A Harmonically Related Carrier System for Cable Television

A system of harmonically related visual carriers has many advantages for transmission in broad-band cable systems. All intermodulation products fall "zero-beat" with desired carriers and their visible effect is therefore drastically reduced. Prudent control of the relative phase of these harmonic carriers allows reduction in the peak-to-peak amplitude of the superposed carriers with consequent reduction of distortion in the system amplifiers. The system has been used for more than a year to provide 14 000 subscribers with 21 channels of television service.