Patents Assigned to SIRF Technology
  • Patent number: 6707423
    Abstract: The present invention discloses methods, apparatuses, and systems for eliminating auto- and cross-correlation in weak signal CDMA systems, such as GPS systems. The invention uses parallel data paths that allow standard correlation of signals in parallel with verification of the lock signal to determine whether the system has locked onto the proper signal within the scanned signal window. The invention can be made with multiple CPUs, a single CPU with dual input modes, on multiple IC chips, or as a single IC chip solution for small, low cost reception, downconversion, correlation, and verification systems.
    Type: Grant
    Filed: September 16, 2002
    Date of Patent: March 16, 2004
    Assignee: SiRF Technology, Inc.
    Inventors: Gregory Bret Turetzky, Charles P. Norman, Henry D. Falk
  • Patent number: 6703971
    Abstract: The present invention discloses a system for determining the position of a GPS terminal. The system comprises a GPS terminal, a location aiding server, and a communications system. Messages are passed between the GPS terminal and the server, as well as within the GPS terminal, to determine the mode of operation of the GPS portion of the system. Decisions are made based on availability of aiding data and Quality of Service requirements.
    Type: Grant
    Filed: February 21, 2002
    Date of Patent: March 9, 2004
    Assignee: SiRF Technologies, Inc.
    Inventors: Ashutosh Pande, Lionel J. Garin, Chiayee S. Chang, Gengsheng Zhang, Randall J. Silva
  • Patent number: 6691066
    Abstract: The present invention discloses a method and an apparatus for improving measurement fault detection in a sequential measurement processing estimator, and is particularly applied to Global Positioning Receivers.
    Type: Grant
    Filed: August 28, 2001
    Date of Patent: February 10, 2004
    Assignee: SiRF Technology, Inc.
    Inventor: Keith Jacob Brodie
  • Patent number: 6684158
    Abstract: A Search Domain Reducing Frequency Transfer in A Multi-Mode Global Positioning System Used With Wireless Networks is disclosed.
    Type: Grant
    Filed: May 22, 2002
    Date of Patent: January 27, 2004
    Assignee: SiRF Technology, Inc.
    Inventors: Lionel Jacques Garin, Leon Kuo-Liang Peng, Gengsheng Zhang, Nicolas Patrick Vantalon
  • Patent number: 6680695
    Abstract: The present invention discloses methods, apparatuses, and systems for eliminating auto- and cross-correlation in weak signal CDMA systems, such as GPS systems. The invention uses parallel data paths that allow standard correlation of signals in parallel with verification of the lock signal to determine whether the system has locked onto the proper signal within the scanned signal window. The invention can be made with multiple CPUs, a single CPU with dual input modes, on multiple IC chips, or as a single IC chip solution for small, low cost reception, downconversion, correlation, and verification systems.
    Type: Grant
    Filed: July 20, 2001
    Date of Patent: January 20, 2004
    Assignee: Sirf Technology, Inc.
    Inventors: Gregory Bret Turetzky, Charles P. Norman, Henry D. Falk
  • Patent number: 6680703
    Abstract: The present invention provides methods and apparatuses for tuning a circularly polarized patch antenna to compensate for manufacturing tolerance variation, and to compensate for mistuning of the antenna due to the implementation of the product in which the antenna is used. Varactors are coupled to the metal patch portion of the antenna, and a dc voltage is applied to tune the antenna capacitance. The varactors can receive different voltages if desired.
    Type: Grant
    Filed: February 14, 2002
    Date of Patent: January 20, 2004
    Assignee: SiRF Technology, Inc.
    Inventor: Richard Joseph McConnell
  • Patent number: 6675003
    Abstract: In a system and method for simultaneously receiving or switching between dual frequency carrier signals in a GPS receiver is adapted to utilize different harmonics of a sub-harmonic frequency generator, which may include a lower frequency voltage controlled oscillator (VCO) to detect the L1 and L2 GPS carriers. A sub-harmonic mixer may be used to simultaneously down convert the L1 and L2 signals to a lower intermediate frequency (IF). A second mixer may be an image reject (IR) mixer used to separate the downconverted second L2 signals. This mixer may be configured to simultaneously monitor the L1 and L2 signals, or to switch between the L1 and L2 signals. High frequency switching is not required of the radio frequency (RF) input or local oscillator signals, and simultaneous L1 and L2 reception is enabled without a 3 dB image noise degradation. This method minimizes the RF components and power dissipation in a dual frequency GPS receiver, while optimizing the functionality and performance.
    Type: Grant
    Filed: December 7, 2000
    Date of Patent: January 6, 2004
    Assignee: SiRF Technology, Inc.
    Inventors: Noshir B. Dubash, Robert Tso
  • Patent number: 6671620
    Abstract: In a satellite global positioning system, satellite acquisition and location assistance is based upon shared information between a GPS receiver and a remote server. Satellite position is predicted by satellite almanac data.
    Type: Grant
    Filed: May 18, 2000
    Date of Patent: December 30, 2003
    Assignee: SIRF Technology, Inc.
    Inventors: Lionel Jacques Garin, Kurt Christian Schmidt
  • Publication number: 20030234738
    Abstract: Generic SATPS receivers and methods for configuring generic SATPS receivers that include a plurality of outputs are provided. These configurable SATPS receivers are adapted to be utilized in at least one of a plurality of particular SATPS receiver applications, and can also include a plurality of input paths, and a means for generating selected ones of the plurality of possible outputs. Selected ones of the plurality of outputs are enabled/disabled based on at least one requirement of the particular receiver application to configure or program the generic SATPS receiver to function as a SATPS receiver used for a particular SATPS receiver application or operating environment. The selected ones of the plurality of outputs can be defined by and can be those utilized by the particular SATPS receiver application or operating environment.
    Type: Application
    Filed: June 20, 2002
    Publication date: December 25, 2003
    Applicant: SiRF Technology, Inc.
    Inventors: Anthony James Orler, Keith Jacob Brodie, Charles P. Norman
  • Publication number: 20030234739
    Abstract: Generic SATPS receivers and methods for configuring generic SATPS receivers that include a plurality of outputs are provided. These configurable SATPS receivers are adapted to be utilized in at least one of a plurality of particular SATPS receiver applications, and can also include a plurality of input paths, and a means for generating selected ones of the plurality of possible outputs. Selected ones of the plurality of outputs are enabled/disabled based on at least one requirement of the particular receiver application to configure or program the generic SATPS receiver to function as a SATPS receiver used for a particular SATPS receiver application or operating environment. The selected ones of the plurality of outputs can be defined by and can be those utilized by the particular SATPS receiver application or operating environment.
    Type: Application
    Filed: June 20, 2002
    Publication date: December 25, 2003
    Applicant: SiRF Technology, Inc.
    Inventors: Anthony James Orler, Keith Jacob Brodie, Charles P. Norman
  • Patent number: 6665612
    Abstract: A method for navigation processing in a satellite positioning system receiver is disclosed. A method in accordance with the present invention comprises separating the three SATPS satellites into a first pair and a second pair, constructing a primary solution and an alternate solution, wherein the primary solution and the alternate solution satisfy the measurement constraints, computing a Doppler difference estimate for the primary solution and a Doppler difference estimate for the alternate solution, computing Doppler difference residuals for the first pair and the second pair of SATPS satellites, and comparing the Doppler difference residuals for said primary and alternate solutions to determine a valid solution. Typically, the computing of a Doppler difference residuals comprises differencing a measured Doppler difference from an estimated Doppler difference for the first pair and the second pair of SATPS satellites.
    Type: Grant
    Filed: August 29, 2001
    Date of Patent: December 16, 2003
    Assignee: SiRF Technology, Inc.
    Inventors: Keith Jacob Brodie, David Allan Tuck, Mangesh M. Chansarkar
  • Patent number: 6662107
    Abstract: Power is conserved in a Global Positioning System (GPS) receiver by shutting down selected components during periods when the GPS receiver is not actively calculating the GPS receiver location. A low power time keeping circuit accurately preserves GPS time when the selected components are deactivated. When the selected components are turned on in response to a wake-up command, time provided from the low power time keeping circuit, corrected for actual operating temperatures, and data from the GPS clock temperature/frequency table, are used to recalibrate time from a GPS oscillator. Positions of the GPS satellites are then estimated such that the real GPS time is quickly determined from the received satellite signals. Once real GPS time is determined from the detected satellite signals, the selected components are deactivated. The process described above is repeated such that accurate GPS time is maintained by the low power time keeping circuit.
    Type: Grant
    Filed: October 30, 2001
    Date of Patent: December 9, 2003
    Assignee: SiRF Technology, Inc.
    Inventor: Steven A. Gronemeyer
  • Patent number: 6650879
    Abstract: The invention is directed to a personal telecommunications device having both global positioning systems (GPS) and telecommunications provisions which share a common clock source. GPS provisions include a feedback loop for controlling an oscillator that generates a GPS system signal based upon the common clock signal. The feedback loop includes a frequency synthesizer for generating a feedback control signal, a phase comparator for generating a control signal in accordance with the feedback signal and the common clock signal, and a loop filter for processing and outputting the control signal to the oscillator to control the frequency of GPS system signals.
    Type: Grant
    Filed: April 18, 2000
    Date of Patent: November 18, 2003
    Assignee: SiRF Technology, Inc.
    Inventor: Paul A. Underbrink
  • Patent number: 6643587
    Abstract: A navigation system for tracking the position of an object includes a GPS receiver responsive to GPS signals for periodically providing navigation state measurement updates to a navigation processor. The system also includes a dead-reckoning sensor responsive to movement of the object for providing movement measurements to the navigation processor. The navigation processor determines object navigation states using the navigation state measurement updates and propagates the object navigation states between measurement updates using the movement measurements.
    Type: Grant
    Filed: February 26, 2002
    Date of Patent: November 4, 2003
    Assignee: SiRF Technology, Inc.
    Inventors: Keith J. Brodie, Stephen F. Rounds, Mangesh M. Chansarkar
  • Patent number: 6636178
    Abstract: A signal detector is provided in which correlation analyses of multiple segments of a received signal from separate and distinct periods of time are combined to improve the detection capability of the signal detector. In one embodiment, the signal detector is part of a GPS receiver.
    Type: Grant
    Filed: October 4, 2001
    Date of Patent: October 21, 2003
    Assignee: SiRF Technology, Inc.
    Inventor: Steven A. Gronemeyer
  • Patent number: 6633814
    Abstract: A terrestrial C/A code GPS receiver system digitally samples, filters and stores a segment of 11 half chips of the received composite as a binary number and multiplexes this number for parallel correlation with each of a series of multibit code replicas for the satellites to be tracked. Each of the time delay specific correlation products are accumulated in a cell of a memory matrix so that at least twenty two delays for each satellite may be evaluated each code period providing fast reacquisition, even within a city intersection, as well as correction of multipath tracking and multipath interference. All cells of the memory matrix may be used for a acquisition of a single satellite in about 4 ms. Two satellite tracking, in addition to altitude hold, uses cross track hold alternating with clock hold to update the cross track estimate. Single satellite tracking uses cross track and clock hold together. Navigation data is updated with detected changes in motion including turns.
    Type: Grant
    Filed: December 22, 2000
    Date of Patent: October 14, 2003
    Assignee: SiRf Technology, Inc.
    Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
  • Patent number: 6618670
    Abstract: The invention describes methods and apparatuses for determining a user position based on a minimization of the errors introduced into the GPS system because of clock bias, noise, multipath, or other uncertainties. By overdetermining position, for example, clock biases can be removed from the system.
    Type: Grant
    Filed: September 14, 2001
    Date of Patent: September 9, 2003
    Assignee: SIRF Technology, Inc.
    Inventor: Mangesh M. Chansarkar
  • Patent number: 6611757
    Abstract: A system for determining the location of an object includes an interrogator remote from the object and a transponder located at the object. The interrogator receives GPS signals and transmits pre-positioning data and a tracking signal to the transponder. The pre-positioning data includes pseudorandom noise (PRN) code number, Doppler frequency offset and code phase offset while the tracking signal includes reference time and frequency information. The transponder collects RF samples of at least one of the GPS signals associated with one of the PRN code numbers and correlates the RF samples of the GPS signal against code replicas of the GPS signal based on the Doppler frequency offset, code phase offset and reference time and frequency information for that GPS signal to produce the correlation snapshot. The transponder transmits the correlation snapshot to the interrogator and the interrogator determines the pseudorange associated with the GPS signal using the correlation snapshot.
    Type: Grant
    Filed: May 28, 2002
    Date of Patent: August 26, 2003
    Assignee: SiRF Technology, Inc.
    Inventor: Keith J. Brodie
  • Patent number: 6606349
    Abstract: Embodiments of the invention are used to improve performance of spread spectrum communications equipment. The improvement may take the form of improved sensitivity to weak signals, quicker acquisition time of weak signals, or the reduction of multipath interference. To acquire a spread spectrum signal PN codes are commonly compared with the spread spectrum signal. This comparison is often in reality a successive series of comparisons with the same code. Successive comparisons are often carried out in a process called hypothesis testing by which the correlated output of the spread spectrum signal and the PN code must pass a series of thresholds. This method is adopted to prevent identifying a PN code as being present based on a spurious correlation value. This method of successive comparisons also prevents a low correlated value from being rejected immediately thereby helping assure that signals with low signal strength can be identified also.
    Type: Grant
    Filed: February 4, 1999
    Date of Patent: August 12, 2003
    Assignee: SiRF Technology, Inc.
    Inventors: Shridhara A. Kudhrethaya, Paul A. Underbrink
  • Patent number: 6597988
    Abstract: The invention comprises a set of pseudolites deployed throughout an area of interest in which the GPS constellation visibility may be limited, such as in and around some high-rise buildings in an urban setting, and a database of these installed pseudolite locations with their PRN numbers indexed by cell-site. When the cellular telephone is in communication with a particular tower or transceiver, the PRN numbers of all local psuedolites are transmitted to the cellular telephone. If the cellular telephone has a position solution which has been transmitted to the cell tower, prepositioning information for a code search can be transmitted to the phone as well. The phone can then augment the phone's normal acquisition list with the psuedolites in the area and track the pseudolites to augment navigation capabilities in a harsh environment.
    Type: Grant
    Filed: September 21, 2001
    Date of Patent: July 22, 2003
    Assignee: SiRF Technology, Inc.
    Inventors: Keith Jacob Brodie, David Allan Tuck