Patents Assigned to Enuvis, Inc.
  • Publication number: 20030197641
    Abstract: A method in a Global Positioning System (GPS) receiver achieves enhanced performance by scheduling searches in the Doppler search space according to a cost function. The cost function relates to both the cost of building a 3-dimensional correlation grid and the cost of searching satellite, code phase, Doppler and integration time interval spaces for values that provide a maximum in the correlation grid. In one embodiment, after the clock Doppler is determined upon acquiring one satellite, the Doppler search range associated with a cell in the grid is dominated by the receiver's own motion. The scheduler schedules searching of the Doppler search space using search ranges determined empirically by the expected receiver velocity. In one embodiment, the scheduler increases integration times before changing Doppler search ranges, which require a recalculation of the grid.
    Type: Application
    Filed: April 19, 2002
    Publication date: October 23, 2003
    Applicant: Enuvis, Inc.
    Inventors: Jesse Stone, Andrew Chou, Wallace Mann
  • Publication number: 20030197638
    Abstract: In a mobile communication device, a method for compensating for a frequency adjustment in an oscillator shared between a communication circuit and a positioning signal receiver is provided. In one embodiment, the method begins to receive and store a positioning signal at a first time point. When, at a second time point, the operating frequency of the shared oscillator is adjusted, the frequency adjustment is recorded. After the positioning signal is completely received and stored, the processing of the positioning signal takes into consideration the frequency adjustment. In that embodiment, the processing hypothesizes a frequency shift in the received positioning signal. According to another aspect of the present invention, a method for determining the operating frequency of an oscillator detects a beginning time point of a reference signal received by the mobile communication device and enables a counter to count in step with a clock signal derived from the oscillator.
    Type: Application
    Filed: April 19, 2002
    Publication date: October 23, 2003
    Applicant: Enuvis, Inc.
    Inventors: L. Scott Bloebaum, Piyush Bharti, Sherk Chung, Benjamin Van Roy, Wallace Mann
  • Patent number: 6542116
    Abstract: To determine the clock doppler of a signal receiver, sampled data received from a receiver into are divided into data segments of incremental length. The clock doppler is estimated based on correlating each data segment with the expected signal from each satellite, from a set of satellites, that is overhead the receiver. For each data segment, the correlated result of each satellite is used to refine subsequent calculations of the clock doppler of the next overhead satellite. When the clock doppler calculations for a data segment have been performed using all overhead satellites from the set of satellites, then the results for that data segment are used to refine the calculations for the next data segment.
    Type: Grant
    Filed: June 22, 2001
    Date of Patent: April 1, 2003
    Assignee: Enuvis, Inc.
    Inventors: Anant Sahai, Andrew Chou, Wallace Mann, Stefano Casadei
  • Patent number: 6535163
    Abstract: To determine the location of a signal receiver, sampled data received from a receiver is divided into data segments of increasing length. Current ranges for a delay value and for a modulation frequency value are calculated relative to each satellite signal source that is overhead the signal receiver. Using the data segments of increasing length, the current ranges, estimates for the delay value and for the modulation frequency value are then iteratively calculated and updated. For each signal source, I and Q correlation integrals and their magnitude values are calculated using the modulation frequency value estimate and each of a range of delay values centered around the delay value estimate. The resulting magnitude-curve is interpolated using the calculated magnitude values. The location of the receiver is calculated using the shape of the magnitude-curve to represent the I and Q correlation integrals for each signal source.
    Type: Grant
    Filed: June 22, 2001
    Date of Patent: March 18, 2003
    Assignee: Enuvis, Inc.
    Inventors: Anant Sahai, John Tsitsiklis, Benjamin Van Roy, Andrew Chou, Wallace Mann, Jesse Robert Stone, Wungkum Fong
  • Patent number: 6525688
    Abstract: Some embodiments of the invention provide a location-determination system that includes several transmitters and at least one receiver. Each transmitter transmits a signal that includes a unique periodically-repeating component, and the receiver receives a reference signal. Based on the received reference signal, the location-determination system identifies an estimated location of the receiver as follows. For each transmitter in a set of transmitters, the system computes a phase offset between the received reference signal and a replica of the transmitter's periodically-repeating component. The system also identifies an approximate location of the receiver and an approximate receive time for the received signal. The system then uses the identified approximate location and time, and the computed phase offsets, to compute pseudoranges for the set of transmitters. Finally, the system identifies the estimated location of the receiver by using the computed pseudoranges.
    Type: Grant
    Filed: June 20, 2001
    Date of Patent: February 25, 2003
    Assignee: Enuvis, Inc.
    Inventors: Andrew Chou, Benjamin Van Roy, John Tsitsiklis
  • Patent number: 6525687
    Abstract: Some embodiments of the invention provide a location-determination system that includes a number of transmitters and at least one receiver. Based on a reference signal received by the receiver, this location-determination system identifies an estimated location of the receiver within a region. In some embodiments, the system selects one or more locations within the region. For each particular selected location, the system calculates a metric value that quantifies the similarity between the received signal and the signal that the receiver could expect to receive at the particular location, in the absence or presence of interference. Based on the calculated metric value or values, the system identifies the estimated location of the receiver.
    Type: Grant
    Filed: February 12, 2001
    Date of Patent: February 25, 2003
    Assignee: Enuvis, Inc.
    Inventors: Benjamin Van Roy, John Tsitsiklis, Andrew Chou
  • Patent number: 6512479
    Abstract: Techniques are provided for aiding in acquiring a signal using the data bit information that is associated with each signal source. One aspect of the invention is to use the data bit information that is associated with each signal source when calculating the In Phase and Quadrature correlation integrals by using the sampled data associated with the received signal. By using the data bit information that is associated with each signal source, coherent correlation may be performed by breaking the signal into data blocks and performing calculations on a block-by-block basis. Coherent correlation is the calculation of In Phase and Quadrature correlation integrals for sampled data that is associated with the received signal.
    Type: Grant
    Filed: June 22, 2001
    Date of Patent: January 28, 2003
    Assignee: Enuvis, Inc.
    Inventors: Anant Sahai, Wallace Mann, Andrew Chou, Benjamin Van Roy