Video Stabilising Amplifier (4U BMM)
This unit is being designed as a general purpose stabilising or
"processing" amplifier for use on the output of equipment such as vision
mixer, video tape recorders and standards converters. It includes all
the functions necessary to ensure that the signal at its output will
always be contained within the amplitude limits of PAL System I. The
organisation is modular and such that facilities can be built 'up, as
required, from a group of optional printed circuit cards. Design work
started in the Spring of this year and will continue until March 1978.
A pre-production batch will be manufactured in early 1978 to permit the
re-equipping of the Television News vision mixers with the design.
PAL Coding
New BMM Coder: This job was originally started to convert, in the
simplest possible manner, the existing imperial design onto the new BMM
chassis system. However, discussions with Studio Capital Projects
Department and the users quickly established that it should be
significantly updated and take account of future requirements. Among
the new facilities provided will be an integral colour bar generator,
full waveform blanking, and a low pass filter to limit the output
bandwidth to 6MHz. In December of this year the specification was
agreed, and detailed design work will start in January of 1978.
Comb Filters for PAL Coders: For many years BBC engineers have been
trying to find an effective, yet economic, method of reducing the mutual
cross talk that occures in PAL decoders between the chrominance and high
frequency luminance components of the received signal. One of such
defects, commonly known as "Cross Colour", has been partly allieviated
by the introduction of notch filters into the 1 uminance channel of the
coder (see last years report). This year Special Studies Section have
developed an alternative approach employing comb filters and PAL
modification. Experimantal equipment is being constructed with a view
of performing subjective tests in conjunction with Research Department
in early 1978.
New Colour Synthesiser for Studio use (4U BMM)
This equipment enables coloured captions to be generated from a
monochrome source for insertion via a vision mixer into programme
output. Like the new PAL coder the design will incorporate the latest
facilities requested by the users. Features not available on the older
unit include the ability to work with three different colours and tint,
in a linear manner, monochrome film or video tape inserts. The
specification was agreed in November of this year and design work will
continue into the summer of 1978.
Matrix Remote Control Equipment
This unit enables one destination of a video switching matrix to be
controlled from a remote point. The design will be completed in the
Spring of 1978 and Designs and Equipment Department will be co-operating
in the early manufacture of some 25 systems for Type 5 Colour Mobile
Control Rooms.
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