Technology

Elements of a television system
OT-1471 Belweder, Poland, 19571. power switch / volume
2. brightness
3. pitch
4. vertical synchro 5. horizontal synchro
6. contrast
7. channel tuning
8. channel switch


The elements of a simple television system are:
An image source - this may be a camera for live pick-up of images or VTR or a Film Chain-Telecine-flying spot scanner for transmission of films.
A sound source picked up by a microphone
A transmitter, which modulates one or more television signals with both picture and sound information for transmission.
A receiver (also called a tuner) which recovers and processes the picture and sound signals from the television broadcast signal.
A display device, which turns the electrical signals into visible light and images
A small amplifier and loudspeaker, which turns electrical signals into sound waves (speech, music, and other sounds) to accompany the images.

Practical television systems include equipment for selecting different image sources, mixing images from several sources at once, insertion of pre-recorded video signals, synchronizing signals from many sources, and direct image generation by computer for such purposes as station identification.

Transmission was originally over the air from land-based transmitters. The quality of reception varies greatly, and this led to the proliferation of large antennas on house roofs for best signal in the 1960s. In most cities today, cable systems deliver television over metal or optical cables, but for a fee. It can be delivered by radio from synchronous satellites, which were large for analog, and smaller dishes for digital broadcast, also for a fee, often less than cable systems, which has led to the appearance of small dishes outside of houses and apartments.

Digital systems may be inserted anywhere in the chain to provide better image transmission quality, reduction in transmission bandwidth, special effects, or security of transmission from reception by non-subscribers. A home today might have the choice of receiving analog or HDTV over the air, analog or digital cable with HDTV from a cable television company over coaxial cable, or even from the phone company over fiber optic lines. On the road, television can be received by pocket sized televisions, recorded on tape or digital media players, or played back on wireless phones over a high speed network or the internet.