Abstract: An apparatus for synchronizing a terminal equipment such as a TV camera includes an external synchronizing signal generator which includes a switching circuit which generates two frequency signals and alternately transmits these signals to the terminal equipment which is provided with a decoder circuit decoding an alternating rate of the two signals outputted from the synchronizing signal generator, and an internal synchronizing signal generating circuit receiving a decoder circuit and generating a new synchronizing signal on the basis of the decoded signal.

Abstract: In a method and apparatus for converting a synchronizing signal received from a controller for controlling a TV camera into a new synchronizing signal, a single frame synchronizing pulse for every two field pulses is generated on the basis of at least a vertical drive signal of the synchronizing signal received from the controller. The new synchronizing pulse which has a level higher than the white level and lower than the black level of a composite video signal generated by the TV camera is injected into a video transmission line connected to the TV camera for synchronizing the latter on the basis of the injected synchronizing pulse.

Abstract: In a method and apparatus for converting a synchronizing signal received from a controller for controlling a TV camera into a new synchronizing signal, a single frame synchronizing pulse for every two field pulses is generated on the basis of at least a vertical drive signal of the synchronizing signal received from the controller. The new synchronizing pulse which has a level higher than the white level and lower than the black level of a composite video signal generated by the TV camera is injected into a video transmission line connected to the TV camera for synchronizing the latter on the basis of the injected synchronizing pulse.

Abstract: In an information transmission system including transmitters, a receiver, and a transmission line for transmitting information signals from the transmitters to the receiver, the transmission line is shared by the information signals and external sync signals which are adapted to synchronize the transmitters to each other. The external sync signals have a voltage level higher than a maximum voltage level of the information signals or lower than a minimum voltage level of the same, and are transmitted to the transmitters over the transmission line by using blanking level portions of the information signals. The external sync signals are separated from the information signals based on their level difference and, then, applied to the transmitters.