FIGnition FUZE Hardware Reference Manual page 14

In operation TV stations convert the series of dots into radio waves and a TV converts
them back into a stream of dots. Composite video doesn't need to convert the stream of
dots. Instead, they are sent directly along a cable from the source (e.g. FIGnition) to the
TV. For PAL TV, every frame consists of 312.5 scan lines and every scan line is 64µs long
of which no more than 51.2µs can be used for dots.
In addition to the image itself, the signal needs to send information about when to start a
new frame and when to start a new scan. These are called Frame Sync and Horizontal
Synchronization signals [Fig 3.3].
All this is controlled by a single signal at different voltages. A voltage between 0.3v and
1.0v is used to send a dot (0.3v is black and 1.0v is white); a voltage of 0v is a synchroni-
zation signal: a Horizontal sync is 0v held for 4.3µs and a Vertical sync is a special pattern
of 0v and 0.3v signals over a 480µs period [Fig 3.4].
Scan period = 64µs
Visible period = 51.2µs
Fig 3.2
HSync: 4.3µs
Fig 3.3
625/2
scans
Frame
Sync