Patents by Inventor Chi Shin Wang

Chi Shin Wang 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).

  • Patent number: 8466836
    Abstract: A method and device to track navigational satellite signals, are claimed. In this invention, a combination of down-sampling and frequency domain transformation are used to track the navigational satellite signals under dynamic environment. A Fast Fourier Transform (FFT) with long coherent integration has been employed to determine the varying frequency components with high resolution. By representing a number of correlation values with their average value, it is possible to represent a long sequence of input values by a smaller number of values and a relatively short length FFT can reveal the low frequency components that are present in the signal during tracking operation. A large reduction in the computational load may be achieved using this down-sampling method without compromising on the frequency resolution.
    Type: Grant
    Filed: August 31, 2005
    Date of Patent: June 18, 2013
    Assignee: CSR Technology Holdings Inc.
    Inventors: Zhike Jia, Chi-Shin Wang
  • Patent number: 8391339
    Abstract: The present invention provides systems and methods for faster acquisition and more stable tracking of spread spectrum signals with lower computational load requirements. Instead of the present day practice of using only the Prompt correlator, the systems and methods of the invention use the sum of the powers of all the correlators of a channel to determine the acquisition or tracking of the signal. These systems and methods improve the signal acquisition speed resulting in a reduced Time-To-First-Fix (TTFF). Further, these systems and methods improve the acquisition and tracking sensitivity of the receiver.
    Type: Grant
    Filed: July 5, 2006
    Date of Patent: March 5, 2013
    Assignee: CSR Technology Holdings Inc.
    Inventors: Chi-Shin Wang, Jian Cheng, Zhike Jia, Shridhara A. Kudrethaya
  • Patent number: 8094758
    Abstract: The present invention provides systems and methods for downloading navigation data to a satellite receiver under weak signal conditions. In an embodiment, the receiver uses a tracking algorithm to estimate the Doppler frequency and rate of change of the Doppler frequency to compensate the phases of the I/Q samples from the received signal to reduce the effect of the Doppler frequency. In an embodiment, differential detection based data bit decoding is provided. In another embodiment, phase compensation based data bit decoding is provided, in which the phase of samples are rotated to compensate for phase error. In an embodiment, a multiple frame strategy is provided to increase signal-to-noise ratio (SNR) and improve sensitivity, in which similar placed samples in consecutive frames are coherently summed over the consecutive frames. In an embodiment, the samples are weighted to reduce the impact of noise in the multiple frame strategy.
    Type: Grant
    Filed: December 18, 2006
    Date of Patent: January 10, 2012
    Assignee: SiRF Technology Holdings, Inc.
    Inventors: Chi-Shin Wang, Yue-Meng Chen, Zhike Jia, EnYuan Tu
  • Patent number: 7903028
    Abstract: The present invention provides systems and methods for downloading navigation data to a satellite receiver under weak signal conditions. In an embodiment, the receiver uses a tracking algorithm to estimate the Doppler frequency and rate of change of the Doppler frequency to compensate the phases of the I/Q samples from the received signal to reduce the effect of the Doppler frequency. In an embodiment, differential detection based data bit decoding is provided. In another embodiment, phase compensation based data bit decoding is provided, in which the phase of samples are rotated to compensate for phase error. In an embodiment, a multiple frame strategy is provided to increase signal-to-noise ratio (SNR) and improve sensitivity, in which similar placed samples in consecutive frames are coherently summed over the consecutive frames. In an embodiment, the samples are weighted to reduce the impact of noise in the multiple frame strategy.
    Type: Grant
    Filed: December 18, 2006
    Date of Patent: March 8, 2011
    Assignee: Sirf Technology Holdings, Inc.
    Inventors: Chi-Shin Wang, Yue-Meng Chen, Zhike Jia, EnYuan Tu
  • Publication number: 20100328145
    Abstract: The present invention provides systems and methods for downloading navigation data to a satellite receiver under weak signal conditions. In an embodiment, the receiver uses a tracking algorithm to estimate the Doppler frequency and rate of change of the Doppler frequency to compensate the phases of the I/Q samples from the received signal to reduce the effect of the Doppler frequency. In an embodiment, differential detection based data bit decoding is provided. In another embodiment, phase compensation based data bit decoding is provided, in which the phase of samples are rotated to compensate for phase error. In an embodiment, a multiple frame strategy is provided to increase signal-to-noise ratio (SNR) and improve sensitivity, in which similar placed samples in consecutive frames are coherently summed over the consecutive frames. In an embodiment, the samples are weighted to reduce the impact of noise in the multiple frame strategy.
    Type: Application
    Filed: December 18, 2006
    Publication date: December 30, 2010
    Inventors: Chi-Shin Wang, Yue-Meng Chen, Zhike Jia, EnYuan Tu
  • Patent number: 7859456
    Abstract: The present invention provides systems and methods for enabling a navigation signal receiver to perform both data assisted and non-data assisted integration to provide better integration during signal acquisition, reacquisition and tracking. In data assisted integration mode, a receiver uses known or predicted data bits to remove the modulated data bits of a received signal prior to integration. In non data assisted integration mode, when the data bits are not known or predictable, the receiver uses an optimal estimation or maximum likelihood algorithm to determine the polarities of the modulated data bits of the received signal. This may be done by determining which of various possible bit pattern yields the maximum integrated power. When the modulated data bits are not known or predictable over a limited range, the receiver carries out data assisted integration over the known or predictable data bits and additional non data assisted integration.
    Type: Grant
    Filed: October 10, 2006
    Date of Patent: December 28, 2010
    Assignee: Sirf Technology Holdings, Inc.
    Inventors: Chi-Shin Wang, Zongde Qiu, Zhike Jia
  • Patent number: 7847726
    Abstract: The present invention provides systems and methods for navigational signal tracking in low power mode to conserve the power of handheld navigation receivers. In an embodiment, the receiver cycles between sleep and wakeup states. During the sleep state, most of the components of the receiver are powered off to conserve power, and during the wakeup state, the receiver tracks navigational signals. In an embodiment, the duty cycle of the sleep/wakeup states depends on the receiver dynamic state, e.g., whether the receiver is accelerating. In another embodiment, during the wakeup state, the receiver selects a tracking mode based on the signal strength. Under weak signal conditions, a tracking mode using a long integration to track the satellite signal is disclosed. In one embodiment, a tracking mode tracks the navigation signal by performing data aided integration using known or predicted data bits, such as the TLM and HOW words.
    Type: Grant
    Filed: December 22, 2006
    Date of Patent: December 7, 2010
    Assignee: Sirf Technology Holdings, Inc.
    Inventors: Zhike Jia, Shridhara A. Kurethaya, Chi-Shin Wang
  • Patent number: 7778311
    Abstract: Methods to achieve data bit synchronization from weak navigational satellite signals are based on a maximum likelihood criterion. The bit synchronization technique may be implemented by calculating a normalized dot product of two consecutive one-millisecond correlation values. Similar normalized dot products are calculated at intervals separated by one bit duration, and these dot products are summed and compared with pre-computed thresholds to declare bit edge detection. In another implementation, the normalized dot product of adjacent correlation values is replaced by a coherent integration powers of adjacent correlation values.
    Type: Grant
    Filed: October 4, 2005
    Date of Patent: August 17, 2010
    Assignee: SIRF Technology Holdings, Inc.
    Inventors: Zhike Jia, Chi-Shin Wang
  • Patent number: 7743177
    Abstract: Provided herein is multi-function platform comprising a plurality of devices and a large memory that is external to the devices and shared among the devices. In an embodiment, a Direct Memory Access (DMA) controller is provided for each device to efficiently transfer data between the device and the shared memory. More than one DMA may be provided for a device. For example, separate DMAs may be provided for different components of a device that perform different subfunctions enabling efficient transfer of data between the different components of the device and the shared memory. In another embodiment, each device comprises a local embedded memory and is provided with a DMA for transferring data between the local memory and the shared memory. Examples of devices that can be included in the platform include a GNSS receiver, a audio player, a video player, a wireless communication device, a routing device, or the like.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: June 22, 2010
    Assignee: SIRF Technology Holdings, Inc.
    Inventors: Zhike Jia, Chi-Shin Wang, Lianxue Xiong, Hongyu Zhang
  • Patent number: 7693211
    Abstract: Fast Fourier Transform (FFT) based Phase Lock Loops (PLLs) are provided for use in navigational signal receivers. In an embodiment, a navigation receiver correlates a received navigational signal with a locally generated signal into correlation samples, e.g., one-millisecond correlation samples. The navigation receiver includes a FFT based PLL that corrects phase shifts in the correlation samples due to the Doppler frequency by considering both the Doppler frequency and its rate of change, which are obtained from a FFT computation with interpolation. The phase corrected correlation samples are then integrated over a length of a navigation data bit, e.g., 20 milliseconds, to determine the sign of the data bit of the received signal. In another embodiment, a soft decision feedback technique involving integration extending over the present data bit and several prior data bits is used to determine the sign of a present data bit of the received signal.
    Type: Grant
    Filed: April 20, 2006
    Date of Patent: April 6, 2010
    Assignee: SIRF Technology Holdings, Inc.
    Inventors: Chi-Shin Wang, Yue Meng Chen, Zhike Jia
  • Patent number: 7660373
    Abstract: A method to determine the polarity of navigation data from weak satellite signals is disclosed. After bit edge is detected, a method in frequency domain is used to determine the present bit polarity with the help of several prior data bits which are already known, is disclosed. The impact of residual frequency can be mitigated by frequency transform. This method is especially useful in removing the data modulation in the weak signal for subsequent long coherent integrations.
    Type: Grant
    Filed: October 4, 2005
    Date of Patent: February 9, 2010
    Assignee: SiRF Technology, Inc.
    Inventors: Zhike Jia, Chi-Shin Wang
  • Patent number: 7586382
    Abstract: Systems and methods are provided that compensate for frequency drift due to temperature variation without the need for a temperature sensor. In one embodiment, a navigation receiver with an integrated communication device receives a base station reference signal, which is used to periodically calibrate a local oscillator frequency. In another embodiment, the calibrated local oscillator frequency drives a counter that is used to provide code phase estimation at the start of satellite signal acquisition. To provide temperature compensation in one embodiment, the calibrated local frequency is used to drive one or more counters at different calibration rates (i.e., different time intervals between calibrations). Count values from these counters are used to determine compensation for frequency drift due to temperature variation based on predicted frequency drift variation patterns between calibrations.
    Type: Grant
    Filed: March 2, 2007
    Date of Patent: September 8, 2009
    Assignee: SiRF Technology, Inc.
    Inventors: Chi-Shin Wang, Zhike Jia, Lianxue Xiong, Yinghao Tu
  • Patent number: 7570208
    Abstract: The present invention provides GPS receivers capable of tracking very weak GPS signals particularly in an indoor environment without assistance from an external server or a network. In a preferred embodiment, a GPS receiver initially acquires and locks onto GPS satellite signals to compute receiver position outdoors. The GPS receiver then tracks at least one satellite signal indoors to maintain acquisition parameters for quick acquisition of GPS signals. To save power, the receiver automatically goes to the sleep state and periodically wakes up, i.e., powers up, to maintain the at least one satellite signal tracking. During the wakeup state, the receiver collects ephemeris data from the at least one satellite signal when the ephemeris data needs to be updated for quick acquisition of GPS signals.
    Type: Grant
    Filed: December 29, 2005
    Date of Patent: August 4, 2009
    Assignee: SiRF Technology, Inc.
    Inventors: Chi-Shin Wang, Zongde Qiu, Shridhara A. Kudrethaya, Jun Mo
  • Publication number: 20090168851
    Abstract: The present invention provides systems and methods for faster acquisition and more stable tracking of spread spectrum signals with lower computational load requirements. Instead of the present day practice of using only the Prompt correlator, the systems and methods of the invention use the sum of the powers of all the correlators of a channel to determine the acquisition or tracking of the signal. These systems and methods improve the signal acquisition speed resulting in a reduced Time-To-First-Fix (TTFF). Further, these systems and methods improve the acquisition and tracking sensitivity of the receiver.
    Type: Application
    Filed: July 5, 2006
    Publication date: July 2, 2009
    Inventors: Chi-Shin Wang, Jian Cheng, Zhike Jia, Shridhara A. Kudrethaya
  • Patent number: 7479924
    Abstract: The techniques to detect and mitigate the false reacquisition in a global satellite navigation receiver are disclosed. The false reacquisition due to frequency side-lobes and code autocorrelation secondary lobes are considered for mitigation. A set of two threshold values is used to detect correct reacquisition and reject false reacquisition. While the reacquisition of the signal is straight forward when the correlation is clear with the power above the first threshold, it is not so clear when the power is between two thresholds. So a further search for the maximum power among the retained dwells results in correct reacquisition. The search range depends upon the signal blockage interval and receiver dynamics. The feedback from navigational solution may be used to determine the search range both in frequency and code phase. In the case of frequency side-lobes, which occur only at specified frequency components, these frequencies are tested for maximum power response.
    Type: Grant
    Filed: November 14, 2005
    Date of Patent: January 20, 2009
    Assignee: SiRF Technology Holdings, Inc.
    Inventors: Zhike Jia, Shridhara A. Kudrethaya, Chi-Shin Wang
  • Patent number: 7477189
    Abstract: Provided herein are systems and methods for achieving long coherent integration in a navigational receiver to improve the sensitivity of the receiver and enable the receiver to acquire, reacquire and track signals under very weak signal conditions. In an embodiment, phase compensation is computed based on estimated Doppler frequency, rate of change of the Doppler frequency with time, and second order rate of change of the Doppler frequency. The Doppler frequency may be computed from an orbital model or ephemeris. This phase compensation is used to compensate samples of the input signal for changes in the phase due to the Doppler frequency. Frequency components of the phase-compensated samples are then computed using a frequency analysis such as a Fast Fourier Transform (FFT). The maximum frequency component is taken as an error frequency and used to compensate the samples of the input signal for residual frequency error.
    Type: Grant
    Filed: March 30, 2007
    Date of Patent: January 13, 2009
    Assignee: SiRF Technology Holdings, Inc.
    Inventors: Chi-Shin Wang, Zhike Jia, Yue-Meng Chen, Jian Cheng, EnYuan Tu
  • Publication number: 20090002227
    Abstract: Provided herein is multi-function platform comprising a plurality of devices and a large memory that is external to the devices and shared among the devices. In an embodiment, a Direct Memory Access (DMA) controller is provided for each device to efficiently transfer data between the device and the shared memory. More than one DMA may be provided for a device. For example, separate DMAs may be provided for different components of a device that perform different subfunctions enabling efficient transfer of data between the different components of the device and the shared memory. In another embodiment, each device comprises a local embedded memory and is provided with a DMA for transferring data between the local memory and the shared memory. Examples of devices that can be included in the platform include a GNSS receiver, a audio player, a video player, a wireless communication device, a routing device, or the like.
    Type: Application
    Filed: June 29, 2007
    Publication date: January 1, 2009
    Inventors: Zhike Jia, Chi-Shin Wang, Lianxue Xiong, Hongyu Zhang
  • Patent number: 7459984
    Abstract: The invention provides a method and apparatus to optimally estimate and adaptively compensate the temperature-induced frequency drift of a crystal oscillator in a navigational signal receiver. A Read-Write memory encodes two tables, one for looking up frequency drift values versus temperature readings and another one for valid data confirmation on the first table. The initially empty look-up table is gradually populated with frequency drift values while the receiver computes the frequency drift along with its position. During initial start of the receiver or re-acquisition of satellite signals, the stored frequency drift value corresponding to the current temperature is used. If no valid frequency drift value is available, the frequency drift value is computed based on the existing frequency drift values in the table. This invention reduces the Time-To-First-Fix (TTFF) of the receiver and enables the receiver to self-calibrate, thus no additional factory calibration would be necessary.
    Type: Grant
    Filed: May 26, 2005
    Date of Patent: December 2, 2008
    Assignee: Sirf Technology Holdings, Inc.
    Inventors: Chi-Shin Wang, Kudrethaya A. Shridhara, Jun Mo, Shaowei Han, Hansheng Wang
  • Patent number: 7456782
    Abstract: The present invention provides GPS receivers with clock calibration for fast reacquisition of GPS signals after waking up from a sleep state or coming out of signal blockage. In a preferred embodiment, a GPS receiver comprises a local clock based on an oscillator, e.g., crystal oscillator. The GPS receiver calculates a clock calibration value based on a computed oscillator count for the period during which the GPS receiver is in the sleep state or the signal is blocked. This clock calibration value is used to calibrate the local clock after the GPS receiver wakes up or comes out of signal blockage for fast reacquisition of GPS signals.
    Type: Grant
    Filed: December 29, 2005
    Date of Patent: November 25, 2008
    Assignee: SiRF Technology, Inc.
    Inventors: Chi-Shin Wang, Lianxue Xiong, Zhike Jia, Lei Dong, Jingbin Liu
  • Patent number: 7439907
    Abstract: The present invention provides methods and systems that enable a mobile navigation receiver to accurately determine its trajectory with non-current ephemeris in stand-alone mode. In an embodiment, the receiver computes the position for the same location using non-current ephemeris and current ephemeris at different time instances. The receiver then determines a position correction by finding the difference between these two computed positions, and applies this correction to the trajectory generated with non-current ephemeris to obtain a more accurate trajectory. In another embodiment, the receiver computes an initial position of the receiver using non-current ephemeris and finds the difference between the computed initial position and an accurate approximation of the initial position. The receiver then shifts the subsequent receiver trajectory computed using non-current ephemeris by the difference to obtain a more accurate trajectory.
    Type: Grant
    Filed: November 20, 2006
    Date of Patent: October 21, 2008
    Assignee: SIRF Technology Holdihgs, Inc.
    Inventors: Chi-Shin Wang, David Wang, Wentao Zhang, Jun Mo, Lei Dong