Broadcast television systems

Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals.

For the company, see Broadcast Television Systems Inc.

Analog television systems were standardized by the International Telecommunication Union (ITU) in 1961,^[1] with each system designated by a letter (A-N) in combination with the color standard used (NTSC, PAL or SECAM) - for example PAL-B, NTSC-M, etc.). These analog systems for TV broadcasting dominated until the 2000s.

With the introduction of digital terrestrial television (DTT), they were replaced by four main systems in use around the world: ATSC, DVB, ISDB and DTMB.

– 405-line system

A

– 625-line system

B

– Belgian 625-line system

C

– I.B.T.O. 625-line system

D

– French 819-line system

E

– Belgian 819-line system

F

2 × 3 × 3 × 5 gives (non interlaced)

90 lines

2 × 2 × 2 × 2 × 2 × 3 gives (non interlaced)

96 lines

2 × 2 × 3 × 3 × 5 gives (non interlaced) (used in Germany in mid-1930s before switch to 441-line system)

180 lines

2 × 2 × 2 × 2 × 3 × 5 gives (used for the experimental Baird transmissions in Britain [See Note 1])

240 lines

3 × 3 × 3 × 3 × 3 gives

243 lines

7 × 7 × 7 gives (early North American system also used in Poland and in Soviet Union before WW2)

343 lines

3 × 5 × 5 × 5 gives

375 lines

3 × 3 × 3 × 3 × 5 gives System A (used in Britain, Ireland and Hong Kong before 1985)

405 lines

2 × 2 × 2 × 5 × 11 gives (non interlaced)

440 lines

3 × 3 × 7 × 7 gives (used by RCA in North America before the 525-lines NTSC standard was adopted and widely used before WW2 in Continental Europe with different frame rates)

441 lines

2 × 3 × 3 × 5 × 5 gives (non interlaced)

450 lines

5 × 7 × 13 gives (used in France before WW2)

455 lines

3 × 5 × 5 × 7 gives System M (480i) (a compromise between the RCA and Philco systems. Still used today in most of the Americas and parts of Asia)

525 lines

3 × 3 × 3 × 3 × 7 gives (Developed by Philips used for a while in the late 1940s in the Netherlands)

567 lines

5 × 11 × 11 gives (proposed by Philco in North America before the 525 standard was adopted)

605 lines

5 × 5 × 5 × 5 gives (576i) (designed by Soviet^[10]^[11]^[12]^[13]^[14] engineers during the mid-late 1940s, introduced to Western Europe by German engineers.)

625 lines

2 × 3 × 5 × 5 × 5 gives at 50 frames (used for 720p50 [See Note 2])

750 lines

2 × 3 × 5 × 5 × 5 gives 750 lines at 60 frames (used for [See Note 2])

720p60

3 × 3 × 7 × 13 gives (737i) (used in France in the 1950s)

819 lines

3 × 7 × 7 × 7 gives (proposed but never adopted around 1948 in France)

1,029 lines

3 × 3 × 5 × 5 x 5 gives at 25 frames (used for 1080i50 but not 1080p25 [See Note 2])

1,125 lines

3 × 3 × 5 × 5 x 5 gives 1,125 lines at 30 frames (used for but not 1080p30 [See Note 2])

1080i60

As interlaced systems require accurate positioning of scanning lines, it is important to make sure that the horizontal and vertical timebase are in a precise ratio. This is accomplished by passing the one through a series of electronic divider circuits to produce the other. Each division is by a prime number.

Therefore, there has to be a straightforward mathematical relationship between the line and field frequencies, the latter being derived by dividing down from the former. Technology constraints of the 1930s meant that this division process could only be done using small integers, preferably no greater than 7, for good stability. The number of lines was odd because of 2:1 interlace. The 405 line system used a vertical frequency of 50 Hz (Standard AC mains supply frequency in Britain) and a horizontal one of 10,125 Hz (50 × 405 ÷ 2)

Television antenna

Transmission technology standards

Defunct analog systems

Analog television systems

Analog television system audio

Digital television systems

History

Characteristics of television systems. , ITU-R Recommendation BT.470-2. [1]

International Telecommunication Union

FARWAY IRFC, TV and Radio Transmission, Radio Data System Encoders, Broadcasting Technologies

by Alan Pemberton

World Analog Television Standards and Waveforms

by Paul Schlyter

Analog TV Broadcast Systems

a scan from a 1932 French magazine