Abstract: An apparatus in a video signal transmission system for measuring cable length and compensating for cable loss is described. A number of pilot signals of different frequencies are compressed into one of the three color signals during the vertical sync periods in a time-division manner. The vertical and horizontal sync signals are compressed into the other two color signals. The video signal is transmitted over a cable having at least three pairs of wires, each color signal being transmitted by one pair of wires. A pilot signal converting circuit obtains the levels of the pilot signals transmitted by the cable. A compensation control circuit averages the levels of the multiple pilot signals of different frequencies over a number of vertical sync periods, and generates compensation control signals based on the average level of the pilot signals. The compensation control signals are used to perform video signal compensation.

Abstract: An apparatus in a video signal transmission system for measuring cable length and compensating for cable loss is described. A number of pilot signals of different frequencies are compressed into one of the three color signals during the vertical sync periods in a time-division manner. The vertical and horizontal sync signals are compressed into the other two color signals. The video signal is transmitted over a cable having at least three pairs of wires, each color signal being transmitted by one pair of wires. A pilot signal converting circuit obtains the levels of the pilot signals transmitted by the cable. A compensation control circuit averages the levels of the multiple pilot signals of different frequencies over a number of vertical sync periods, and generates compensation control signals based on the average level of the pilot signals. The compensation control signals are used to perform video signal compensation.