The amplified video signals are amplitude modulated using a suitable r.f. carrier wave in a transmitter called ‘AM' picture transmitter. Similarly, the amplified audio signals are frequency modulated using another r.f. carrier wave of higher frequency in a transmitter called ‘FM' sound transmitter.
These video and audio modulated carrier waves together are fed to the transmitting antenna on a tower. The transmitting antenna broadcasts the combined signal radiation into space.