Patent ID: 6922436

Claim:
A method for fast clock timing recovery of transmitted data between a master χDSL modem and a slave χDSL modem wherein said data is submitted over an χDSL transmission medium comprising the step of: (a) providing the master χDSL modem, synchronized by its own timing clock, for data transmission, (b) providing the slave χDSL modem, synchronized by its own timing clock, for data reception, (c) providing the χDSL transmission medium connecting the master χDSL and the slave χDSL modems, (d) encoding and transmitting the data at the master χDSL modem as said sequence of symbols using pre-determined QAM states, a sequence having a frequency, (e) receiving the data at the slave χDSL modem as said sequence of symbols, (f) sampling the received data at a symbol rate and converting the sampled data into digital form, (g) splitting the digitally converted data into in-phase (I) and quadrature (Q) channels, (h) low-pass filtering of the digitally converted data corresponding to the in-phase and quadrature channels, (i1) re-sampling the filtered data at a re-sampling rate which is at least twice the symbol rate, (i2) modulating each of said re-sampled data with the two discrete-time sequences: cos(0.5 πn)=. . . , 1, 0, −1, 0, . . . sin(0.5 πn)=. . . , 0, 1, 0, −1, . . . (i3) computing a normalized spectral line vector corresponding to the re-sampled modulated data, (i4) tuning the symbol rate in dependence of the imaginary part of the normalized spectral line vector for tracking the frequency of the sequence of symbols.