Wales, and the resulting performance at Llandrindod Wells (the end of
the chain) has been recorded in London twice daily over the telephone,
using an automatic monitor together with a specially modified automatic
fault reporter. These tests suggested some minor modifications to the
proposed limits, and with these changes the revisions are now being
implemented. The fault reporter adaptation has shown itself to be very
useful, and a properly designed unit has now been developed.
Video Amplifiers and Equalisers
A new series of video amplifiers and equalisers has been designed on the
BMM metric chassis system. These
include
an
improved
high
level
sender and a l5dB gain low-noise
amplifier with associated
equalisers.
Other video
equalisers
which have been designed include a
variable one for Outside Broadcasts
which is intended to cope with
distortions commonly experienced
with long cables, and a trimming
equaliser which can deal with small
variations in signal parameters.
The final meetings in the period
1974 to 1978 of the CCIR Study Group
took place this year. The draft
Recommendation which deals with
international television
transmission was completed, largely
due to the efforts of the BBC's
represen~ation at the meeting.
Other aspects which were covered included a new Recommendation
Sound-In-Syncs,
and
a
revision of the Recommendation
concerning
measurement of audio-frequency noise.
International Activities
Video Equaliser
for
the
PROJECTS COMPLETED
l3-Channel PCM System on 6336kbit/s
A new coder monitoring unit has been provided for London Control Room.
This, with its associated control panel, enables aural monitoring of
selected channels from the bit-stream to be carried out, in either mono
or stereo as required. Also new indication facilities concerning the
routing and status of the system have been designed and built.
Synchronous Regenerator for Ceefax
An improved synchronous regenerator has been designed and a prototype
has been built and tested. Ceefax field trials have indicated a likely
need for large numbers of these units to ensure that the service area
for Ceefax is not very different from that of television.
Redesign_of Audio_Fr~quency Units on New Chassis
Variou8 audio-frequency units, including an
and voice frequency ringing generators
equaliser for Local Radio,
and detectors, have been
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