To provide the system and the method that distribute a clock signal with a new timing reference which is used for an existing NTSC distribution network in existence in a conventional NTSC system,

An HDTV primary reference clock generator generates a composite synchronizing signal consisting of a horizontal synchronizing signal, a vertical synchronizing signal and other signals in compliance with the NTSC system and the composite synchronizing signal is locked synchronously with a signal from an HDTV primary reference 102. An HDTV studio component 108 receives the composite synchronizing signal consisting of a horizontal synchronizing signal, a vertical synchronizing signal and other signals and uses a phase locked loop type frequency synthesizer to produce a local HDTV clock signal. The signal generated by the phase locked loop type frequency synthesizer is locked synchronously with the HDTV primary reference 102.