Abstract: A transmission system in which wide band electrical signals are transmitted along a transmission line has repeater stations located at intervals along the line for boosting and equalizing the signals. Each repeater station has an equalizer having a frequency response characteristic which generally complements that of the section of the transmission line which it covers. The frequency response characteristic of the equalizer is capable of adjustment to match the section of transmission line which feeds it. The adjustment required will vary when the section of transmission line feeding it has a length differing from that of a norm and where the line is subject to temperature changes. The repeater station incorporates a feedback chain which senses a pilot transmitted along the section of transmission line and responds to the monitored level of the pilot signal to automatically adjust the characteristic of the equalizer until it matches that of the transmission line section in question.