405-line Television System - System A

System A

405-line is System A in the CCIR assignment of broadcast systems. The audio uses Amplitude Modulation rather than the Frequency Modulation in use on modern analogue systems. In addition, the system was broadcast in an aspect ratio of 5:4 until 3 April 1950 when it changed to the more common 4:3 format.

All System A transmitters used vestigial sideband transmission, with the single exception of Alexandra Palace in London, which closed down in 1957 when it was replaced by Crystal Palace.

System Lines Frame rate Channel bandwidth (in MHz) Visual bandwidth (in MHz) Sound offset Vestigial sideband Vision mod. Sound mod Aspect ratio Effective resolution (4:3).
System A 405 25 5 3 -3.5 0.75 Pos. AM 4:3 (5:4 before 1950) 503 x 377 (theoretical)

Read more about this topic:  405-line Television System

Famous quotes related to system a:

    The golden mean in ethics, as in physics, is the centre of the system and that about which all revolve, and though to a distant and plodding planet it be an uttermost extreme, yet one day, when that planet’s year is completed, it will be found to be central.
    Henry David Thoreau (1817–1862)