Pulse or digital communications – Spread spectrum – Direct sequence
Reexamination Certificate
2001-08-16
2003-03-11
Pham, Chi (Department: 2631)
Pulse or digital communications
Spread spectrum
Direct sequence
C342S357490
Reexamination Certificate
active
06532251
ABSTRACT:
FIELD OF THE INVENTIONS
The present inventions relate generally to spread spectrum receivers and methods, and more particularly to data message bit synchronization of spread spectrum signals having repeating sequences of pseudorandom code bits modulated with data message bits.
BACKGROUND OF THE INVENTIONS
Satellite based positioning system enabled receivers, for example Global Positioning System (GPS) receivers, are used widely for navigation and have substantial potential to provide location information in mobile wireless communication devices, including cellular telephones, which must soon comply with United States Federal Communications Commission E-911 location requirements.
One of the foremost interesting specifications of a GPS receiver is the time required to acquire satellite signals, known as spread spectrum pseudorandom noise (PN) codes and to provide position coordinates after power is applied to the receiver. The time required to perform these operations is known as the time-to-first-fix (TTFF), which is determined generally by the hardware and software architecture of the receiver.
In battery powered hand-held GPS receivers, including those embedded in cellular telephones, the acquisition time influences total battery life since the receiver is powered continuously during location determination. The time required to generate a location fix is also important in emergency location applications, for example in E-911 enabled cellular telephones. Another important consideration, particularly in hand-held GPS receivers, is the time to acquire signals in weak signal environments, for example in environments where the signal is obstructed by foliage, automobiles, urban canyons and buildings.
It is known to search the code phase space for a single satellite in parallel. U.S. Pat. No. 6,009,118 to Tiemann, for example, discloses 2046 parallel correlators that search all phase delays for a single satellite. In “Real Time Missile Tracking”, Proceedings of the ION Aerospace Meeting”, April 1981, Wells describes a flash parallel correlator that computes correlation parameters for as many as 64 different phase delays of a single satellite. In these and other known parallel correlation schemes, a correlator block is assigned to search for one satellite over a pre-determined number of phase delays. In both Tiemann and Wells, however, the correlator block searched only for one satellite at a time. In these and other prior art systems, satellite signal searching remains a sequential process, wherein the parallel processing applies only to the phase delays for the particular satellite being searched. In Tiemann and Wells, searching or detecting more than one satellite in parallel requires duplication of the parallel correlators.
Other examples of parallel correlators are described in U.S. Pat. No. 5,901,171 to Kohli, and U.S. Pat. No. 6,208,291 to Krasner. In these patents a parallel correlator circuit is duplicated N times in order to search for N satellites.
In some applications, the satellite signal receiver has knowledge of the visible satelites, their approximate Doppler frequency, and in some cases, the approximate phase delay and phase/polarity of the 50 bits per second (BPS) navigation message bits. This knowledge can come from locally stored ephemeris, almanac, approximate position, and time, or from other sources, for example, the IS-801 specification provides satellite visibility, Doppler, phase delay at a particular epoch time. Since there are generally 8-10 satellites visible at any one time, searching in parallel for these signals shortens the total acquisition time.
What is desired generally is an efficient spread spectrum signal searcher that substantially reduces the average TTFF in a manner that minimizes the number of gates/transistors and in some applications reduces power consumption.
REFERENCES:
patent: 4114155 (1978-09-01), Raab
patent: 4164036 (1979-08-01), Wax
patent: 4291409 (1981-09-01), Weinberg
patent: 4426712 (1984-01-01), Gorski-Popiel
patent: 4870422 (1989-09-01), Counselman
patent: 5043736 (1991-08-01), Darnell
patent: 5194871 (1993-03-01), Counselman
patent: 5343209 (1994-08-01), Sennott
patent: 5365450 (1994-11-01), Schuchman
patent: 5384574 (1995-01-01), Counselman
patent: 5600670 (1997-02-01), Turney
patent: 5663734 (1997-09-01), Krasner
patent: 5663735 (1997-09-01), Eshenbach
patent: 5757859 (1998-05-01), Retzer et al.
patent: 5841396 (1998-11-01), Krasner
patent: 5893044 (1999-04-01), King et al.
patent: 5901171 (1999-05-01), Kohli et al.
patent: 5917444 (1999-06-01), Loomis
patent: 5945944 (1999-08-01), Krasner
patent: 5982324 (1999-11-01), Watters
patent: 6002363 (1999-12-01), Krasner
patent: 6009118 (1999-12-01), Tiemann et al.
patent: 6041222 (2000-03-01), Horton
patent: 6061018 (2000-05-01), Sheynblat
patent: 6064336 (2000-05-01), Krasner
patent: 6088348 (2000-07-01), Bell
patent: 6097974 (2000-08-01), Camp
patent: 6107960 (2000-08-01), Krasner
patent: 6111540 (2000-08-01), Krasner
patent: 6121923 (2000-09-01), King
patent: 6122506 (2000-09-01), Lau
patent: 6133871 (2000-10-01), Krasner
patent: 6133873 (2000-10-01), Krasner
patent: 6133874 (2000-10-01), Krasner
patent: 6151353 (2000-11-01), Harrison et al.
patent: 6191731 (2001-02-01), McBurney et al.
patent: 6208290 (2001-03-01), Krasner
patent: 6208291 (2001-03-01), Krasner
patent: 6208292 (2001-03-01), Sih
patent: 6236354 (2001-05-01), Krasner
patent: 6389291 (2002-05-01), Pande et al.
patent: 6421002 (2002-07-01), Krasner
patent: 6427120 (2002-07-01), Garin et al.
patent: 6429809 (2002-08-01), Vayanos et al.
Charles C. Counselman III et al., Miniature Interferometer Terminals For Earth Surveying: Ambiguity and Multipath with Global Positioning System; IEEE Transactions on Geoscience and Remote Sensing; vol. GE-19, No. 4, Oct. 1981; pp. 244-252.
Charles C. Counselman III et al., The Macrometer: A Compact Radio Interferometry Terminal For Geodesy With GPS; Macrometrics, Inc.; pp. 1165-1172.
T. Thompson, Performance Of The Satrack/Global Positioning System Trident I Missile Tracking System; The Johns Hopkins University, Applied Physics Laboratory; 1980 IEEE; pp. 445-449.
Mikko Kokkonen, et al., A New Bit Synchronization Method for a GPS Receiver; 2002 IEEE; pp. 85-90.
Charles C. Counselman III et al., Accuracy of Baseline Determinations By Mites Assessed By Comparison With Tape, Theodolite and Geodimeter Measurements; EOS; vol. 62, No. 17; Apr. 28, 1981; p. 260.
Robert P. Denaro, Navstar GPS Test Results and Eric J. Hoffman, et al.; GPSPAC: A Spaceborne GPS Navigation Set; IEEE Plans 1978 Position Location and Navigation Symposium; Nov. 6-9, 1978; which includes the title page, Table of Contents, pp. 1-6 and pp. 13-20.
M. J. Bordel, et al., Texas Instruments Phase I GPS User Equipment; The Institute of Navigation, Global Positioning System; vol. 1, pp. 87-102.
Larry L. Horowitz, Analysis Of A Single-Bit Digital Receiver For Carrier And Code Tracking; The Johns Hopkins University—Applied Physics Laboratory; Jul. 1976, Copy No. 59, pp. 5-139.
B. G. Glazer, GPS Receiver Operation; Navigation Journal of the Institute of Navigation; vol. 25, No. 2, Spring 1978; pp. 173-178.
Charles C. Counselman III et al., Miniature Interferometer Terminals For Earth Surveying; Massachusetts Institute of Technology; pp. 139-163.
Charles C. Counselman III et al., Miniature Interferometer Terminals For Earth Surveying; Massachusetts Institute of Technology; pp. 65-85.
E. D. Holm and E. E. Westerfield, “A GPS Fast Acquisition Receiver”, IEEE 1983 National Telesystems Conference, Feb. 1983.
Geier George Jeffrey
King Thomas Michael
Strother Troy L.
Bowler II Roland K.
Motorola Inc.
Pham Chi
Tran Khai
LandOfFree
Data message bit synchronization and local time correction... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Data message bit synchronization and local time correction..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data message bit synchronization and local time correction... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3083366