Added note from http://www.tvhistory.btinternet.co.uk/html/body_telstar_tx.html
Because of the problems they had experienced, engineers at Goonhilly
asked America for a second test broadcast, in order to correct the
tracking of the receiving aerial. This was arranged for the early hours of
July 12th, and, happily, was more successful this time round. The
transmission consisted of a number of test cards and a short talk about
satellite communications by the AT&T chairman. For the first time,
sound was also carried, though the quality was very poor unfortunately.
First Satellite Colour
On 16th July 1962, experimental colour transmissions from Britain were
picked up in Maine, US, therefore becoming the first transatlantic colour
satellite relay. Although designed as a test loop to and from Goonhilly
Downs via Telstar, the signals were fairly easily recoverable in America,
even when the satellite was at its 3500 mile extreme distance. There was
some interference on vision, becoming less noticeable as Telstar
swung closer to Earth on its elliptical orbit.
During the transmission, a caption explained that the signal was coming
from the British Post Office via Telstar. There were also colour test
patterns and pictures of the control rooms inside the satellite station.
This was the first of half a dozen colour transmissions by Telstar I.
Later in 1962 closed-circuit colour medical pictures were sent from
Britain to a doctorsí conference in Washington.