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Tech Notes

Published by: Larry Bloomfield & Jim Mendrala

E-mail = or

September 27, 1999

Tech Note - 041


Talent does what it can, but genius does what it must!

Our Mission: Sharing experiences, knowledge, observations, concerns, opinions or anything else relating to Electronic Cinema, DTV, etc., with fellow engineers and readers. We do hope that everyone will participate with comments, experiences, questions and/or answers.  Please note Jim Mendrala's new E-mail address. Phone numbers and other stuff that used to be up here is now at the end of this newsletter. We now have over 480 subscribers & growing.                 

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Subj:  DTV Construction Notes

By      Roy Trumbull

(Ed note: Roy Trumbull, Asst. Chief Engineer at KRON in San Francisco. 

The 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.

What 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.

If 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.

A 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.

Using 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.

How 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 NoteBBNC 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.)

Subj:  Warning

From: Ralph P. Manfredo
President & CEO – Broadband Networks Corporation
Email: -- Web:

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 asks you to check out his page. DO NOT! This page hacks into your C:\drive.

Warning 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!!!!



Subj:  Another wrinkle in the digital fiber

By:        Douglas Grant, Inscriber Technology Corporation

E-mail: - Web Page:

Inscriber 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.
Douglas Grant


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 of 720p.

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. 

John 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.

Because 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 goals."

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."

The 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 Recommendation."

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 of CBS-TV.

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."

According 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?           LB


Subj:  Trivia - WHO PUT THE N & C IN BNC?

From:  The San Francisco SBE Newsletter

(From: 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.


Subj: NAB Comments on 8VSB, Receivers, CEDM's MMBS and More

By:      Larry Bloomfield

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.

Q.    Could you comment on this COFDM?

R.      To which Fritz asked Claudy to respond. 

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. 

Q. Who's going to head it?

EF:  It's MSTV Engineering committee with NAB participating.

Q.    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.

Q. 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 8VSB. 

Q.    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.

Q.    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?

Q.    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.

Q.    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


(ED NoteAlthough 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.)

Subj: Korla Pandit Dies

Born 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 history. 

He 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.” 

Pandit 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.


(Ed 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.     

From: 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, (661) 294-1049 or fax at (419) 710-1913 or (419) 793-8340. The Tech Notes are sent (BCC) directly only to those who have asked to be on the mailing list, however feel free to forward them, intact, to anyone who you think might be interested. There is no charge for this Newsletter, no one gets paid (sigh), there is no advertising and we do not indorse any product or service(s).  The ideas and opinions are those of the individual authors.  We still administer everything manually.  We don't use any "majordomo" automatic servers. News items, comments, observations, opinions, etc. are encouraged and always welcome. We publish when there is something to share.  Material may be edited for brevity, but usually not.  Tech Note articles may be reproduced in any form provided they are unaltered and credit is given to both Tech Notes and the originating authors, when named.  If they are to be used by a publication that normally compensates their writers, please contact us first.