The use of TV signals as a frequency reference for synchronous transmitters

By using some external reference frequency which is common to all transmitters in a broadcasting network, it is possible to lock the transmitter source and achieve high stability synchronous working. One useful source of such an external reference is the line frequency of a national TV service. The use of such a technique avoids the need for high precision oscillators with measuring equipment and adjustment procedures at each transmitter site. This technique is equally applicable to networks transmitting in the MW, SW and VHF bands