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Tech Note - 041
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Subj: DTV Construction
(Ed note: Roy Trumbull,
Asst. Chief Engineer at KRON in San Francisco.
transmission line run for a DTV installation makes use of tuned
line and elbows so that the entire run can be kept as flat as possible.
Digital television requires it.
came as a surprise is that special precautions must be taken on
the shorter runs within the transmitter room such as the lines from
transmitters to a combiner or from a transmitter to a mask filter.
The reason is that an IOT requires a hard 50 ohms established at
its output. That can be done several ways. The first is to have
a fine matcher in the horizontal section after the first elbow or
installed as a stand-alone section a wavelength or more after the
first elbow. Elbows present a discontinuity. The second way is to
“slug” the line by putting collars on the inner conductor at the
beginning and end of the run. In either case a network analyzer
is required. Installing slugs requires the expertise of someone
who has done it before.
you don’t match the line coming out of the transmitter, the famous
DTV peaks will get you and start cooking the line. You will also
experience frequent shutdowns and crowbars and may even pop your
beam supply breaker.
question, that I lack an answer to, is how to pick the sample point
used for generating the linear and non-linear correction files.
One school of thought says that the non-linear correction, that
compensates for transmitter distortions, should use a test point
just after the transmitter and before the mask filter. The other
opinion is that the non-linear correction should be done using the
same point used for linear correction. That would be a point after
the mask filter.
a transmission line sample can be a problematic. RF from other stations
will be present and may overload the Vector Signal Analyzer. Perhaps
a special filter is needed to take out unwanted stations without
introducing significant group delay to your own channel.
do you know that the test point is really a good proxy for the transmitted
signal? That’s the heart of the matter. It’s going to take some
field tests to get a good answer to that one.
(ED Note: BBNC
is a Santa Clara based company. Larry has done some contract
writing work for them and while there did indeed discover that they
had virus problems. (Norton Anti-virus discovered them.)
It is not difficult to understand Ralph’s concerns. Although
he never saw any of these viruses, out of past experience with these
folks and first hand knowledge they are reputable, we’re passing
this on for your consideration.)
Ralph P. Manfredo
President & CEO – Broadband Networks Corporation
-- Web: www.bbnc.com
This was sent to me so I thought I would forward it to your attention...
WARNING No. 1 - If you receive any CELCOM Screen Saver Please do
not install it!!!!!! This screensaver is very cool. It shows
a NOKIA hand phone, with time messages. After it is activated, the
PC cannot boot up at all. It goes very slow. It destroys your
hard disk. The filename is CELLSAVER.EXE
WARNING No. 2 - Beware! If someone named www.geocities.com/vienna/6318
asks you to check out his page. DO NOT! This page hacks into your
No. 3 - If you get an E-mail titled : "Win A Holiday"
DO NOT open it. Delete it immediately. Microsoft just announced
it is a malicious virus that WILL ERASE YOUR HARD DRIVE . At this
time there is no remedy.
Warning No. 4 - If you receive an e-mail titled JOIN THE CREW or
PENPALS, DO NOT open it!!!!! It will erase EVERYTHING on your hard
drive! PENPAL appears to be a friendly letter asking you if you
are interested in a penpal.....but by the time you read this letter
it is TOO late. The Trojan horse virus will have already infected
the boot sector of your hard drive, destroying all the data present.
It is a self-replicating virus, and once the message is read it
will AUTOMATICALLY forward itself to anyone who's e-mail address
is present in your box!!! This virus will destroy your hard drive
and holds the potential to DESTROY the hard drive of anyone whose
mail is in your box and whose mail is in their box and so on and
on!!!!!! So delete any message titled PENPAL or JOIN THE CREW this
virus can do major DAMAGE to worldwide networks!!!!
AOL HAS SAID THIS IS A VERY DANGEROUS VIRUS AND THERE IS NO REMEDY
FOR THIS YET.
wrinkle in the digital fiber
Douglas Grant, Inscriber Technology Corporation
- Web Page: http://www.inscriber.com
Technology Corporation announced that it will provide Orad’s CyberSet
with the capacity for realtime display of live data within the virtual
studio environment. Now live data for such uses as sports,
stock tickers, weather, elections and others can easily be incorporated
with the use of Orad’s virtual set.
Purported to mark an industry first, Inscriber’s contribution will
permit CyberSet users the ability to rapidly and easily change the
look of how the incoming live data content is displayed and used
within the virtual set. In addition, a major benefit is the
new capability of linking customers’ existing automation systems,
such as Drake, Omnibus and others, directly through Inscriber for
use within the virtual studio environment. Current Cyberset
users can enjoy the new benefits without having to change the way
they currently use their existing automation system.
Subj: Is 720p Hi Def?
By: Larry Bloomfield
In early June of this year
the International Telecommunications Union (ITU -- formerly CCIR),
the United Nations specialized agency for telecommunications, proudly
announced that "A major milestone in television history had
been reached." They were referring to the adoption of
a new universal electronic production standard for television programs.
The announcement spoke of a "common image format"
of 1080 by 1920 picture elements, progressive scanning, a 16:9 aspect
ratio at 24 frames per second and went on, addressing the breaking
down of various barriers that heretofore existed between TV and
cinema film production around the world. There was no mention
As technology improves and
the world tends to shrink in size, the adoption of worldwide standards
is not only commendable, but becomes an absolute necessity.
In stark contrast to this universal approach formats contained in
our, now famous, ATSC Table III. Disregarding frame rates
and the interlace/progressive scanning issues, there are three ATSC
line scanning formats -- 480, 720 and 1080. And yet
still another paradox in the HDTV arena is there isn't one European
country that has any intention of broadcasting any HDTV format,
standard or no, in the foreseeable future.
David Wood, Head of New Technology,
Technical Department, European Broadcasting Union (EBU), and an
activist in the International Telecommunications Union (ITU) told
Broadcast Engineering: "It is true to say that there
are no European broadcasters with plans to broadcast HDTV, and no
tentative plans to do so. European broadcasters are predominantly
either public service broadcasters or pay-TV broadcasters, and each
of these sectors believes, for different reasons, that the time
is not right for HDTV." HDTV seems only to be of interest
in those other parts of the world where the dominant broadcasters
are private free to air and where the priorities are different.
Since the HDTV standards here
in the United States are spelled out in the aforementioned ATSC
Table III, we started by asking Craig Tanner, Executive Director
of the ATSC what was up with respect to the absence of 720p at the
ITU. Tanner began by saying: "ATSC is not really
involved in this issue," but went on to say that he was the
head of the U.S. delegation to the Study Group 11 meetings this
past May, and as a delegation, was involved in this topic. Tanner
said that his involvement has concluded, unless he leads a future
US delegation that deals with this topic.
When press about the 720p
matter, Tanner said that it: "is an issue regarding production
formats, on which ATSC does not have a formal opinion. We have both
720p and 1080i and 1080p (at 24 and 30 frames per second) in the
ATSC DTV standard, but we have no effort underway to make judgements
about these production formats. Our emission standard accommodates
both. It is an appropriate issue for ITU-R, however."
John Reiser, an Engineer at the FCC and the US ITU chairman for
study groups 10 and 11 told Broadcast Engineering that: "For
a system to be considered 'high definition,' it is necessary for
the Hi Def system to have at least twice the number of scan lines
of the existing standard definition system." The two systems
normally considered "standard definition" are the NTSC
525 and CCIR/ITU 625 line systems and both of these are interlaced.
Reiser indicated that, at present, 720p is viewed by some at the
ITU, unofficially, as an "enhanced" television format
rather than an HDTV format, by their definition. It is obvious,
for marketing reasons, this concept just won't fly here in the US
and especially at ABC or FOX.
Glisenan of the US Department of State, a part of the US ITU team,
said he had nothing to add to what Reiser had to say on the issue.
of the possible impact this might have on ABC-TV, the 720P network,
we contacted ABC-TV's, Antoon G. Uyttendaele, Science and Technology
Senior Advisor who is also a member of the US ITU delegation. Uyttendaele
said: "It has been suggested by the ITU Radiocommunications
Assembly that only one technical standard should be recommended
for each radiocommunication application unless good reasons can
be offered to do otherwise.
"This is a very laudable
objective but hardly applicable in an environment where standard
setting activities cannot keep up with the fast pace of technology
change. Since we at ABC had no HDTV equipment at the time we had
to make our decisions." Uttendaele continued, "We
had the choice of using the 1080i format or a superior non-ITU format.
Should we have chosen 1080i just because it is an ITU Recommendation?
We (ABC) believe that 720p will deliver superior pictures to our
viewers as it is well known that interlace is a considerable source
of difficulties for all forms of picture processing, including compression."
Addressing the ATSC standards
adopted by the US broadcast industry, Uttendaele concluded:
"Since there are two HDTV formats in use in the US, the US
submitted a 720p document to the ITU to inform Administrations and
potential users of HDTV that there is an alternative to 1080i which
offers many advantages 1080i does not offer. Because of resistance
within the ITU by some of its members, notably CBS, Australia and
the UK, to recognize 720p as an HDTV production format, the SRG
on 720p (Special Rapporteurs Group) is to investigate how 720p can
become an ITU Recommendation as a second format for HDTV production.
Note that the ITU does recognize the 720p format as a delivery format
for HDTV broadcasting and that it is included in the Recommendation
for digital terrestrial broadcasting. It should also be noted that
according to Recommendation ITU-R BT.709-3, 1080i "meets the
quality goals set for HDTV". Unfortunately, we have not been
able to find an ITU document, which states what these "quality
goals" are and how it has been shown that 1080i meets these
Wood explained that:
"In terms of a definition for 'High Definition Television',
an existing ITU report (809) cites a requirement when the HDTV system
is interlaced scanned of twice the number of lines as in conventional
systems. Thus a 1080i system could be considered HDTV by this definition.
When the system is progressively scanned however, the definition
does not technically apply."
United States submitted a proposal to the ITU-R Working Party 11A,
chaired by Wood, in May of this year for a draft ITU Recommendation
for a television production standard using the 720p format. According
to Wood, the "proposal was seriously discussed, but it was
not possible to reach consensus agreement at the meeting on a draft
It was agreed that a "Special Group" would examine the
format in more depth and report back to the Working Party in February
2000. According to Wood, the special group, led by Valod Stepanian
of Iran, with Antoon.G. Uyttendaele of ABC-TV/US as co-chair is
now actively working on the issues involved. Other members of the
Special Group included Pat Griffis of Microsoft and Paulo Zaccarian
Wood says: "There are different views about the relative quality
associated with a 720p system and the 1080i/p system currently recommended
for HDTV production, but these matters will no doubt be hopefully
clarified by the Special group called SRG-720P." Wood
said that there is an alternate ITU recommendation which suggest
that: "HDTV might be considered in terms of subjectively
picture quality results, and thus HDTV would apply where the results
fall into the excellent quality band when viewed at three times
picture height. Once again, this is a matter that the Special group
may try to clarify."
to Giuliano Rossi, Senior Counselor and Head, Study Group Department
ITU Radiocommunications Bureau: "Study Group 11 (and in particular
its Working Party 11A, chaired by Mr.Wood), the ITU-R body responsible
for television broadcasting, has not ruled out the 720p format as
a potential High-Definition standard."
Rossi said that the 720p format
has been the topic of discussion at recent meetings. The focus
of these meetings, in Rossi's words, "has been on its claimed
lesser performance vis-a-vis the systems presently included in Recommendation
ITU-R BT.709-3 (which incidentally recognizes a Common Image Format
as a world-wide standard)."
When asked why 720p isn't considered HDTV, Rossi said: "The
reasons for not including at present the 720p format among the recommended
HDTV production formats were based on the lack of sufficient evidence
about its performance vis-a-vis any other system. In particular
a comparison based on subjective tests was actually considered necessary.
The above reasons have led to the establishment of an expert group
which will evaluate the system with the task to come to conclusions
in the next months."
The ITU-R has studied HDTV
over the past 15-years, starting when they were known as the CCIR.
The results of these studies are included in a wide collection of
ITU texts. Rossi said that these Recommendations and Reports
of the Study Group are available to the public and will clarify
what HDTV means in the ITU context.
Although no one at ITU would make comment on European countries
venturing into HDTV, Wood did say, "donning an EBU hat, of
course, we all know that eventually television will migrate to HDTV,
and the difference of view are largely only about timing."
The one glaring, unanswered question is: why is the ITU trying
to wag our tail in this matter?
Trivia - WHO PUT
THE N & C IN BNC?
The San Francisco SBE Newsletter
Roy Brixen, College of San Mateo and the California Council of Electronics
Instructors) It dates back to the time of World War II
at Bell Labs. Paul Neill first developed the N (Neill)
connector for radar systems. He then worked with Carl Concelman
on a connector for UHF that had a bayonet locking mechanism.
The B is for bayonet and the N and C are for their names.
The T in TNC stands for threaded.
NAB Comments on
8VSB, Receivers, CEDM's MMBS and More
In early August the National
Associations of Broadcasters (NAB) held a press conference in Washington,
DC to share their view and position about Low Power FM. In
his opening remarks, Eddie Fritz, President and Chief Operating
Officer of NAB (EF) cited that the two hottest issues of the hour
are the Satellite Home Viewers Act and the FCC's proposal on Low
Power FM. Fritz promised that once the Low Power FM issues
had been presented, the panel would address any other issues the
press might have.
All was going smooth until
Christopher Stern of Variety asked about 8VSB. Fritz politely
suggested he'd address that issue at the end of the meeting.
On the NAB side of the table,
in addition to Fritz, was a number of other of NAB's high priced
help; Lynn Claudy, Senior Vice president of Science and Technology
(LC), Jeff Baumannn, Executive Vice President, Legal and Senior
Vice President (JB) and General Counsel Jack Godman (JG).
It was difficult to identify the other members of the press in attendance.
Keeping his word, Fritz went
back to the 8VSB issue. What followed was worth sitting through
the first hour of the report just to be privy to. The gloves
came off and the fir began to fly.
Could you comment
on this COFDM?
To which Fritz asked Claudy to
LC: Claudy said
that he been to see the Sinclair demonstrations. He said,
"Our take is that the result of the Sinclair has shown are
highly colored by the receivers that they used. It's impossible
to form a conclusion that says that there's something wrong with
the system when the receivers are clearly in the loop on determining
on whether they got reception or not. So our feeling is that receiver
performance needs to be looked into very closely and very quickly.
As far as what level performance first generation receivers, as
a group, have achieved and what improvements we can expect in the
second generation, in what time frame those second generation receivers
will appear and third generation of receivers to bring the level
of performance up further. The studies that have been done
on 8VSB vs COFDM that are pure science, if you will, the analytical
studies, primarily in regards to the choices of other countries
as to weather they'll go with the ATSC system or the DVB system
that use 8VSB and COFDM respectively, don't show the big differences
that came out of the Sinclair tests.
On a theoretical bases 8VSB
and COFDM compare very favorably, but in the practical test that
Sinclair has done, they apparently don't. So there is a difference,
a gap, between the theoretical performance of 8VSB and the embodiment
of its performance in practical products, first generation products
that are on the market now. We need to understand why that
gap is there and to see how close and quickly 8VSB can get to its
performance potential. Apparently COFDM is a lot closer to its performance
potential than 8VSB products, right now and that's disheartening.
We need to understand why.
Q. What do we have to
do to understand it?
LC: I think, in a utopian
world, we would have better receivers that are more multipath immune
on the market as quickly as possible. In consumer products
there's always a time element in that development cycle to the deployment
of those products into the marketplace. The end gain is to get better
receivers that on paper are clearly possible and hopefully desmonstratible
beyond that deployable. I think we want to clearly advocate
the production of better receivers.
Q. So you're going to
sit and wait for the better receivers?
LC: I think we want
to aggressively advocate the production of better receivers in whatever
appropriate form we can find to do that.
EF: First, as I understand
that the Sinclair activity was not a test, but was a demonstration.
Point two they were testing professional prototype COFDM equipment
against first generation 8VSB receivers. There is a receiver
problem in 8VSB that is of concern to everybody. There are
very strong action steps underway to talk to receiver manufacturers
about that to talk to chip manufacturers. This is to determine
weather or not in the time frame upon during which the 8VSB receivers
can be moved to their 2nd, 3rd and 4th
generation so that there can be a complete and total understanding
of where 8VSB is vs COFDM vs the transmission standard. The Commission,
if you'll note, validated transmission standards. The commission
did not set receiver standards. I have to say that the receiver
manufacturers have failed in producing a set of comparable quality
to the transmission standard. That’s what happens when you let someone
get up and say well do you think we will not have the best possible
set available? Of course we well. We know that the broadcasters
have had the foot applied to their throats on meeting deadlines
of getting on the air, but receiver manufacturers have
not had any pressure to develop a receiver that was comparable
in quality, verifiable to the 8VSB standard. There is a committee,
MSTV which Lynn Cloudy is part of a 5 or 6 person committee making
the rounds with all of the chip manufactures and with many of the
8VSB receiver manufactures in a very short period of time on an
accelerated time schedule to determine exactly where they are in
this process and what they plan to do.
Who's going to head it?
EF: It's MSTV Engineering
committee with NAB participating.
Somebody said last
week that there is a chip that could provide a fix for all this
that could be install]ed in a TV set.
EF: What Lynn and the
other members of this committee are tying to do is to verify statements
like that and do a fact finding trips they have scheduled several
trips to attempt to find out where the 8VSB set manufacturers standards
are. I would use the opportunity again to implore the FCC to establish
standards for receivers. It has been a failing historically
recognized that the FCC has not done that. We believe because they
have not done that, receivers are not as good as they could be.
Instead if take a page from the Low Power FM book, they have decided
on their own, that the receivers are better now because we're further
down stream or we've got a digital printout rather than an analog
printout. We have no problem with Sinclair doing their demonstration.
I've spoken to David Smith. He said and I agree, that if this
spurs the industry and the FCC and lets hope the receiver manufactures
If this spurs them to action to produce something that's acceptable,
and viable under 8VSB, then let's do it. And I concur with that.
Will this controversy cause the price of sets to decline in price
as we'd hoped?
EF: I'm not so concerned
about price as I am about performance. I go back to the FCC
and say that if they want to meet the expectation levels of the
introduction of digital TV, that they have expressed, in so expressed
by putting various terms of time deadlines on broadcasters to meet
those over the air commitments which I happy to say that broadcasters,
with very few exceptions, have done an extraordinary job of getting
on the air in those markets where required to do so. We do
not have receiver standards that are comparable to what broadcasters
have produced. Let this trip that Lynn and the MSTV people
will be doing spur the receiver manufacturers into action. There's
nothing technically wrong that I've been told with the 8VSB standard.
As you know there's a Japanese COFDM standard. There's a European
COFDM standard and they're not compatible. This is being played
out in a much larger context than what we have here in the United
States. This is sort of a worldwide competition between COFDM and
If tests were to show
that the indoor tests are as bad Sinclair says they are, how bad
is that for broadcasters.
EF: We are encouraged,
quite frankly, that, one the Sinclair demos acknowledge that if
the receiver manufactures can fix 8VSB, that's fine with them.
You know what? That's fine with us. The least amount
of disruption, the better. We have to make sure that this
new era of digital television has receivers that are comparable
to the transmission standards.
Sounds like you have
some doubts. Can 8VSB be fixed?
EF: No, I don't have
a doubt about that. I just have a real gripe to air with the receiver
manufacturers. That as bout as far as I should go on this.
Any other subjects?
Do you find it interesting
that CEMA is proposing COFEM for another service -- Mobile Media
Broadcast Service (MMBS)?
LC: There's nothing
magic about COFDM. All the IVOC proposals use COFDM modulation.
Services that are inherently intended to be primarily mobile based
reception, COFDM is naturally attractive from that point of view.
So it's not surprising at all that the CEMA proposal on the MMBS
would be COFDM based.
What do you think
of the proposal itself?
JB It seems to me
the hour and a half we've spent today talking about the existing
radio service in his country and about to have a satellite radio
service, I think it's really sort of unusual, if not actually very
unusual to have someone wanting to establish a new radio service.
We're in the process of analyzing the proposal, but technically
and policy wise and will have an opportunity to have our views known
to the commission in a couple of weeks.
EF: I think it's also
interesting to note that this is one of several proposals filed
before the deadline. It is just one of what I expect to be
numerous proposals for use of that spectrum. This is spectrum
60 through 69 given up by broadcasting in this whole budget process
and in the transition to digital. I need not remind you that
this complicates low power television by order of a great magnitude
because many of the low power television stations are operating
in the 60-69 band. There are numerous educational stations
that are in that band and they're talking about something to co-exist.
We expect that there will be numerous additional proposals for use
of that spectrum that will be filed by the deadline. This
is just one proposal that will have to be analyzed in context along
with the other proposals for use of that spectrum. We'vd heard,
as obviously as you have, of other proposals that might well be
forthcoming for that.
I think our readers should draw their own conclusions
from the foregoing. LB
Although the following has little to do with digital anything,
this man played a very significant roll in the early days of television.
Many of us who have been in and around the business, on the West
Coast, have crossed paths with him. The following is from
both Larry Bloomfield and Roy Trumbull.)
John Red in Arizona *(see below) and having recorded under the name of Juan Rolando,
he was better known as Korla Pandit, the bejeweled turbaned organist
who graced the airwaves with his unique musical style. Dating
back to the early days of Los Angeles television, Klaus Landsburg,
television engineering pioneer and founder of KTLA, needed a filler
between some of his programming. In 1947, television didn’t sign
on until the late afternoons and was off by midnight, in those days
and nearly everything was live. At a chance meeting on the
Paramount lot in Hollywood, Landsburg asked Pandit if he’d be interested
in performing on the new media, but Landsburg wanted him to come
up with a gimmick. Pandit showed the next day up with
a turban from the Paramount wardrobe department and the rest is
never spoke; he just played his Hammond B-2, logging more hours
on live television than most other performers achieve in a lifetime.
Remember the early “Time for Bennie Show,” when it was hand puppets?
Pandit was the music. As television grew, the tastes of the
viewers changed and so did the performers. Pandit moved to
the Bay area and also lived for a time in British Columbia.
As Roy Trumbull recounts: “Korla Pandit was one of the TV
originals. With his jeweled turban and his haunting good looks,
he made many hearts throb. In my DJ days I interviewed him.
Off the record, he told me that a certain record companies royalty
statements weren't to be believed. He personally had sold
more of each recording that his statement indicated. One day
a moving truck came to his house with a grand piano. It was
a gift from a woman who’d been on the verge of committing suicide,
but his eyes had told here not to do it. Those were the days.”
became well know for his performances at many of the American Theatre
Oregon Society meetings and similar occasions. Those who really
knew him would always form a big smile when the announcer told the
audience that Mr. Pandit would now play his theme song from his
native land, “The Song of India.”
* Note: Since this was published in September of 1999, we have
found that all of our information is correct except that Korla
Pandit was not born in Arizona, as noted above. SSN records have shown that Pandit was
born John Redd in St. Louis, MO.
Note: The Editors and Publishers of the Tech Notes wish to
thank Des Chaskelson, Research Director of SCRI International for
his generosity in posting the Tech Notes on the SCRI web site.
Des Chaskelson, Research Director, SCRI International
The Tech Notes are published
for broadcast professionals, and others, who are interested in DTV,
HDTV, Electronic Cinema, etc., by Larry Bloomfield and Jim Mendrala.
We can be reached by either e-mail or land lines (408) 778-3412,
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