Eagle-eyed viewers could see the identification letters change on the corner of the screen. Those with poor vertical hold would have to wait a little longer for the picture to stabilise. Occasionally, a transmitter would be switched out of sequence and the viewers would be treated to the sight of 100 kW of video feedback. With the establishment of the Warkworth satellite station in 1971, New Zealand could finally communicate with the rest of the world. The first live broadcast received by satellite was the 1971 Melbourne Cup on 2 November. For the first 13 years, NZBC TV broadcast solely in black and white. Colour television, using the Phase alternating line (PAL) system, was introduced on 31 October 1973, in preparation for the 1974 British Commonwealth Games, held in Christchurch the following February. Due to the lack of colour facilities, only four of the ten sports (swimming, diving, athletics and boxing) could be broadcast in colour. The introduction of a second TV channel in 1975 also saw the reorganisation of broadcasting in New Zealand. On 1 April 1975, the NZBC was split into 3 separate state owned corporations: Television One, Television Two and Radio New Zealand. The existing NZBC television service became TV One, and was based in Avalon Television Centre in Lower Hutt which opened that day. TV One used the WNTV1 and DNTV2 studios and the existing channel frequencies, while AKTV2's Shortland Street studios and CHTV3 studios and new channel frequencies were used for the new TV2, which commenced later that year. In 1980, TV One and South Pacific (known once again as TV2) were merged into a single organisation, Television New Zealand (TVNZ).