By Ralph A. Haller, Federal Communications Commission
The Advisory Committee on Cable Signal Leakage developed the Cumulative Leakage Index (CLI) in an attempt to provide a simple, positive means to assure that cable television systems do not interfere with aircraft navigation or communications systems. The CLI represents the best combined efforts of the cable industry, the aviation industry, the Federal Aviation Administration (FAA), and the Federal Communications Commission (FCC) to develop a measurement technique that, when fully employed, will allow extreme freedom for the cable operators to use any desired carrier frequencies on their cables.
For a well-maintained, leak-free cable system, the CLI requires little effort to accomplish. Measurements may be made either on the ground or in the air. Once the CLI has been analyzed and found to be in compliance, the cable operator has a high degree of assurance that no interference will be caused in the airspace.