Abstract: A method and communications device for controlling the line rate used on a communications link. The method includes receiving frames of digital information, computing a measure of the number of frames received in error in a sliding time window and generating a command to change the line rate as a function of the measure. The use of a sliding time window captures variations in the line quality over an extended period of time; thus, significant disturbances which might otherwise be missed are captured. The measure of the number of frames received in error is computed by applying a many-to-one mapping to the actual number of frame errors received since a previous sampling instant; thus, insignificant short-term disturbances which might otherwise temporarily corrupt the line quality estimate are eliminated.