Patent Document ID: 4679208
Application ID: 06760116
Patent Flag: 1

Claim One:
1. A tuning device for an equalization system in which a known training pattern is transmitted to facilitate equalization of subsequently transmitted data whenever said data is to be transmitted, comprising: equalizer means for equalizing a signal received over a signal transmission channel with respect to a characteristic of said signal transmission channel; first multiplier means supplied with the received signal which has been equalized by said equalizer means; signal decision means for discriminating a phase of an output signal of said first multiplier means in relation to the phase of a reference signal; subtractor means for providing a difference, or error, between the output signal of the first multiplier means and an output signal of the signal decision means which is representative of a discriminated phase, and producing an error signal; second multiplier means supplied with the error signal from said subtractor means for supplying an output signal of said second multiplier means to the equalizer means; carrier phase compensation means supplied with the error signal from the subtractor means for applying an output of said carrier phase compensation means to the first and second multiplier means; insensitive area decision means supplied with the output signal of the first multiplier means for, when the output signal of the first multiplier means lies in a sensitive area defined as a predetermined region of a phase plane in which convergence of equalizer coefficients to desired values is relatively likely to occur, causing the error signal from the subtractor means to be applied to said carrier phase compensation means and the second multiplier means and, when the output signal of the first multiplier means lies in an insensitive area defined as regions of the phase plane outside of the sensitive area where convergence of equalizer coefficients to the desired values is less likely to occur than in the sensitive area, interrupting the supply of the error signal from the subtractor means to the carrier phase compensation means and the second multiplier means thereby disabling operation of the carrier phase compensation means and the second multiplier means, said insensitive area decision means comprising means for producing decision lines which define boundaries of said sensitive and insensitive areas; and means for varying said decision lines during reception of said training pattern so that the sensitive area is increased.