Patent ID: 7515670
Filing Date: 2009-04-07
Classification: H04B

Abstract:
1. A method for fine synchronization of a digital telecommunication receiver, comprising a code tracking process for maintaining fine alignment between an incoming spread spectrum signal and a locally generated code, said method comprising: storing a plurality of consecutive samples of said incoming spread spectrum signal in a delay line; determining by interpolation between consecutive samples of said incoming spread spectrum signal, by means of a first digitally controlled interpolator, an interpolated early sample anticipating an optimal sampling time instant; determining by interpolation between consecutive samples of said incoming spread spectrum signal, by means of a second digitally controlled interpolator, an interpolated middle sample corresponding to said optimal sampling time instant; determining by interpolation between consecutive samples of said incoming spread spectrum signal, by means of a third digitally controlled interpolator, an interpolated late sample delayed with respect to said optimal sampling time instant; calculating an error signal as the difference between the energy of the symbols computed from said interpolated early and late samples; and generating, from said error signal, a control signal for controlling the interpolation phase of said second digitally controlled interpolator and thereby synchronizing the incoming spread spectrum signal with the locally generated code; wherein the step of generating a control signal comprises: extracting the sign of said error signal; accumulating said sign of said error signal for the generation of an intermediate control signal; calculating the absolute value of said error signal at a time instant n; comparing said absolute value of said error signal at said time instant n with the absolute value of said error signal at a previous time instant n−1; and updating said control signal to the value of said intermediate control signal if the absolute value of said error signal at time n is smaller than the absolute value of the same error signal at time n−1, maintaining otherwise unchanged the value of said control signal.