US5557645A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Channel-independent equalizer device
Assignee: Unwired Planet LLC
•
Filing: 1994-09-14
•
Granted: 1996-09-17
•
Expires: 2014-09-14
Abstract
Abstract A demodulator for demodulating a signal modulated with digital information symbols so as to extract the information symbols is disclosed. A receiver receives a signal over a communications channel and samplers and digitizers produce a sequence of numerical sample values representative of the received signal. Memories are provided each having a number of state memories each associated with a hypothesized symbol string. A controller selectively retrieves values from the memory means and controls the timing of operations thereupon. A metric computer computes candidate metrics using a hypothesis of a next of the information symbols to be demodulated made by the controller, one of the numerical sample values, path metric values, B-matrices, and U-vectors and the candidate metrics associated state number selected by the controller from the memory means. A best predecessor computer determines the best of the candidate metrics to be selected to be written back into the memory means along with a successor B-matrix, U-vector and path history. The successor B-matrices, U-vectors and path history are then updated using corresponding values associated with the best predecessor and one of numerical sample values.
Inventors
- 👤 Paul W. Dent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:51
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03178; H04L25/03203
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
214 words
An apparatus for demodulating a signal modulated with digital information symbols so as to extract said information symbols, comprising: receiving means for receiving said signal over a communications channel; sampling and digitizing means for producing a sequence of numerical sample values representative of said received signal; memory means for storing said numerical sample values, said memory means having a number of state memories each associated with a hypothesized symbol string and each comprising: path metric memory, B-matrix memory, U-vector memory, and path history memory; control means for selectively retrieving values from said memory means and controlling the timing of operations thereupon; metric computing means for computing candidate metrics using a hypothesis of a next of said information symbols to be demodulated made by said control means, one of said numerical sample values, path metric values, B-matrices, and U-vectors and the candidate metrics associated state number selected by said control means from said memory means; best predecessor computation means for determining the best predecessor of said candidate metrics to be selected to be written back into said memory means along with a successor B-matrix, U-vector and path history; and updating means for calculating said successor B-matrices, U-vectors and path history using corresponding values associated with said best predecessor and said one of numerical sample values.
Claim 2
Independent Claim
214 words
An apparatus for demodulating a signal modulated with digital information symbols so as to extract said information symbols, comprising: receiving means for receiving said signal over a communications channel; sampling and digitizing means for producing a sequence of numerical sample values representative of said received signal; memory means for storing said numerical sample values, said memory means having a number of state memories each associated with a hypothesized symbol string and each comprising: path metric memory, B-matrix memory, U-vector memory, and path history memory; control means for selectively retrieving values from said memory means and controlling the timing of operations thereupon; metric computing means for computing candidate metrics using a hypothesis of a next of said information symbols to be demodulated made by said control means, one of said numerical sample values, path metric values, B-matrices, and U-vectors and the candidate metrics associated state number selected by said control means from said memory means; best predecessor computation means for determining the best predecessor of said candidate metrics to be selected to be written back into said memory means along with a successor B-matrix, U-vector and path history; and updating means for calculating said successor B-matrices, U-vectors and path history using corresponding values associated with said best predecessor and said one of numerical sample values.
Claim 3
Dependent Claim
17 words
The demodulating apparatus according to claim 1, wherein said receiving means is connected to a telephone line.
Claim 4
Dependent Claim
21 words
The demodulating apparatus according to claim 1, wherein said receiving means is a radio receiving means equipped with a radio antenna.
Claim 5
Dependent Claim
20 words
The demodulating apparatus according to claim 3, wherein said receiving means is used in a cellular radio telephone subscriber unit.
Claim 6
Dependent Claim
20 words
The demodulating apparatus according to claim 3, wherein said receiving means is used in a cellular radio network base station.
Claim 7
Dependent Claim
23 words
The demodulating apparatus according to claim 1, wherein said U-vectors are modified before use in said metric computing means and said updating means.
Claim 8
Dependent Claim
21 words
The demodulating apparatus according to claim 6, wherein said U-vectors are modified by scaling down said U-vectors by a predetermined factor.
Claim 9
Dependent Claim
23 words
The demodulating apparatus according to claim 1, wherein said B-matrices are modified before use in said metric computing means and said updating means.
Claim 10
Dependent Claim
21 words
The demodulating apparatus according to claim 8, wherein said B-matrices are modified by scaling up said B-matrices by a predetermined factor.
Claim 11
Dependent Claim
20 words
The demodulating apparatus according to claim 8, wherein said B-matrices are modified by adding a constant matrix to said B-matrices.
Claim 12
Dependent Claim
16 words
The demodulating apparatus according to claim 10, wherein said constant matrix has only non-zero diagonal elements.
Claim 13
Dependent Claim
16 words
The demodulating apparatus according to claim 1, wherein said signal is modulated by binary information bits.
Claim 14
Dependent Claim
15 words
The demodulating apparatus according to claim 12, wherein said signal is modulated using Phase-Reverse Keying.
Claim 15
Dependent Claim
15 words
The demodulating apparatus according to claim 12, wherein modulation changes the phase of said signal.
Claim 16
Dependent Claim
18 words
The demodulating apparatus according to claim 12, wherein said signal is modulated using offset quadrature phase shift keying.
Claim 17
Dependent Claim
15 words
The demodulating apparatus according to claim 1, wherein said signal is modulated with quaternary symbols.
Claim 18
Dependent Claim
17 words
The demodulating apparatus according to claim 16, wherein said signal is modulated using Quadrature Phase Shift Keying.
References Cited (Backward Citations)
US5119400A
Cited
US5131011A
Cited
EP0425458A1
Cited
US5164961A
Cited
US5199047A
Cited
US5307374A
Cited
US5331666A
Cited
EP0594551A1
Cited
US5335250A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-09-17 | 2000-03-18 | 2000-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-09-17 | 2004-03-18 | 2004-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-09-17 | 2008-03-18 | 2008-09-17 | $7700.00 | Window Closed / Lapsed |