Television systems

Televisions across the world use slightly different systems. This is partly historical, partly political. NTSC, PAL and SECAM are the three main systems you’ll hear about, although each have local variations.

America introduced colour television (NTSC) in the 1950s, a 525-iine 30-frames per second system. The rest of the world watched and made a few modifications before introducing their own systems. SECAM, a 625-line system started in France in the late 1960s, about the same time that PAL was developed.

One of the main defining criteria of a national television system is the local electricity supply. American electricity has 60 cycles per second (Hz), so it was logical for them to use 60 fields/30 frames per second. The British, on the other hand, have only 50 Hz, so they use 50 fields per second for their PAL system.

Converters

For directors it means that tapes and live satellite feeds from other parts of the world cannot be put straight to air. Signals can be put through black boxes that convert them from one system to another, although there is a quality loss, and a slight delay to the signal.

The reason for the quality loss is that converters have to calculate how the picture should look between particular lines and frames.

Conversion generations

Where this loss becomes critical is when a signal has passed through more than one converter, which happens more often than we care to admit. It has become prevalent as television companies across the world exchange pictures on a daily basis (news and sport getting bounced around the world the most).

Widescreen

Many people would like us to switch to a widescreen format – the most common being 16:9 (from the current 4:3). This suits drama and films but has little benefit for talking-heads shows. The cost of replacing all television production equipment and receivers would boost the sales bonuses of some companies more than a tiny bit.

HDTV

High definition television has been developing for years without getting universal acceptance. Typically (I say typically because there are a number of different systems) there are just over a thousand lines on the screen, instead of 625 for Pal or 525 for NTSC. This is also a widescreen format.

Widescreen format