Method of signal transmission with selected signal transmission rate

A method for transmitting a signal with a signal transmission rate selected from a plurality of signal transmission rates comprising the steps of:

• predetermining a plurality of distortion allowance ranges in correspondence with the ranges of signal transmission rate;
• transmitting a distortion measurement signal from a transmitting equipment to a line;
• receiving said distortion measurement signal from said line, deciding selected values based on said received distortion measurement signal and producing a decided distortion signal;
• obtaining a difference between said received distortion measurement signal and said decided distortion signal;
• measuring the distortion amount in said obtained difference, at the line, on the basis of the variation in said transmitted distortion measurement signal received by the line;
• deciding a distortion allowance range to which said measured distortion amount belongs on the basis of the result of said measurement of the distortion amount, either at the line, or at the transmitting equipment on the basis of the measured distortion amount transmitted from the line;
• and
• starting the signal transmission with a transmission rate corresponding to the result of said decision of distortion allowance range.