Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-031314-125911

Document Typedissertation
Author NameSeals, Kelly Charles
Email Address kcseals at wpi.edu
TitleEnhanced Acquisition Techniques for GPS L1C Receivers
DepartmentElectrical & Computer Engineering
  • Dr. William R. Michalson, Advisor
  • Dr. Alexander M. Wyglinski, Committee Member
  • Dr. Peter F. Swaszek, Committee Member
  • Keywords
  • GPS L1C
  • GPS Acquisition
  • GNSS
  • GPS
  • Date of Presentation/Defense2014-03-13
    Availability unrestricted


    A new, open-access Global Positioning System (GPS) signal,

    known as L1C, is the most recent of several modernized

    Global Positioning System (GPS) signals. The first launch of

    a GPS satellite with this signal is expected to occur within a

    few years. One of the interesting features of modern Global

    Navigation Satellite System (GNSS) signals, including GPS

    L1C, is the presence of data and pilot components. The

    pilot component is a carrier with a deterministic overlay

    code but no data symbols; whereas, the data component

    carries the navigation data symbols used in the receiver

    processing. A unique aspect of GPS L1C is the asymmetrical

    power split between the two components, 75% of the power

    is used for the pilot and the remaining power, or 25%, for

    the data. In addition, the pilot and the data components are

    transmitted in phase with orthogonal spreading codes.

    Unassisted acquisition of GNSS spread spectrum signals

    requires a two-dimensional search for the spreading code

    delay and Doppler frequency. For modern two-component

    GNSS signals, conventional GNSS acquisition schemes may

    be used on either component, correlating the received signal

    with either the pilot or the data spreading code. One

    obvious disadvantage of this approach is the wasting of

    power; hence, new techniques for combining, or joint

    acquisition of the pilot and the data components, have been


    In this dissertation, acquisition of GPS L1C is analyzed and

    receiver techniques are proposed for improving acquisition

    sensitivity. Optimal detectors for GPS L1C acquisition in

    additive white Gaussian noise are derived, based on various

    scenarios for a GPS receiver. Monte Carlo simulations are

    used to determine the performance of these optimal

    detectors, based on detection and false alarm probabilities.

    After investigating the optimal detectors for GPS L1C

    acquisition, various sub-optimal detectors that are more

    efficient to implement are thoroughly investigated and

    compared. Finally, schemes for joint acquisition of L1C and

    the legacy GPS C/A code signal are proposed and analyzed.

  • SealsDissertation.pdf

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