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NY SMPTE Meeting



Last night, one of the most interesting local SMPTE meetings in recent
memory was held at the CBS Broadcast Center on W. 57th Street in New York.
The subject of the meeting was a progress report on digital television.

The first past of the night was spent discussing how CBS broadcasts digital
programming on-air in New York City, and relays it to their affiliates.
They've added new equipment and facilities to their existing systems in a
sensible, cost-concious manner, essentially duplicating the master control
and program origination portions of the Broadcast Center in HD, complete
with ties back to the NTSC sections.  It obviously represents a great deal
of hard work and expense--particularly in constructing a brand-new UHF
transmitter facility on the 83rd floor of the Empire State Building--but
they got the job done.  CBS also described their field test methods, which
were quite extensive.

Two forms of programming received off-air from WCBS-DT were shown on
CRT-based monitors and a Sony large-screen video projector.  (This projector
appeared to be a three-tube CRT type.)  The first program was the regular
CBS NTSC network feed, upconverted to HDTV, which is what they air at times
when there is no HD programming scheduled.  This was interrupted live for a
re-broadcast of the October 30 launch of the space shuttle, which was done
specially for the presentation.   We then saw some HDTV programming
originated from a local HD-D5 tape.  Subjectively, there was little
noticeable difference in quality compared to the off-air signal.  (Some
motion artifacts created when the shuttle video was originally compressed in
Florida were visible, however.)  The images were extremely sharp and
reasonably bright, but even in HD, video is still video.  The colors from
the projector were saturated and tilted a bit towards red, but this might
only have been the set-up of that unit.

Problems brought up by the audience in the Q&A session that followed were
not glossed over.  There have been some audio delay issues found between
particular ATSC encoders and various receivers.  (None were observed in the
demonstration.)  More testing and refinement is needed among manufacturers
to make sure that every receiver works properly with any encoder.  CBS'
research labs are directly across the street from the Broadcast Center, and
they have been working with manufacturers to test both ends of the system.
While the field tests proved that the computer modelling of DTV broadcast
propagation used by the FCC and the industry is highly accurate, at present
power levels there are still areas--including the "concrete canyons" of the
city--where off-air DTV reception will be problematic.  These are generally
places where NTSC broadcast reception doesn't work either, which means that
cable system issues still have to be worked out before everybody will be
able to get the signal.  The multipath problems that were predicted for
ATSC-DTV have been observed in some places, but new receiver chipsets on the
way will hopefully address this.  Interference both to and from existing
NTSC services is still a concern, and nobody really knows what is going to
happen when two or more DTV stations begin broadcasting at full power in the
same area on adjacent channels.  But one got the feeling that regardless of
the problems, there is every confidence in the system; there's nothing about
it that can't be fixed.

The evening was topped off by a tour of the WCBS-DT master control room.
CBS has done an excellent job of groundbreaking with hard work, good
engineering, and money.  And their presentation was top-notch.
DTV is here, it seems to work fine, and it can only get better.

Christopher Bacon



---
Thanks to Allan Taylor of Sony Broadcast Europe for support in 1999
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