Invalidity dossier
US 5511098
Digital methods and apparatus reverse link signal detection and recovery in a mobile data base station
Current assignee: Cirrus Logic Inc
Added 9/23/2026, 6:36:43 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
US5511098A — Digital methods and apparatus reverse link signal detection and recovery in a mobile data base station
- Inventor: Steven H. Gardner
- Original assignee: Pacific Communication Sciences, Inc. (later records list ADC Telecommunications Inc./ADC Mobile Systems, Inc.; current assignee listings include Cirrus Logic Inc. and Commscope Connectivity LLC)
- Priority/filing date: 1993-11-12; grant/publication: 1996-04-23; anticipated expiration: 2013-11-12; status: Expired – Lifetime
- Application: US08/152,198
Purpose. The patent addresses signal detection and recovery in a Cellular Digital Packet Data (CDPD) Mobile Data Base Station (MDBS) sharing AMPS cellular channels. CDPD uses in-band FSK signaling and Digital Sense Multiple Access, under which subscriber units transmit only when they have data, beginning with a 38-bit dotting sequence (alternating ones and zeroes; phase changes nominally ±90°, actually closer to ±54° due to GMSK intersymbol interference), followed by a 22-bit synchronization signal and roughly 385 data bits. The stated purpose is to provide coarse/fine frequency correction for RF down conversion, dotting-sequence detection, and establishment and maintenance of receiver timing, with some techniques also useful in subscriber units for forward-link communication. The invention further allows detection of an arbitrary or random data stream, as the CDPD System Specification requires—pure dotting-sequence correlation alone being inadequate for that.
Plain-language scope. The received signal is frequency downshifted by multiplying it by inphase and quadrature components of a local carrier oscillator; the resulting signal-vector components are sampled and digitized at more than twice the expected bit rate. Difference vectors between digitized downshifted signal vectors one expected bit time apart are determined and examined to detect the dotting sequence and estimate carrier frequency error, which on detection initially corrects the stored vectors. Bit timing is then recovered by using samples taken near the expected bit transitions.
What the excerpt does not establish. The provided text is partial; it omits full claim language, detailed description, drawing contents, and the specific 22-bit synchronization code. It does not establish validity, enforceability, litigation history, or prior art beyond a brief reference to the CDPD System Specification.
Source: https://patents.google.com/patent/[US5511098](/patent/US5511098)/en
Generated 10/1/2026, 9:42:40 PM
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PTAB challenges
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Assignment history
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Prior art
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