CCIR System I

[2] As of late 2012, analogue television is no longer transmitted in either the UK or the Republic of Ireland.

South Africa is still broadcasting in System I, but have plans to end the service at any time.

The total RF bandwidth of System I (as originally designed with its single FM audio subcarrier) was about 7.4 MHz, allowing System I signals to be transmitted in 8.0 MHz wide channels with an ample 600 kHz guard zone between channels.

(This behaviour would cause some U/V crosstalk in the NTSC system, but delay-line PAL hides such artefacts.)

Starting in the late 1980s and early 1990s it became possible to add a digital signal carrying NICAM sound.

Good channel planning means that under normal situations no ill effects are seen or heard.

A written answer[7] in the Dáil Éireann (Irish parliament) shows that even by mid-1988 Ireland was transmitting on UHF from only four main transmitters and 11 relays.† Channels 35 to 37, between UHF Band IV and Band V, were originally reserved for radio astronomy.