Design an Adjustable Narrow Correlator to Track GPS Signals

Multipath signals problem is still the main challenge for the global positioning system (GPS) receiver to obtain an accurate localization measurement. However, many techniques have been developed to mitigate the impact of these undesired signals at the expense of adding a burden to the GPS receiver design. Even though, none of the techniques in the works of literature was able to solve the loose signal lock issue efficiently. In this piece of work, we used a new approach to maintain the tracking synchronization when the receiver moves from outdoors to indoors /harsh environment. We design a dynamic narrow correlator in the delay lock loop, which made the space between the early and late correlators adjusted according to the receiver’s location. Consequently, this will enable the receiver to keep tracking the received GPS signal in a challenging environment and reduce the thrashing the available resources (power/processing) to acquire the GPS signal again. The results show that the ranging error has been reduced in comparison with a traditional narrow correlator, as well as the bit transition in the in-phase arm has been also maintained.

Complex Dynamics of the Fractional-Order Rössler System and Its Tracking Synchronization Control

Numerical analysis of fractional-order chaotic systems is a hot topic of recent years. The fractional-order Rössler system is solved by a fast discrete iteration which is obtained from the Adomian decomposition method (ADM) and it is implemented on the DSP board. Complex dynamics of the fractional-order chaotic system are analyzed by means of Lyapunov exponent spectra, bifurcation diagrams, and phase diagrams. It shows that the system has rich dynamics with system parameters and the derivative order q. Moreover, tracking synchronization controllers are theoretically designed and numerically investigated. The system can track different signals including chaotic signals from the fractional-order master system and constant signals. It lays a foundation for the application of the fractional-order Rössler system.