US 5282204

US 5,282,204 — Search & Summary

Search scope and result: I searched for the exact number 5282204 / 5,282,204. The number resolves to a single, unambiguous grant. I found no CAFC docket (2026 or otherwise) or Federal Circuit proceeding naming this patent, and no indication of any 2026 appellate activity. That is consistent with its status: the patent expired for failure to pay maintenance fees, with an anticipated expiration of 2012‑04‑13 (per the Google Patents legal‑status record). A 2026 CAFC appeal over a 1994 patent that lapsed in 2012 would be highly unusual, and nothing in my search supports one. Uncertainty note: I cannot fully rule out a reissue, reexamination, or a passing citation in an appellate brief that a general web search would not surface; treat the "no CAFC activity" finding as a negative search result, not a certified docket clearance.

Bibliographic data

Sources: Google Patents https://patents.google.com/patent/US5282204/en ; FreePatentsOnline https://FreePatentsOnline.com/5282204.html ; uspto.report https://uspto.report/patent/grant/5282204

Abstract (as issued)

A data communications system is overlaid on a voice‑based trunked radio system. Digital data packets are transmitted over available radio channels, enabling data communication between a host dispatch system and mobiles via a base station. Radio channels associated with trunked channel groups are accessed when available by a communications controller, which communicates with mobiles over multiple radio communication links and monitors channels to detect when they are unused for voice and therefore available for data overlay. When the system detects that analog voice transmission has ceased on a particular channel, the trunked channel group association of that channel is switched from a "voice" group to a "data" group, and data packets are then transferred over it.

Plain‑language overview of the independent claims

There are ten independent claims — five apparatus claims (1, 2, 5, 7, 11) and five method claims (12, 13, 16, 18, 22). All share the same core: a communications controller monitors trunked channels, detects a channel free of analog voice, re‑assigns that channel's trunked‑group membership from a voice group to a data group, and then transfers data packets over it. Each independent claim adds a distinct feature.

Apparatus claims

• Claim 1 — Core apparatus. "Accessing means" (a communications controller at the base, configurable for multiple radio links) watches trunked channels, and when voice stops on a channel it switches that channel's group association from voice to data; "transferring means" (coupled to the host dispatch system) then moves data packets over the channel. Added limitation: the accessing means mutes audible reception of data‑packet transmissions at the mobile units when it detects such a transmission.
• Claim 2 — Core apparatus plus the transmission format: packets are sent bit‑serially, each preceded by a synchronization pattern comprising a repeated pseudo‑random code detectable by auto‑correlation at the receiving mobile or base.
• Claim 5 — Core apparatus plus reliability: after each packet, the transferring means sends a request for data acknowledgment, itself preceded by the sync pattern, and resends it up to a specified number of attempts while the packet remains unacknowledged.
• Claim 7 — Core apparatus plus protocol architecture: the digital data are assembled as a Remote Procedure Call (RPC) communicated per the OSI stack hierarchy at the Logical Link Control (LLC) and Medium Access Control (MAC) sublayers.
• Claim 11 — Core apparatus plus diagnosing means remotely coupled to the accessing means, monitoring access wait times for voice and data traffic, accumulating statistics as a function of data‑packet transmission duration, and simulating the system to predict data‑overlay performance so operating parameters can be adjusted.

Method claims

• Claim 12 — Core method (providing the communications controller, monitoring channels, switching the voice→data group association) with the added step of muting audible reception of data packets at the mobiles.
• Claim 13 — Core method plus bit‑serial packet transfer, each packet preceded bit‑serially by a synchronization pattern of repeated pseudo‑random code detectable by auto‑correlation.
• Claim 16 — Core method plus the acknowledgment request step (sync‑pattern‑preceded, resent up to a specified number of attempts while unacknowledged).
• Claim 18 — Core method plus RPC over the OSI stack, at the LLC and MAC sublayers.
• Claim 22 — Core method plus monitoring access wait times, accumulating statistics as a function of data‑packet duration, and simulating to predict data‑overlay performance.

Notable dependent claims: claim 3/14 (the sync code's leading portion is a toggling binary pattern for phase‑timing recovery); claims 4 and 15 (the pseudo‑random code is, in hexadecimal notation, "AB376938BCA3081F", transmitted left to right with "A" first); claim 6/17 (after exhausting retries, resend at non‑linearly backed‑off intervals); claims 8/19 (application‑sublayer interface with a symmetric predefined command set); claims 9/10 and 20/21 (the command set includes send/receive‑message commands and status‑listing commands).

Detail worth flagging

• The specification describes the underlying trunking protocol as the E. F. Johnson "Logic Trunked Radio" (LTR) system, and the decision logic as residing in an 80188 processor in the modems; the base front end is an 80186‑based ARTIC card with an RS‑232 interface (per the patent text).
• The specification states the sync pattern's theoretical falsing rate is "5.4 exp(-20)/bit (i.e., once in 120 million years)" and that a 64‑bit correlator is used, with a 64‑bit (no‑error) threshold preferred.
• Prior art cited on the face includes WO 1988/008648 (Motorola, dynamic data‑channel allocation on trunked systems) and US 4,837,858 (Motorola, trunked voice/data subscriber unit) — the closest topical references. Non‑patent citations include Bustillo et al., "Datamovil…" (IEEE, May 1989) and Stern, "An Improved Integrated Voice/Data Mobile Radio System" (IEEE; the record prints the year as "May 1900," an apparent typo in the source).
• RaCoTek later obtained a related overlay patent, US 5,548,805, "Data communication system using spectral overlay" (cited in the "Cited By" list), which may be relevant for family/portfolio context.

Confidence: High on bibliographic data, abstract, and claim content — these come directly from the authoritative full text you supplied and corroborating patent databases. Low/uncertain on CAFC 2026 activity — I found none, and given the 2012 lapse I have no basis to assert any exists. If you need certified docket-level assurance, that would require a direct query of the CAFC CM/ECF docket and the USPTO Patent Trial and Appeal Board/Patent Center records rather than open‑web search.

I'll search for litigation involving US patent 5282204 across patent litigation databases and court sources.

Initial results show the patent is prior art in other patents and appears in Racotek/Sipco documents, but no direct litigation yet. Let me search more targeted litigation sources.

Let me check Google Patents' litigation data and search for Racotek as a litigant.

Summary of Findings: Litigation Involving U.S. Patent No. 5,282,204

No litigation naming U.S. Patent No. 5,282,204 as an asserted or challenged patent was found in the sources searched. Based on my searches, there does not appear to be any known court case in which this patent has been asserted, adjudicated, or subjected to a validity challenge.

What I searched and what the results show

I searched patent-litigation-oriented sources and general web indexes for the specific number and its assignee:

1. Google Patents (US5282204A) — The patent's prosecution/family record lists its citation as prior art in other patents (e.g., WO1995026613A3 and WO2001067675A3 both cite "US 5282204 A" under "Documents Considered to be Relevant"), and it appears in "Cited By" and "Families Citing" patent lists. None of these entries is a litigation event — they are patent-to-patent citations only. The record shows a single application (US07/869,011), one patent, and status "Expired – Fee Related" (anticipated expiration 2012‑04‑13). No litigation tab or case data is present.

2. USPTO/PTAB petition documents — US5282204 ("Apparatus and Method for Overlaying Data on Trunked Radio," assignee RaCoTek, Inc., 1994) shows up only as a cited prior-art reference in unrelated prosecution documents (e.g., in a Sipco-related prior-art listing and in an IPR prosecution history). Again, this is prior-art citation, not litigation.

3. CourtListener / RECAP and CAFC-adjacent materials — Searches returned unrelated patent cases (e.g., Quadlux v. Amana, Motorola v. Hytera, Verosol, etc.). None involved US5282204.

4. Assignee search (RaCoTek / Racotek, Inc.) — The only litigation-adjacent hits are: (a) a Racotek–Ericsson GE marketing/supply agreement from 1991 (a business relationship, not a lawsuit); and (b) Racotek's later US 5,548,805 ("Data communication system using spectral overlay," 1996), which is a different patent and is itself cited as prior art. I found no Racotek-initiated infringement suit asserting the '204 patent.

Important caveats

• I was unable to complete a full query of the Unified Patents litigation portal and could not directly access PACER (subscription/authentication required). These are the two sources most likely to surface a suit, if one exists.
• Docket Navigator, Lex Machina, and Westlaw/IPRLit are paywalled and were not searched.
• The patent expired in 2012, and its statutory term ran from a 1992 filing; if it was ever asserted, it most likely would have been in the 1990s–2000s. My searches did not surface such a case.
• I did not locate any case number, jurisdiction, or party identification for this patent in any source.

Bottom line

Based on the available search results, I cannot identify any known litigation involving U.S. Patent No. 5,282,204. Every appearance of "5,282,204" I found relates to prior-art citation or patent-family/assignment records, not to a lawsuit.

If you need a definitive negative, I recommend running the exact number through Unified Patents' litigation case list, Docket Navigator, Lex Machina, and PACER directly — those were beyond the reach of my available tools, and I do not want to represent my search as exhaustive.

I'll verify the structured-block default against live sources before writing anything up.

No PTAB hits so far. Let me run a couple more targeted checks (assignee-based and litigation-based) before concluding.

One last check on assignee/aggregator angles before I finalize.

PTAB Proceedings on US 5,282,204 — Trial-History Analysis

Critical framing note: the answer requested here ("surface every AIA trial proceeding") is a negative. The canonical structured source — the "PTAB proceedings on file" block derived from the USPTO Open Data Portal — returns no AIA trial proceedings for US 5,282,204, and my independent web searches surface none. I did not find any IPR, PGR, or CBM number naming this patent, and I will not invent one. Below I state what exists (nothing), what the empty record means, and what a defendant actually needs to know — which, for this patent, is a fact far more dispositive than any IPR.

Proceedings overview

Total AIA trial proceedings on US 5,282,204: zero (0). Breakdown by status: 0 active, 0 claims invalidated, 0 claims sustained, 0 settled, 0 institution denied — there is no proceeding to break down. Bottom-line defensive posture: this is not a "hardened by surviving IPRs" situation, and it is emphatically not a "claims 1–5 are cancelled — check your demand letter" situation either. It is a no-proceedings situation layered on top of a patent that expired for failure to pay maintenance fees with an anticipated expiration of 2012-04-13 (Google Patents legal-status record: https://patents.google.com/patent/US5282204/en). The defensive value of the empty PTAB record is therefore essentially nil on its own, and the real defense is the expiration, not the trial history.

Confidence: High that no AIA proceeding exists as of the most recent ODP ingest and as of my searches today (2026-09-27). This is a negative search result, not a certified docket clearance. PTAB E2E and Patent Center are the authoritative registries; if you need docket-level certainty, query PTAB E2E directly for the patent number and for "Racotek"/"RaCoTek" as party name.

What the record does show — citations, not proceedings

Because there are no proceedings to write up in the per-proceeding format requested, I'm substituting the closest-analogue evidence: places where this patent appears inside someone else's PTAB or prosecution record as cited art or as a search hit. None of these is a proceeding against US 5,282,204.

• Not a proceeding — a party's prior-art search log. A document hosted on PTAB's own site (petition artifact, proceeding IPR2017-00860-era docket materials, https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1460450](/patent/1460450)/download-documents) contains a third party's invalidity search string reading ("5282204" | "5592491" | "5757783" | "5790938").PN. OR ("6044062").URPN. — i.e., US 5,282,204 was swept into a search list alongside Eon's US 5,592,491 and Communique/StatSignal's US 6,044,062. This is the requesting party's search query, not a petition challenging '204. Do not cite it as a proceeding.
• Foreign prosecution citation. WO 1995/026613 (Nokia) lists US 5,282,204 A (Shpancer et al.), 25 Jan 1994, abstract as category "A" art against claims 1–21 of a different application. Category "A" = document defining general state of the art, not considered particularly relevant. This is the clearest signal that '204 has prior-art value but was never itself the target of an AIA trial.
• Self-citation in the assignee's own later patent. RaCoTek's US 5,548,805 ("Data communication system using spectral overlay") cites US 5,282,204 in its Background as the "time domain data overlay" that the '805 spectral-overlay invention improves upon — characterizing '204's data rate as ~4800 baud and criticizing its latency/back-off coupling. Useful to a defendant: the patent owner's own later patent describes '204's approach as deficient, which is a candid admission about the scope and limits of the '204 disclosure. (https://patentimages.storage.googleapis.com/9e/1e/6c/74bf8b2ef6ef78/US5548805.pdf)
• Family outcome for context. The non-US siblings all fell away: EP 0566957 A1 withdrawn, CA 2089777 A1 abandoned, KR 930022744 A abandoned, AU 665629 B2 ceased, BR 9300948 A discontinued. Only JP H06120887 A shows "pending" in the record. A family that was abandoned or withdrawn across every major non-US jurisdiction, followed by US lapse in 2012, is consistent with a portfolio that was never commercially enforced to the point of provoking IPRs.

Strategic summary

Claims status — CANCELED vs. SUSTAINED vs. UNTESTED. There is no IPR-derived claim status to report, because no claim of US 5,282,204 has ever been evaluated by the Board. Every one of the ten independent claims (apparatus claims 1, 2, 5, 7, 11; method claims 12, 13, 16, 18, 22) and all twelve dependent claims (3, 4, 6, 8, 9, 10, 14, 15, 17, 19, 20, 21) is UNTESTED at the PTAB. Everyone is technically "in force" in the sense of never having been adjudicated unpatentable — but that is a hollow status, because the patent's maintenance-fee lapse means the claims cannot be enforced for past or future infringement in the ordinary way. There is no narrowed, IPR-surviving claim set to point at; there is only the original 22-claim set and an expired term.

Estoppel landscape — § 315(e)(2). Inapplicable in the normal way, because no petitioner ever instituted an IPR, so no § 315(e)(2) estoppel attaches to anyone. Any prior-art ground (including the two closest references of record, WO 1988/008648 to Motorola on dynamic data-channel allocation in trunked systems and US 4,837,858 to Motorola on a trunked voice/data subscriber unit, plus the non-patent citations Bustillo et al., "Datamovil…" and Stern, "An Improved Integrated Voice/Data Mobile Radio System") remains entirely un-adjudicated and un-estopped. If a defendant were somehow facing assertion, invalidity tools are wide open: an IPR is legally available even against an expired patent, and ex parte reexamination under 35 U.S.C. §§ 301–307 remains available to any member of the public using patents-and-printed-publications art — no petitioner estoppel, no litigation standing requirement. But see the expiration point immediately below, which usually makes all of this unnecessary.

Pattern signals. No pattern exists. No petitioner has filed even one IPR on this patent, so there is no serial-petitioner signal. The patent owner has never pursued a PTAB appeal on this patent, because there was never a Board decision to appeal. No defensive aggregator (Unified Patents or comparable) appears anywhere in the chain — the only proceedings-adjacent hit is the incidental search-string mention above, and Unified Patents does not appear in the record for '204. Note the practical reason IPRs are rare on this patent: CBM review was never plausibly available — AIA § 18 limited CBM to claims covering a financial product or service, and a trunked-radio data-overlay patent does not meet that subject-matter test — and by the time the IPR regime matured (2012 onward), the patent was lapsing. The absence of IPRs here is not evidence the patent is strong; it is evidence the patent was not worth challenging.

One contradiction to flag with the earlier section. The previously generated "Patent summary" states it found no CAFC docket (2026 or otherwise) naming this patent and flags low confidence on that point. My searches today (2026-09-27) reach the same negative result, and it is mutually reinforcing rather than contradictory: a 1994 patent with an anticipated expiration of 2012-04-13 cannot generate a live 2026 Federal Circuit appeal over infringement, and with no PTAB FWD there was no Board decision capable of being appealed under 35 U.S.C. § 319/§ 141. The two sections agree; treat the combined finding as "no PTAB proceeding, therefore no PTAB-derived appeal."

Recommended next steps

• If no PTAB activity exists, say so plainly — it does here. The absence is itself the signal, and in this case it is amplified by the expiration. With zero proceedings and an anticipated expiration of 2012-04-13, there is no trial-stage milestone to track: no institution-decision deadline, no oral hearing date, no statutory one-year FWD deadline. There is nothing pending.
• For a defendant receiving any assertion letter citing US 5,282,204: the dispositive response is not an IPR argument — it is the maintenance-fee lapse and 2012 expiration, which is a complete answer that costs nothing to establish. Pull the Patent Center maintenance-fee record and the Google Patents legal-status entry (https://patents.google.com/patent/US5282204/en, "Expired - Fee Related," anticipated expiration 2012-04-13). A demand built on this patent in 2026 is, on its face, not worth a licensing payment.
• If you need certified docket-level assurance (which I cannot give from open-web search): query USPTO PTAB E2E (https://ptab.uspto.gov) by patent number 5,282,204 and by party name "Racotek"/"RaCoTek," and check Patent Center and the Federal Circuit CM/ECF docket directly. CourtListener's docket search for "5282204" is a reasonable secondary check. I found no proceeding; I did not certify that none exists.
• Preserve the invalidity record anyway, cheaply. Even though enforcement is moot, the un-adjudicated near art — WO 1988/008648, US 4,837,858, US 4,058,672, US 5,022,024, and the Bustillo and Stern papers — plus RaCoTek's own US 5,548,805 admission that '204's time-domain overlay was deficient, form a complete invalidity package at zero cost. If '204 is ever asserted as prior art against your own products or applications (the more likely modern role for this reference, as the WO 1995/026613 citation suggests), that package is what you will actually need.

Source links

• Google Patents (bibliographic + legal status): https://patents.google.com/patent/US5282204/en
• FreePatentsOnline (full text and claims): https://FreePatentsOnline.com/5282204.html
• uspto.report (prosecution/assignment record): https://uspto.report/patent/grant/5282204
• PTAB petition artifact containing the "5282204" search string (a party's search log, not a proceeding on '204): https://ptacts.uspto.gov/ptacts/public-informations/petitions/1460450/download-documents
• USPTO PTAB E2E (authoritative proceeding registry): https://ptab.uspto.gov
• RaCoTek US 5,548,805 (background admission re '204): https://patentimages.storage.googleapis.com/9e/1e/6c/74bf8b2ef6ef78/US5548805.pdf

I'll research the assignment chain and ownership history for this patent.

Let me dig into RaCoTek's corporate history and the assignment records.

Now let me check the USPTO assignment database records and later transfers.

I've reached the limit of my search budget. Here is the analysis based on the records I was able to retrieve, with candid flagging of what I could not verify.

Inventors

Pattern notes:

• No unusual inventor-departure pattern is evidenced. All three inventors assigned to RaCoTek on 1992‑06‑03, roughly seven weeks after the 1992‑04‑13 filing — a routine pre‑issuance, prompt inventor→company assignment, not a divestiture.
• Shpancer demonstrably stayed. He reappears as first‑named inventor on RaCoTek's follow‑on US 5,548,805, "Data communication system using spectral overlay," filed 1994‑08‑23 and assigned to Racotek, Inc. (Minneapolis, MN). A two‑year continuation of inventorship is the opposite of a pre-fire‑sale exodus.
• Name-variant flag: "Isaac Shpancer" (US 5,282,204) vs. "Isaac Shpantzer," Edina, MN (US 5,548,805). Same residence, same assignee, adjacent technology — almost certainly the same person under two spellings. I have not confirmed this against USPTO inventor-name records.
• I found no data on post‑1992 employment for Silverman or Grindahl. Unclear.
• The inventors also published publicly on this technology: I. Shpancer et al., "Open Data‑On‑Voice Systems for SMR's," presented at NABER's 1990 Annual Meeting (cited in the file of a later Racotek‑family patent), indicating they were RaCoTek technical staff pre‑filing.

Original assignee

RaCoTek, Inc. — the issued patent names "RACOTEK Inc A CORP OF" / "RaCoTek Inc"; the recorded assignment of 1992‑06‑03 names the assignee as "RACOTEK, INC. A CORP. OF DE." Corporate HQ was Burnsville / Minneapolis, Minnesota; incorporation was in Delaware.

• Line of business: Wireless mobile data communications for fleets and field service. Product line included the MPS II mobile system components (data terminal, printer, adaptive network modem — 1990 brochures), RacoNet wireless data service (1992), the KeyWare wireless distributed computing environment (1995), and Racotek mobile data terminals. Publicly documented marketing/tie‑ups include a 1992 technology licensing agreement with E.F. Johnson relating to RacoNet over E.F. Johnson radio equipment, and a September 1991 strategic relationship with Ericsson GE Mobile Communications.
• Did they ship a product embodying the claims? Yes — high confidence. The specification describes concrete hardware: an 80188 decision processor in each modem, an 80186‑based ARTIC front‑end processor card with RS‑232 interfaces, base/mobile modems 290/390, and push‑to‑talk switch 392. Contemporaneous Racotek sales brochures and product catalogs (1990–1993) confirm commercial mobile data products, not a paper portfolio. The patented overlay was the company's core offering.
• Current status: dissolved / absorbed. Racotek went public — Form S‑1 filed with the SEC 1993‑10‑22, amended 1993‑11‑04 (Nasdaq ticker Raco, later ZMBA). It operated at a loss, cut staff from ~100 to ~40 and closed its R&D lab; its CEO publicly stated the company was close to failure. The wireless‑IPR NextNet Wireless was spun out of Racotek. The company was renamed Zamba Solutions Corp., went off Nasdaq to the OTC market in June 2002, and was ultimately sold to Technology Solutions Co. of Chicago for $6 million (closed Dec. 29 of that year per the CEO's account). No Racotek/Zamba entity appears in the current USPTO owner record.
• No bankruptcy proceeding was found for Racotek/Zamba. The CEO's account shows creditor negotiations and near‑death financing, but he explicitly declined the "go bankrupt" route. I found no Chapter 7/11 filing — so the Kodak/Nortel-style fire‑sale signal is not present on the evidence I have.

Assignment timeline

Important limitation, stated plainly: I could not retrieve reel/frame numbers or the correspondent of record for this patent. The USPTO Assignment Center record viewer at https://assignmentcenter.uspto.gov/ was not directly queryable with the tools available to me, and no indexed page surfacing this patent's reel/frame entries appeared in search results. I will not invent reel/frame numbers. What follows is limited to what the Google Patents legal‑events record and corroborating sources actually state.

1992‑06‑03 (recorded) — Reel/Frame not retrieved

• Conveyance: Assignment ("ASSIGNMENT OF ASSIGNORS INTEREST")
• Assignor: Merv L. Grindahl; Isaac Shpancer; Jon M. Silverman (jointly)
• Assignee: RACOTEK, INC. A CORP. OF DE (per the notice text); the granted patent's front page lists "RACOTEK Inc A CORP OF"
• Correspondent: Not retrieved. A candidate lead only: Minneapolis patent attorney Paul L. Sjoquist is the named attorney of record on a sibling RaCoTek design patent, US D320,387 (assignee "RaCoTek, Inc. (Burnsville, MN)"). Truncated attorney fields ("Reinhard J.", "Marsha D.") also appear in the US 5,548,805 bibliographic record. None of these is confirmed as the recording correspondent on this patent — treat as a lookup lead for the Assignment Center, not a finding.
• Context: Routine pre‑issuance founder/inventor assignment to the operating company. Not a fire‑sale, not securitization, not a transfer to an asserter.

No post‑issuance assignment is recorded in the Google Patents legal‑events timeline for US 5,282,204. In particular, there is no recorded change‑of‑name (RaCoTek → Zamba Solutions), no assignment to Technology Solutions Co., and no assignment to any holding, licensing, or assertion entity. The last legal event before expiration is the 1994‑01‑25 grant, followed by the 2012‑04‑13 anticipated expiration and current status "Expired – Fee Related."

Interpretation of that silence: the patent most likely remained titled in Racotek / Zamba / its acquirer and was simply allowed to lapse for non‑payment of maintenance fees in 2012 when the wireless‑overlay business no longer existed. It is also possible that a late‑life transfer was executed but never recorded (common when portfolios are wound down), and unrecorded transfers are invisible to both the Assignment Center and Google Patents. I cannot distinguish these without a direct Assignment Center query by patent number.

Supplementary non‑USPTO chain events (corporate, not recorded assignments — for context only):

• 1989 — Racotek founded (Minneapolis, MN)
• 1992‑04 — Technology licensing agreement with E.F. Johnson
• 1993‑10‑22 — Form S‑1 filed; company goes public
• 1994‑01‑25 — US 5,282,204 issues
• Late 1990s — Renamed Zamba Solutions Corp.; NextNet Wireless spun out
• 2002‑06 — Delisted from Nasdaq to OTC
• Dec. 29 — $6M sale of Zamba to Technology Solutions Co. (Chicago)
• 2012‑04‑13 — US 5,282,204 lapses for fee non‑payment

Timeline diagram

timeline
    title Ownership of US 5282204
    1989 : Racotek founded in Minnesota
    1992 : Inventors assign to Racotek Inc of Delaware
         : EF Johnson technology license
    1993 : Form S-1 filed Racotek goes public
    1994 : US 5282204 issues to Racotek
    1990s : Racotek renamed Zamba Solutions
          : NextNet Wireless spun out
    2002 : Zamba delisted from Nasdaq
         : Zamba sold to Technology Solutions Co
    2012 : Patent lapses for fee non-payment

NPE / troll-pattern signals

Cross-reference / contradiction check vs. previously generated sections: No contradictions found. The earlier summary's "Current assignee: RACOTEK Inc A CORP OF / RaCoTek Inc" matches the 1992‑06‑03 recording verbatim, and its note that US 5,548,805 is a related Racotek overlay patent is confirmed here (assignee "Racotek, Inc. (Minneapolis, MN)"). One minor data discrepancy worth logging: Google Patents lists the priority date as 1992‑04‑13, while the Unified Patents portal entry for the same patent shows 1992‑04‑12. The authoritative full text says 1992‑04‑13; treat the Unified entry as a one‑day indexing artifact.

Verdict

Insufficient data — the chain consists of only the original assignment. The single recorded conveyance is the 1992‑06‑03 inventor→RaCoTek, Inc. (Delaware) "Assignment of Assignors' Interest," executed seven weeks after the 1992‑04‑13 filing; there is no recorded post‑issuance assignment to any NPE, aggregator, or successor. The record is fully consistent with a genuine operating‑company patent that stayed with its owner's corporate successor and was abandoned when it lapsed for fee non‑payment on 2012‑04‑13 — the antithesis of an assertion vehicle. Accordingly this patent shows zero affirmative NPE signals, and I decline to call it "operating‑company assertion" or "defensive" because neither an asserting owner nor a defensive aggregator is evidenced in the recorded chain.

Caveat on completeness: I could not reach the USPTO Assignment Center to pull reel/frame, correspondent, or execution‑date detail, and I could not confirm whether an unrecorded late‑life transfer occurred. The verdict would only change if a reel/frame entry surfaced showing a transfer to a licensing entity. Verify directly at:

• https://assignmentcenter.uspto.gov/ (search by patent number 5282204)
• https://assignment.uspto.gov/patent/index.html
• https://patents.google.com/patent/US5282204/en (legal events)

Confidence: High on the existence and substance of the 1992‑06‑03 assignment, on RaCoTek's operating‑company status, and on the absence of any downstream NPE assignee in every index I could reach. Low/uncertain on reel/frame numbers, correspondent of record, and any unrecorded transfers — these are unfilled gaps, not negative findings.

I'll ground this against the authoritative citation record and verify the key prior-art references.

Let me verify the remaining cited references to ground the descriptions accurately.

Prior‑Art Analysis — US 5,282,204 (RaCoTek)

Step 1 — Patent identification (exact‑number match only)

The number 5282204 resolves to exactly one grant; no similar‑number substitution was made:

Sources: Google Patents https://patents.google.com/patent/US5282204/en ; FreePatentsOnline https://FreePatentsOnline.com/5282204.html

Note on the citation list: Google Patents prints this patent's citations twice — as "Citations (9)" and again as "Patent Citations (10)." The tenth entry is US 5,022,024 B1, which is the reexamination certificate of US 5,022,024 A (Interdigital), not a separate disclosure. I treat them as one reference below.

Step 2 — The § 102 benchmark these references must meet

US 5,282,204 has ten independent claims (apparatus 1, 2, 5, 7, 11; method 12, 13, 16, 18, 22). Every one of them contains the same core limitation, and it is the limitation that matters most for novelty:

detecting an available channel "upon the cessation of transmission of analog voice information," such detection causing the "trunked channel group association of said available radio channel [to be switched] from a voice group to a data group."

Under 35 U.S.C. § 102, a reference anticipates only if it discloses every element of the claim, arranged as claimed, in a single reference. A reference that discloses dynamic voice/data channel allocation by measured data traffic, or that lets a terminal request data mode, does not by itself disclose a switch triggered by voice cessation plus the group‑association re‑mapping. I have applied that standard below.

Step 3 — The cited patent references

3.1 — The three "closest" trunked voice/data references

① US 4,831,373 A (the US counterpart of WO 1988/008648 A1) — Motorola, Inc.

• Citation: WO 1988/008648 A1, "Method for dynamically allocating data channels on a trunked communication system." Published 1988‑11‑03; priority/filing 1987‑04‑30 (also issued as US 4,831,373).
• Description (grounded): A central controller monitors data activity over a time interval; if activity exceeds a maximum it reserves an additional channel for data, and if data traffic is low it reallocates a data channel back to voice. Reassigns subscribers to balance load across data channels. Confirmed by Google Patents https://patents.google.com/patent/WO1988008648A1/en and FreePatentsOnline https://FreePatentsOnline.com/[4831373](/patent/4831373).html.
• § 102 relevance: This is the single most relevant reference on the reallocation of a trunked channel between voice and data use — the concept closest to the '204 group‑association switch. Potentially anticipatory of the channel‑allocation element of independent claims 1, 2, 5, 7, 11, 12, 13, 16, 18, 22. However, its trigger is measured data traffic, not cessation of voice; it allocates via ISW/OSW control‑channel signalling rather than re‑mapping a trunked group association; and it discloses no multi‑link communications controller at the base, no audible‑muting (claim 1/12), no sync pattern (claim 2/13), no RPC/OSI LLC+MAC layering (claim 7/18), and no diagnostic simulator (claim 11/22). On the record available it therefore does not anticipate any independent claim in full.

② GB 2,217,149 A — Motorola Inc

• Citation: "Voice/data communication system," published 1989‑10‑18; filing 1988‑03‑31.
• Description (grounded): A shared data/voice trunked system with a network control processor. A terminal requests voice mode; the processor grants it, operates the base station in voice mode, inhibits all other terminals from sending data during the voice call, then returns the base station to data‑mode‑only. Data priority is maintained at a set, programmable level. Source: https://patents.google.com/patent/GB2217149A/en
• § 102 relevance: Directly discloses mode switching of a base station between data and voice on a shared channel — arguably the nearest thing to the "voice↔data switch," and potentially relevant to claims 1 and 12 (controller‑driven switching). But the polarity is essentially inverted: here the system is data‑primary and voice is granted on request, whereas claim 1/12 requires detecting cessation of analog voice and switching from a voice group to a data group. No "trunked channel group association" re‑mapping is shown, and none of the sync‑pattern / ack / RPC / diagnostic features appear. Not anticipating on the present record.

③ US 4,837,858 A — Motorola, Inc.

• Citation: "Subscriber unit for a trunked voice/data communication system," published 1989‑06‑06; filing 1987‑04‑30.
• Description (grounded): A trunked voice/data subscriber operating in a voice mode or one of three data modes; monitors the voice control channel or an assigned data channel; requests a data channel over the control channel when none is allocated; may operate without re‑requesting once a data channel exists. Sources: https://patents.google.com/patent/[US4837858A](/patent/US4837858A)/en ; https://patents.google.com/patent/EP0358659A1/en
• § 102 relevance: Bears on the mobile‑unit / subscriber side of the "accessing means" in claims 1, 2, 5, 7, 11 and the "mobiles" element of method claims 12, 13, 16, 18, 22. It shows a trunked subscriber that alternates between voice and data behaviour, but it is a subscriber/terminal patent — it does not disclose the base‑side controller that detects voice cessation and switches the channel's group association. Not anticipating.

3.2 — The data‑over‑voice‑radio reference (relevant to the sync/format claims)

④ WO 1989/011193 A1 — E.F. Johnson Company

• Citation: "High speed data interface for land mobile communication system," published 1989‑11‑16; filing 1988‑05‑11 (US counterpart US 5,212,714). Sources: https://patents.google.com/patent/WO1989011193A1/en ; https://www.freepatentsonline.com/[5212714](/patent/5212714).html
• Description (grounded): A microprocessor‑based modem/data interface that transmits high‑speed data over existing trunked land‑mobile voice transceivers without a dedicated data channel. It "continually monitors the unfiltered audio input," recovers bilevel Manchester‑encoded data, and upon recognition of a predetermined "dotting pattern" disables the transceiver for voice transmission and reception and presents recovered data to the terminal via RS‑232.
• § 102 relevance: Notably relevant, because the '204 specification itself states the system operates "compatibly per known protocol of conventional trunked radio systems, such as the Logic Trunked Radio (LTR) system available from E. F. Johnson." This reference is the closest cited art to claims 2 and 13 (bit‑serial data over a trunked voice channel with a repeated/dotting synchronization pattern detected at the receiver) and touches the audible‑muting/squelch idea in claims 1 and 12 (disabling voice reception on detecting data). It does not, however, disclose the voice‑cessation‑triggered voice→data group‑association switch, nor the auto‑correlation pseudo‑random code of claims 2/13, the acknowledged‑packet protocol of 5/16, the RPC/OSI features of 7/18, or the simulator of 11/22. Strong as a § 103 combination candidate; not anticipating the independent claims as a whole.

3.3 — Background / infrastructure references (generally non‑anticipatory)

⑤ US 4,058,672 A — "Packet‑switched data communications system," International Telephone and Telegraph Corp.; filed 1976‑11‑10, published 1977‑11‑15.

• Grounds the packet‑switching/acknowledgment concepts. Potentially relevant only to the generic packet‑handling aspects of claims 5 and 16 (data‑packet transfer and acknowledgment), and not to any trunked‑radio element. It is a wireline/data‑network disclosure and does not anticipate any claim that requires a trunked radio channel or group association.

⑥ US 4,613,990 A — "Radiotelephone transmission power control," AT&T Bell Laboratories; filed 1984‑06‑25, published 1986‑09‑23.

• Power‑control art. No § 102 relevance to any claim of the '204 patent; it addresses transmitter power, an element absent from every claim.

⑦ US 4,737,978 A — "Networked cellular radiotelephone systems," Motorola, Inc.; filed 1986‑10‑31, published 1988‑04‑12.

• Background on networked/multi‑site radio systems. Potentially marginal background for the "multiple radio communication links" and roaming notions in claims 1/12 and 11/22, but cellular rather than trunked, and no data‑overlay or group‑association switching. Not anticipating.

⑧ US 4,792,948 A — "Distributed switching architecture," Data General Corp.; filed 1985‑08‑08, published 1988‑12‑20.

• Data‑processing/distributed‑switching background; not radio‑trunking art. No anticipation of any claim.

⑨ US 5,022,024 A (and US 5,022,024 B1 reexam certificate, 1999‑06‑22) — "Subscriber RF telephone system for providing multiple speech and/or data signals simultaneously over either a single or a plurality of RF channels," International Mobile Machines Corp. (later Interdigital); filed 1985‑03‑20, published 1991‑06‑04.

• Discloses simultaneous speech and data over one or several RF channels. Potentially relevant as background to voice+data coexistence (claims 1, 12), but it is a cellular/RF telephone architecture with no trunked group‑association switching and none of the overlay‑specific features. Not anticipating.

Step 4 — The two non‑patent citations ("Non‑Patent Citations (4)")

• Bustillo, J., et al., "Datamovil: A Practical Implementation of Tradamo Mobile Data Transmission Protocol," May 1989 IEEE, pp. 31–37. A practical mobile‑data transmission protocol over radio — potentially relevant background to claims 1/12 (mobile data over a radio channel), and possibly to packet/retry aspects (claims 5/16), but it is a mobile‑data protocol paper, not a trunked voice→data group‑association scheme.
• Stern, H.P., "An Improved Integrated Voice/Data Mobile Radio System," Dept. of Electrical Engineering, University of Texas at Arlington, IEEE, pp. 311–316. Integrated voice/data mobile radio — conceptually close to the '204 problem statement (claims 1/12). Record caveat: the patent's own citation prints the year as "May 1900" — an apparent typographical error in the source. Per the operating rules I do not auto‑correct it; the correct date cannot be confirmed from the record as printed.

Step 5 — Bottom line on § 102

Most relevant prior art: in descending order — (1) WO 1988/008648 A1 / US 4,831,373 and (2) GB 2,217,149 A (both Motorola, both addressing dynamic voice/data allocation on a shared trunked channel — the closest to the '204 "switch the channel between voice and data" hook), then (3) WO 1989/011193 A1 / US 5,212,714 (E.F. Johnson — the closest to the '204 transmission format: data over an existing trunked voice channel with a detected dotting pattern and voice muting), then (4) US 4,837,858 A (Motorola — the subscriber‑unit side).

Honest caveat: On the citation record and the passages I could retrieve, none of the cited references appears to anticipate any of the ten independent claims under § 102, because no single reference is shown to disclose the combined limitation that defines the invention — monitoring trunked channels, detecting the cessation of analog voice on a channel, and switching that channel's trunked group association from a voice group to a data group, plus (per the claim) the multi‑link communications controller and the claim‑specific added features. The Motorola and E.F. Johnson references are better characterized as the strongest § 103 (obviousness) combination candidates than as § 102 anticipations. I could not obtain full text for every one of US 4,058,672, US 4,613,990, US 4,737,978, US 4,792,948, and US 5,022,024 within this session (search limits were reached), so that conclusion is strongest for the references I did read in full text and should be treated as preliminary for the others. For a definitive element‑by‑element § 102 chart, the remaining references' full texts (and the original examiner's file‑wrapper rejections) should be pulled from USPTO Patent Center / the published PDFs cited above.

I'll ground the analysis by checking what the key cited references actually disclose, since the prior-art section gives me mostly titles. Let me verify the closest references.

I have strong grounding on the two closest references. Let me verify two more cited references to avoid over-claiming.

Obviousness Analysis — U.S. Patent No. 5,282,204 under 35 U.S.C. § 103

Scope, sources, and caveats (read first). This analysis builds on the claim summary already generated and does not repeat it. I worked from the cited-art list in the Patent Citations / Non-Patent Citations sections of the Google Patents record (https://patents.google.com/patent/[US5282204](/patent/US5282204)/en). I obtained full-text/abstract confirmation for the two closest references — WO 1988/008648 A1 (and its U.S. counterpart US 4,831,373) and US 4,837,858 — plus abstracts for the two non-patent references (Stern; Bustillo et al.). For the remaining cited references I have only titles and, in a few cases, corroborating search snippets; I flag where a disclosure is not confirmed. I did not verify the full text of GB 2,217,149 or US 5,022,024, so I treat them as secondary/background art rather than load-bearing references. Patentability conclusions are the examiner's to draw; this is a technical § 103 prediction, not a legal opinion. I also note and preserve the claim-text transcription artifacts ("data base unit," "available ratio channel," "associated wit," "communicated wit") as they appear in the record; they appear to be OCR artifacts and do not change the claimed subject matter.

I. Legal framework applied

The controlling standard is Graham v. John Deere Co., 383 U.S. 1 (1966) (scope/content of prior art; differences; PHOSITA level; secondary considerations), as refined by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007) (a combination of familiar elements according to known methods is obvious when it yields predictable results; a "finite number of identified, predictable solutions" makes the combination obvious to try; design incentives and market pressure support motivation). Where a claim recites a numerical or parametric choice, In re Aller / In re Boesch control — routine optimization of a known parameter is obvious absent unexpected results. Critically, the patent's own specification admissions count as evidence that subject matter was known (§ 103; In re Nomiya).

II. Level of ordinary skill (PHOSITA)

A person of ordinary skill as of the April 13, 1992 priority date would have: a B.S. in electrical engineering (or equivalent) plus roughly 2–4 years in land-mobile/trunked radio systems, with working familiarity with (a) trunked channel-assignment protocols (the patent itself names E.F. Johnson "Logic Trunked Radio" and the Motorola trunking/signalling-word scheme, ISW/OSW), (b) analog FM voice repeaters and squelch/unmute logic, (c) radio data modems, packet framing, synchronization words and error correction, and (d) the OSI stack / RPC conventions. This is the skill level against which the combinations below are judged.

III. The common claim core

As noted in the prior summary, all ten independent claims (1, 2, 5, 7, 11, 12, 13, 16, 18, 22) share one core: a communications controller monitors trunked channels, detects a channel free of analog voice, switches that channel's trunked-group association from a "voice" group to a "data" group, and transfers data packets over it. Each independent claim then adds exactly one distinct feature (muting; sync pattern; ACK; RPC/OSI; diagnostics). This architecture makes the § 103 analysis tractable: if the core is obvious, each independent claim rises or falls on its one added feature.

IV. The core is obvious over the cited art

A. The best primary combination

WO 1988/008648 A1 (Motorola, Zdunek) + US 4,837,858 (Motorola) — and, alternatively, either paired with Stern (NPL).

• WO 1988/008648 A1 ("Method for dynamically allocating data channels on a trunked communication system," https://patents.google.com/patent/WO1988008648A1/en) discloses, per its abstract and specification: monitoring data activity during a predetermined interval; reserving an additional channel for data use when activity exceeds a maximum; reallocating a data channel back to voice when data traffic is low; repeaters that are each "capable of operating as a voice channel, control channel, or data channel"; and a network controller that requests allocation of a data channel from the central controller. That is the dynamic voice/data reassignment of pooled trunked channels — the essence of the claimed core, in the same field, by the same assignee. Its stated motivation (spectral efficiency; avoiding permanently dedicated data channels) is the very motivation the '204 patent recites.
• US 4,837,858 ("Subscriber unit for a trunked voice/data communication system," https://patents.google.com/patent/[US4837858A](/patent/US4837858A)/en) discloses a trunked voice/data subscriber that operates in either a voice mode or one of three data modes, transitions between modes (including when there is "no data activity for a predetermined time interval"), receives a "data channel grant which identifies a particular communication channel as a data channel," and monitors an assigned data channel. This supplies the per-channel/ per-subscriber mode-and-group switching and the "detect cessation → move to data" behavior.
• Stern, "An Improved Integrated Voice/Data Mobile Radio System," 40th IEEE VTC, May 1990, pp. 311–316 (confirmed abstract: https://ieeexplore.ieee.org/document/[110339](/patent/110339)) discloses adding data capability to a voice-only mobile radio system without requiring additional radio channels, using "packetized data, voice dedicated (PDVD)" burst switching that transmits data during the silent periods in the speech, with simulation showing the upgrade is feasible. This is a direct teaching of overlaying data on a voice channel during voice idle time, and it supplies an explicit motivation (added data capacity with no new spectrum).

Motivation to combine (KSR): (i) WO '648 and US '858 are Motorola references in the identical technological field sharing a common specification framework and even common terminology (ISW/OSW, control channel, master data channel) — In re Kahn/KSR "same field, common problem." (ii) Both primary references expressly motivate dynamic voice/data channel sharing for spectral efficiency. (iii) Stern supplies the recognized desirability of overlaying data onto a voice system's idle capacity and even analyzes it by simulation. A PHOSITA would predictably combine dynamic channel reassignment ('648/'858) with overlay-during-idle (Stern) to obtain the claimed core, with no unexpected result.

B. The core's "trigger" (cessation of voice) and "group association" mechanism

Stern's premise — data goes into the speech silence gaps — discloses the "upon cessation of transmission of analog voice information" trigger. US '858's mode transitions on "no data activity for a predetermined time interval" confirms that activity-based triggering of channel mode changes was routine. The residual question is whether the cited art literally frames this as "switching the trunked channel group association" (i.e., re-designating group membership) rather than controller-level reallocation. On the record here, WO '648's "each repeater … capable of operating as a voice channel, control channel, or data channel" plus its reallocation logic is the functional equivalent a PHOSITA would readily adapt; and US '858's "operate on a data channel … until commanded" supplies the mode/group reassignment. Flag: because I confirmed WO '648 only from its abstract/spec excerpts and not a line-by-line mapping to "group association," a patentee could argue a gap here; but the combination with '858 and Stern closes it, and this is a labeling distinction, not a technical one.

C. Corroborating art

• Bustillo et al., "DATAMOVIL: a practical implementation of TRADAMO mobile data transmission protocol," IEEE 39th VTC, May 1989, pp. 31–37 (https://ieeexplore.ieee.org/abstract/document/40046) teaches digital data transmission between mobiles and host computers over a mobile radio system, reducing air time, with a protocol and ASIC and error handling for mobile-channel error bursts. Combined with a trunked voice system, it teaches the "transfer data packets … between a host and mobiles" half of the core.
• US 4,058,672 (ITT) (https://patents.google.com/patent/US4058672) confirms that packet data with a synchronization/header and an error-checking code, store-and-forward, was old.
• Supplemental (not in the cited list — flagged): Motorola, "Integrating secure communications into 800 MHz trunked systems," 37th IEEE VTC, June 1987, teaches sensing digital data on a voice channel and switching the repeater between the analog voice mode and a digital data mode ("The instantaneous mode of the voice channel at any time is determined by whether or not received data is sensed on the channel"), plus mobile muting/unmuting gated by detection of low-speed data. I include it only as corroboration because it lies outside the record's prior-art section; it is nonetheless a powerful pre-1992 datapoint on the voice/data mode-switch and muting.

Conclusion on the core: the shared subject matter of independent claims 1, 2, 5, 7, 11, 12, 13, 16, 18 and 22 is prima facie obvious over WO '648 + US '858 + Stern (optionally + Bustillo).

V. Claim-by-claim on the added limitations

VI. Recommended rejection combinations

1. Core + claims 1/12: WO 1988/008648 A1 in view of US 4,837,858, further in view of Stern (1990). (Optionally add Bustillo for the host↔mobile data path.)
2. Claims 2–4 / 13–15: #1 further in view of US 4,058,672 (packet sync/header/error-checking) and/or WO 1989/011193 (E.F. Johnson data interface).
3. Claims 5–6 / 16–17: #2 further in view of Bustillo (DATAMOVIL error handling) and general ARQ/backoff knowledge.
4. Claims 7–10 / 18–21: #1 in view of the applicant's own admission that RPC/OSI are known.
5. Claims 11 / 22: #1 in view of Stern (simulation methodology) and Bustillo (diagnosis/supervision).

VII. Weaknesses, counterarguments, and what would change the analysis

• Strongest patentee rebuttal: the specific sync code of claim 4/15. A patentee can argue the exact hex string is an arbitrary, unrecognized selection. Realistically, though, it is routine optimization, and the claim is so narrow it invites design-around; it also cannot rescue the independent claims.
• "Group association" labeling: if the examiner/patentee insists that WO '648 allocates channels at the controller but does not re-associate a channel's group membership, the combination with US '858 (subscriber mode/group switching) is needed to fill the gap. I could not confirm WO '648's exact wording on this point.
• Secondary considerations: none are in the record — no evidence of commercial success, long-felt need, or nexus was found in the previously generated sections. The later same-assignee US 5,548,805 ("spectral overlay") shows the field was actively developed, but it is after the '204 priority date and therefore is not prior art and does not create a nexus for the '204 claims.
• Do not over-read the unverified references. I did not confirm the disclosures of GB 2,217,149 or US 5,022,024; they are cited as background/analogous art only and are not needed for any rejection above.

VIII. Bottom line

Every claim of US 5,282,204 is prima facie obvious under § 103. The patent essentially (a) applied well-known trunked voice/data channel-reallocation (WO '648 / US '858 / US '813,373 lineage) and (b) applied well-known data-overlay-during-voice-idle (Stern) to put packet data on idle trunked channels — using standard elements (sync/preamble codes, ARQ with backoff, RPC over OSI, simulation-based tuning) that the specification itself describes as known. Under KSR, the combination is the predictable arrangement of familiar elements motivated by the same spectral-efficiency and capacity concerns the references themselves articulate. The only claim with a colorable non-obviousness argument is claim 4/15 (the exact hex sync code), and even that is likely routine optimization — and too narrow to be commercially meaningful.

Confidence: high on the core analysis and the claim mapping (based on the authoritative full text plus confirmed abstracts of WO '648, US '858, Stern, and Bustillo); moderate on any characterization resting on titles alone; low on any assertion about GB 2,217,149 or US 5,022,024, which I did not verify and did not rely upon.