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 containing the words system a and/or system:
“In the course of the actual attainment of selfish ends—an attainment conditioned in this way by universality—there is formed a system of complete interdependence, wherein the livelihood, happiness, and legal status of one man is interwoven with the livelihood, happiness, and rights of all. On this system, individual happiness, etc. depend, and only in this connected system are they actualized and secured.”
—Georg Wilhelm Friedrich Hegel (1770–1831)
“Society cannot share a common communication system so long as it is split into warring factions.”
—Bertolt Brecht (1898–1956)
“It is not easy to construct by mere scientific synthesis a foolproof system which will lead our children in a desired direction and avoid an undesirable one. Obviously, good can come only from a continuing interplay between that which we, as students, are gradually learning and that which we believe in, as people.”
—Erik H. Erikson (20th century)