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 word system:
“Psychoanalysis is an attempt to examine a person’s self-justifications. Hence it can be undertaken only with the patient’s cooperation and can succeed only when the patient has something to gain by abandoning or modifying his system of self-justification.”
—Thomas Szasz (b. 1920)
“How natural that the errors of the ancient should be handed down and, mixing with the principles and system which Christ taught, give to us an adulterated Christianity.”
—Olympia Brown (1835–1900)