| 摘要 |
In a synchronous data transmission system wherein data transmission is achieved by modulating a carrier wave of frequency fc at the signaling rate 1/T, a method for determining the initial phase value by which the phase of the receiver clock is to be varied during an initial synchronization operation during which a synchronization signal, the spectrum of which includes two distinct lines at frequencies f1=fc-1/2T and f2=fc+1/2T, is transmitted comprising the steps of: (a) sampling the synchronization signal fed into the receiver at the rate 1/ tau which is a multiple of the signaling rate, to provide a signal x(k tau ) where k=a, 1, . . . , (b) multiplying the signal X( tau ) by itself to provide a signal s(k tau ). (c) computing the coefficient Co, which corresponds to the frequency 1/T, of the discrete Fourier transform of signal s(k tau ) from N samples thereof, the number N being determined from the resolution R=1/N tau required to overcome the effects of the frequency components, other than the component at frequency 1/T, of signal s(k tau ), and (d) computing the phase of coefficient Co that represents the initial phase value by which the phase of the receiver clock is to be varied. |
