By William T. Homiller, General Instrument Jerrold Division
The rate of increase in distribution system bandwidth and signal loading has exceeded the rate at which amplifier noise and distortion performance has been improved. This has resulted in some dependence upon headend based techniques, such as harmonically related coherent picture carriers. The continuation of this trend demands additional techniques to supplement the development of improved amplifier technology.
A headend system capable of coherent carrier, sync suppression and synchronized video operation was constructed. The hardware implementation of each method is described. A representative distribution cascade was used to determine the effect of each headend technique on system distortion performance. Both subjective and measurable effects were investigated, with the various techniques were evaluated individually and in combination.