Patents by Inventor Sanjai Kohli
Sanjai Kohli has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6724811Abstract: 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 an 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: GrantFiled: March 13, 2002Date of Patent: April 20, 2004Assignee: SiRF Technology, Inc.Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
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Patent number: 6633814Abstract: 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: GrantFiled: December 22, 2000Date of Patent: October 14, 2003Assignee: SiRf Technology, Inc.Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
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Publication number: 20030165186Abstract: A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the current tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.Type: ApplicationFiled: September 18, 2002Publication date: September 4, 2003Inventors: Sanjai Kohli, Charles R. Cahn
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Publication number: 20030123531Abstract: A spread spectrum receiver processes signals from a plurality of sources modulated by different spread spectrum codes by sampling the signals as received to produce an integer series of sampling segments at a sampling rate at least twice a chip rate of the codes, each sampling segment containing an integer number of bits representing a fraction of a chip of the codes, time division multiplexing each sample segment into a number of channels, correlating the bits in each sample segment in each channel in parallel with a source specific series of locally generated sequential code samples differing by one bit, summing each parallel correlation, and accumulating the summed parallel correlations for each code sample in each channel at a rate at least equal to the chip rate to derive data related to each of the sources.Type: ApplicationFiled: December 16, 2002Publication date: July 3, 2003Inventors: Sanjai Kohli, Steven Chen
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Patent number: 6574558Abstract: A terrestrial C/A code GPS receiver system derives along-track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross-track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross-track hold is alternated with clock hold to update the cross-track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.Type: GrantFiled: May 24, 2002Date of Patent: June 3, 2003Assignee: Sirf Technology, Inc.Inventor: Sanjai Kohli
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Patent number: 6522682Abstract: A spread spectrum receiver processes signals from a plurality of sources modulated by different spread spectrum codes by sampling the signals as received to produce an integer series of sampling segments at a sampling rate at least twice a chip rate of the codes, each sampling segment containing an integer number of bits representing a fraction of a chip of the codes, time division multiplexing each sample segment into a number of channels, correlating the bits in each sample segment in each channel in parallel with a source specific series of locally generated sequential code samples differing by one bit, summing each parallel correlation, and accumulating the summed parallel correlations for each code sample in each channel at at least the chip rate to derive data related to each of the sources.Type: GrantFiled: March 2, 1999Date of Patent: February 18, 2003Assignee: SiRF Technology, Inc.Inventors: Sanjai Kohli, Steven Chen
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Publication number: 20020150150Abstract: 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 an 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: ApplicationFiled: March 18, 2002Publication date: October 17, 2002Inventors: Sanjai Kohli, Steven Chen
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Patent number: 6466612Abstract: A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the currently tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.Type: GrantFiled: February 6, 2001Date of Patent: October 15, 2002Assignee: SiRF Technology, Inc.Inventors: Sanjai Kohli, Charles R. Cahn
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Publication number: 20020146065Abstract: 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 an 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: ApplicationFiled: March 13, 2002Publication date: October 10, 2002Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
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Publication number: 20020143467Abstract: A terrestrial C/A code GPS receiver system derives along-track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross-track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross-track hold is alternated with clock hold to update the cross-track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.Type: ApplicationFiled: May 24, 2002Publication date: October 3, 2002Inventor: Sanjai Kohli
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Patent number: 6421609Abstract: A terrestrial C/A code GPS receiver system derives along track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross track hold is alternated with clock hold to update the cross track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.Type: GrantFiled: July 12, 2001Date of Patent: July 16, 2002Assignee: SiRF Technology, Inc.Inventor: Sanjai Kohli
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Patent number: 6400753Abstract: 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: GrantFiled: September 5, 2000Date of Patent: June 4, 2002Assignee: SiRF Technology, Inc.Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
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Patent number: 6393046Abstract: 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: GrantFiled: April 25, 1997Date of Patent: May 21, 2002Assignee: SiRF Technology, Inc.Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
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Publication number: 20020015439Abstract: 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: ApplicationFiled: December 22, 2000Publication date: February 7, 2002Inventors: Sanjai Kohli, Steven Chen, Charles R. Cahn, Mangesh Chansarkar, Greg Turetsky
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Publication number: 20010047243Abstract: A terrestrial C/A code GPS receiver system derives along track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross track hold is alternated with clock hold to update the cross track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.Type: ApplicationFiled: July 12, 2001Publication date: November 29, 2001Inventor: Sanjai Kohli
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Patent number: 6292749Abstract: A terrestrial C/A code GPS receiver system derives along track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross track hold is alternated with clock hold to update the cross track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.Type: GrantFiled: December 8, 2000Date of Patent: September 18, 2001Assignee: SiRF Technology, Inc.Inventor: Sanjai Kohli
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Publication number: 20010009563Abstract: A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the currently tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.Type: ApplicationFiled: February 6, 2001Publication date: July 26, 2001Inventors: Sanjai Kohli, Charles R. Cahn, PhD
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Patent number: 6249542Abstract: A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the currently tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.Type: GrantFiled: March 27, 1998Date of Patent: June 19, 2001Assignee: SiRF Technology, Inc.Inventors: Sanjai Kohli, Charles R. Cahn
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Publication number: 20010002458Abstract: A terrestrial C/A code GPS receiver system derives along track position information while tracking as few as two GPS satellites by use of conventional altitude hold and a cross track hold mode in which the maximum expected deviation of the vehicle from the expected track is estimated by, for example, knowledge or prediction of the width of the roadway or other track. To maintain accuracy, cross track hold is alternated with clock hold to update the cross track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed.Type: ApplicationFiled: December 8, 2000Publication date: May 31, 2001Inventor: Sanjai Kohli
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Publication number: 20010002203Abstract: A spread spectrum receiver uses a comparison of the magnitude of the code correlation amplitudes at equal power at a one chip spacing to the magnitude at a central position there between to determine if multipath interference is present. The lead or lag error from constructive or destructive multipath interference may also be determined. Inaccuracies due to such interference may then be corrected or minimized by, for example, determining the residual code phase error and/or the prompt or accurate code phase delay.Type: ApplicationFiled: December 11, 2000Publication date: May 31, 2001Inventors: Charles R. Cahn, Mangesh Chansarkar, Sanjai Kohli