Patent ID: 6438183
Filing Date: 2002-08-20
Classification: H04L

Abstract:
A method of tuning a digital audio broadcast receiver according to complex-valued data obtained from frequency-differential demodulation of a received phase reference symbol, comprising the steps of:(a) correlating said complex-valued data in a sliding manner, over a range or shifts, with a lower series of constant amplitude zero autocorrelation data known to have been transmitted on negatively-numbered carriers of said phase reference symbol, obtaining a lower correlation coefficient for each shift in said range; (b) correlating said complex-valued data in a sliding manner, over said range or shifts, with an upper series of constant amplitude zero autocorrelation data known to have been transmitted on positively-numbered carriers of said phase reference symbol, obtaining an upper correlation coefficient for each shift in said range; (c) finding a shift Srmax, in said range, at which said lower correlation coefficient and said upper correlation coefficient have a sum with maximum magnitude; (d) storing the lower correlation coefficient Rlomax and upper correlation coefficient Rhimax obtained at said shift Srmax; (e) determining whether said lower correlation coefficient Rlomax and said upper correlation coefficient Rhimax differ in relative magnitude by more than a first amount; (f) determining whether said lower correlation coefficient Rlomax and said upper correlation coefficient Rhimax differ in phase angle by more than a second amount; (g) deciding, from said steps (e) and (f), whether said shift Srmax is valid as a tuning indicator; and (h) adjusting the tuning of said digital audio broadcast receiver according to said shift Srmax, provided said shift Srmax is found valid in said step (g).