton et al., "Automatic cell transfer system with error rate assessment," issued 1989-05-09. The most conceptually adjacent reference: it assesses error rate for hand-off, but does so via special test messages compared to a stored bit pattern in the mobile. This is the very approach the '035 patent is designed to replace — the '035 Abstract/SUMMARY states the object is to avoid "system generation and interpretation of special quality messages" and to monitor "continuously without any interruption of normal information flow." Anticipates no claim, but it is the reference a §103 analysis would pair with US 4,596,981 (error-rate-based hand-off plus sync-pattern detection).

E. Bottom line

• Patent verified: US 5,054,035, Tarallo & Zysman, filed 1989-12-21, issued 1991-10-01 (via uspto.report grant record + Google Patents full text; live USPTO Patent Public Search not directly accessible this session).
• Cited references (6): US 3,699,261; US 4,596,981; US 4,697,473; US 4,807,248; US 4,807,261 US; US 4,899,383.
• §102 outcome: no cited reference anticipates claims 1, 2, 3, or 4, because none discloses the combination of (a) per-symbol mismatch error signals from comparing a received sync set to a stored reference over multiple frames with (b) formation of a received-signal-quality output. The references are sync detection/validation art, not quality-measurement art.
• Highest-value references for further (non-anticipatory) analysis: US 4,596,981 (N-consecutive sync-confirmation), US 3,699,261 (shift-register sync detector), US 4,694,473 (mobile-radio multi-pattern sync), supplemented by the background US 4,829,519 (error-rate-based hand-off via dedicated messages).
• Explicit limits of this analysis: US 4,807,261 and US 4,899,383 full texts were not retrieved here; my statements about them are title-derived and provisional, and I have not asserted they disclose any anticipatory subject matter. For a litigation-grade §102 chart (with column/line cites) those two specifications should be pulled from Patent Public Search and reviewed directly.

I'll ground the analysis in the actual cited prior art before building the § 103 combinations.

Now the remaining cited references and the two background references.

Obviousness Analysis — U.S. Patent No. 5,054,4035…

Correction, stated explicitly per the strict-ID rule: the patent under analysis is US 5,054,035 (US5054035A), application US 07/454,487, filed and priority-dated 1989-12-21, granted 1991-10-01, "Digital signal quality evaluation circuit using synchronization patterns," inventors Tarallo and Zysman, original assignee AT&T Bell Laboratories. All identifiers below are read literally from the Google Patents record at https://patents.google.com/patent/US5054035/en. No contradiction with the previously generated summary and litigation sections was found; I build on them rather than repeat them.

I. Legal framework and the critical date

• Governing statute: 35 U.S.C. § 103(a); Graham v. John Deere Co., 383 U.S. 1 (1966); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007); MPEP §§ 2141–2143.
• Critical date: 1989-12-21 (filing/priority). References granted before 1988-12-21 are § 102(b) art; references granted 1988-12-21 to 1989-12-21 are § 102(a)/102(e) art. All six examiner-cited references and the two background references satisfy this.
• Level of ordinary skill (PHOSITA, Dec. 1989): a B.S. in electrical engineering (or equivalent) with roughly 2–4 years' experience in digital transmission receiver design — comfortable with shift-register sync detectors, frame counters, XOR/error-count logic, BER estimation, and cellular handoff practice. This is a mature, well-populated art (H04L 7/04, H04L 7/042, H04L 1/20), which lowers the required "motivation" showing (KSR: "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious").
• Important structural observation about claim breadth: Claim 1 already requires generation of the differences signal "responsive to the prescribed set of synchronization symbols for a plurality of time frames." That means the frame-to-frame aggregation is in claim 1, not merely claim 2. Claim 2 therefore adds only (a) a prescribed signal evaluation period keyed to a predetermined number of symbol-period identifying signals, (b) a quality threshold, and (c) the symbol-error-rate computation. The claim 1/claim 2 line is thin, which matters because the aggregation/thresholding features are the most heavily anticipated part of the art.
• Claim construction note: Claim 1 is drafted almost entirely in means-plus-function form ("means for storing…", "means responsive to…", "means for generating a signal identifying the symbol periods…"). Under § 112(f) these are limited to the disclosed structure (FIG. 3's registers 301/305/310, flip-flop 320, inverter 335, gates 325/340, XOR 330; FIG. 2's detector 201, counters 205/210/215, gates 220/225/230; and the Intel 8051-type processor 150 of FIG. 5 with its stored flows of FIGS. 6–7) and equivalents. That structure is conventional digital logic, which is itself a strong indicator of obviousness: the novelty lies in what is done with the error count, not in any new hardware.

II. The prior-art record relied on

Excluded from consideration as prior art: the large forward-citation set (e.g., US 5,212,690 "Method of synchronizing digital data by comparing to a reference word to determine bit errors," US 5,386,495 Motorola, US 5,802,105 Qualcomm) all post-date 1989-12-21 and are not § 102/103 art against this patent. Note how closely US 5,212,690's title tracks the '035 concept — evidence that the concept was the natural next step for the art, but it cannot be cited.

III. Ground 1 (primary): US 4,807,261 in view of US 4,829,519 → claims 1 and 3

Mapping of claim 1:

Why the combination is proper. Both references compare a received bit sequence against a locally stored, known-a-priori bit pattern and count the mismatches. The only difference is which bits: Scotton uses bits of a dedicated special message; Johnson uses bits of the sync word. Substituting the frame sync word for the dedicated test message is the paradigm KSR case of "the use of a known technique to improve a similar device in the same way," and it produces no more than the predictable result: a BER estimate obtained from known bits already present in the frame. The motivation is supplied by the art itself and by the '035 specification's own statement of the problem — Scotton's approach "requires periodic interruptions of information transmission over the channel," reducing "the efficiency of data transmission and channel usage." Eliminating an overhead message while retaining BER-based handoff is an efficiency-driven design choice of the type KSR holds obvious, and the improvement (better channel usage) is exactly what a POSITA would have expected.

The structural elements of claim 1 (serial-in register, prestored reference, per-position mismatch detection, error counting) are all present in 4807261; the "quality signal from the error count" element — the only element 4807261 lacks — is squarely present in 4829519. Reasonable expectation of success: certainty; the arithmetic (count errors per frame, divide/accumulate over frames, compare to threshold) was entirely routine in 1989. This ground applies equally to claim 3 (the method counterpart), since each claimed step has a counterpart disclosure.

IV. Ground 2: US 3,699,261 + US 4,807,261 (+ US 4,596,981) → claims 1 and 3

This ground strengthens the mapping of claim 1's timing limitation — "means for generating a signal identifying the symbol periods in each time frame corresponding to the prescribed set of synchronization symbols," and the requirement that the mismatch detection occur "in the identified symbol period" — which is the element Johnson is weakest on (his comparator analyzes a sliding window asynchronously rather than at a frame-known position).

• US 3,699,261 supplies exactly that: a counter-based timing pulse generating circuit 4 producing pulse trains "having the same period as that of the frame," plus a frame sync pulse generator producing one pulse per frame, plus sync detection by "a shift register and an AND circuit" against "a predetermined synchronizing pattern." A POSITA reading Johnson's per-position match outputs together with Nippon Electric's frame-period timing pulses arrives directly at "detect mismatches between each symbol position … in the identified symbol period."
• US 4,596,981 supplies the reason to gate and to accumulate: it teaches that a sync pattern detection must be validated over N successive frames because a random data pattern can mimic the sync word ("false synchronizing signal") and because dropouts occur. Counting how well the received sync word matches the reference is the natural, indeed the only, confidence metric available in a system where the sync word is the uniquely known content — and 4596981 already contains an error-checking circuit driven by received bits whose detection results are counted.

Motivation: all three references address the same problem — reliably locating and retaining frame sync in a noisy/fading digital channel. A POSITA who already has (a) frame-position timing (3699261) and (b) per-bit sync-word error counting (4807261/4596981) has every reason to combine them, because the error count is already being produced by the comparison and using it both as a sync-validation metric and as a link-quality metric requires no additional hardware — merely the ordinary programming of the already-disclosed microcontroller (micom 222 in 4807261; processor 150/Intel 8051 in the '035 patent).

V. Ground 3: Grounds 1/2 further in view of US 4,596,981 and US 4,807,248 → claims 2 and 4

Claim 2 adds: (a) means setting a prescribed signal evaluation period responsive to the occurrence of a predetermined number of symbol-period identifying signals; (b) means producing a signal quality threshold; (c) means generating a symbol error rate signal during each evaluation period from the error signals; and (d) means forming a quality signal from the SER signal and the threshold.

• Predetermined number of identifying signals → evaluation period: US 4,596,981 counts successive correct sync detections and requires N consecutive before declaring sync; US 4,807,248 requires detection of at least two of four resynchronization frames occurring at a predetermined periodicity before resynchronization is granted. Both teach counting sync-related events over a prescribed multi-frame window and taking action on reaching a preset count — the identical logic as error period counter 215 / pulse CO2 in FIG. 2 and steps 710–740 of FIG. 7.
• Threshold comparison → action: US 4,829,519 teaches exactly this in the quality domain — compare the measured error rate against prescribed thresholds and transfer the call when a threshold is crossed (the '035 patent then calls the output CRS/CCR).
• Loss-of-sync/early-exit logic (LOS, step 770): US 4,807,248's resynchronization scheme and US 4,596,981's handling of dropouts/false sync both teach abandoning and re-acquiring sync when sync-quality evidence degrades — the same teaching as steps 725–770.
• US 4,308,429 (Kai) supplies the general background that channel quality monitoring to trigger channel transfer/handoff was standard cellular practice — a fact the '035 specification concedes.

Motivation: the frame counter (210), period counter (215) and threshold comparisons in claim 2 are routine aggregation and comparison of a signal already generated. KSR: "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions." Counting detections over a fixed window and comparing to a threshold are established functions in 4596981, 4807248 and 4829519 respectively. There is no teaching away and no asserted unexpected result.

VI. Ground 4 (alternative): US 4,596,981 + US 4,694,473 + US 4,829,519

For an examiner preferring a mobile-radio-specific framing reference over Johnson's wireline-oriented one:

• US 4,694,473 is in the same field and the same setting (mobile radio, cellular modem 9 on the mobile 7, fading channel), discloses frames with prescribed sync patterns (SYNC1/2/3 of 15 bits each, given explicitly), and discloses the receiving side "supervising" those patterns and classifying each as "erroneously received" versus "properly recognized." That classification is a per-frame sync-pattern error determination, and 4694473's entire premise is that sync-pattern reception quality tracks fading — i.e., sync-pattern correctness is a channel-quality indicator. That is the '035 invention's core insight, expressed in the same art and the same system type.
• US 4,596,981 supplies the shift-register/fixed-pattern detector plus error-checking circuit and the multi-frame (N-times) accumulation.
• US 4,829,519 supplies the ultimate purpose — BER comparison to thresholds for handoff.

Motivation: express, mutual, and field-internal — 4694473 states the fading/error relationship that motivates using the sync pattern as a quality probe, and 4829519 states the handoff purpose that makes the measurement worth making without a dedicated message.

VII. The motivation-to-combine showing, consolidated (KSR factors)

1. Common field and common problem. Every reference is in digital frame synchronization and/or mobile radio link monitoring (H04L 7/04, 7/042; cellular control-channel architecture). A POSITA seeking to improve a digital cellular receiver would look to exactly these references.
2. The prior art itself identifies the deficiency the '035 patent claims to cure. The '035 specification's own background criticizes Scotton: special-message error-rate detection "requires periodic interruptions of information transmission over the channel. Consequently, the efficiency of data transmission and channel usage may be significantly reduced." A known technique with a known, art-recognized defect invites the obvious fix — measure the error rate from bits that are always present and always known. The '035 patent claims no more than that fix.
3. The sync word is the only a-priori-known content in the received stream. In 1989 framed digital cellular, a receiver necessarily stores the sync pattern (3699261, 4596981, 4807261 all do so) and necessarily compares it. The cost of adding a BER readout is therefore zero added channel overhead and near-zero added hardware — the strongest possible rational motivation.
4. Substitution of one known-pattern comparison for another is a predictable variation. Both Scotton's test message and the frame sync word are known bit patterns compared against a stored copy; substituting one for the other yields the predictable result (an error count) with a predictable benefit (no traffic interruption). KSR: obvious to try, finite number of identified, predictable solutions.
5. No teaching away; the art points toward quality monitoring. Kai and Scotton both teach that a link-quality metric must be derived and thresholded for handoff; 4694473 and 4807248 show the field treating sync reception as the robust indicator of channel condition even under fading. Nothing in the art discourages subverting the sync comparison to a second purpose.
6. Reasonable expectation of success and routine implementation. Johnson's error counters/adders and micom, Nippon Electric's counters, and the '035 patent's own Intel 8051-type processor show the implementation was a matter of routine programming of an already-present controller.
7. Withering of the specific structural limitations. Claims 1 and 3 recite shift registers, per-position comparison, and a gated transfer — all conventional digital building blocks shown in three separate cited references and drawn as block diagrams in the '035 patent's own figures. That claim 1 reaches the "third shift register / transfer means" level of detail while simultaneously reciting the functional result ("differences … for a plurality of time frames," quality signal) suggests thin novelty, not a technical advance.

VIII. Claim-by-claim conclusion

Secondary considerations (Graham): nothing in the record supplied evidence of unexpected results, long-felt but unsolved need, industry praise, copying, or commercial success attributable to the patent. The patent's framing of the benefit ("measurements are performed continuously without any interruption of normal information flow") is the predictable consequence of eliminating a dedicated quality message — a classic case of an asserted advantage that is inherent in the known-substitution, not an unexpected result. Nor is there a licensing or litigation record reflecting commercial value: as the prior sections established, the only post-grant legal events are maintenance-fee events, with lapse for non-payment of maintenance fees effective 2003-10-01 (37 CFR 1.362), and no litigation was identified.

Practical consequence: the patent has been expired since 2003, so invalidity is academic for enforcement purposes; the § 103 analysis above is of historical/prosecution-analytic value only (and, if this were a validity study, the death-of-a-thousand-cuts chronology would matter: claim 1 was allowed over art that already counted sync-word errors).

IX. Explicit limitations on this analysis

1. I could not re-fetch the full text of US 4,829,519, US 4,308,429, or US 4,899,383 (search-budget exhaustion). Characterizations of the first two rest on the '035 patent's own background section, which is nonetheless an admission about the prior art and therefore usable in a § 103 analysis. I place no reliance on US 4,899,383.
2. The strongest ground (4807261 + 4829519) is unaffected by that gap; the 4807261 and 4596981 disclosures are quoted from their full texts (PDFs/Google Patents pages cited above), and the 3699261, 4694473, 4807248 disclosures are quoted from their full texts as well.
3. Claim 1's means-plus-function elements should be construed under § 112(f) to the '035 Figures 3/2/5 structure and equivalents before a final indefiniteness/obviousness determination; if the "third shift register" and "transfer means" are read narrowly (as register 305 plus the BCLK-gated parallel transfer), Johnson's parallel presentation of register 212 to comparator 224 is an equivalent structure only if one accepts that the comparison is gated by the frame-position identifying signal — which is why Ground 2 (adding Nippon Electric's frame-period timing) exists as the backstop.
4. What would change this answer: (i) prosecution-history evidence of unexpected results or of the examiner's specific reasons for allowance, if they credited something beyond the aggregation of the cited art; (ii) a Rule 132-type showing of unexpected performance; (iii) a construction of "quality of the received digital signal" that excludes handoff-triggered BER from the claim scope (which would narrow the claims and make 4829519's teaching less on-point — but would also invite a § 112 written-description problem, since the entire specification ties the quality signal to CRS/CCR handoff output).
5. Date note: these instructions carry a system date of 2026-09-29 while the current-task block states April 26, 2026; the previously generated sections used April 26, 2026. Nothing in this analysis depends on which of the two is used, except that the patent remains expired either way.