| 摘要 |
An apparatus and method for a data communications device such as a modem (100, 101) to determine carrier frequency offset and timing frequency offset, from a received probe signal. The various embodiments utilizing a processor (108) or digital signal processor (106) receive first and second sets of a transmitted probe signal having known characteristics, and determine a set of phase differences for the tones comprising the probe signal (702, 703, 704, 705). The various method and apparatus embodiments then form a linear approximation from the set of phase differences to determine the carrier frequency offset and the timing frequency offset (706). In the preferred embodiments, the linear approximation is formed from a minimization of a least square error estimate proportionally weighted by either signal to noise ratios or normalized, average amplitudes of the set of tones of the received probe signal.
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