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DTV Tech Notes

% Larry Bloomfield & Jim Mendrala

(408) 778-3412 or (661) 294-1049

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June 08, 1999

DTV Tech Note - 031


Talent does what it can  -- Genius does what it must!

What are we about?  The sharing of experiences, knowledge, observations, concerns, opinions or anything else relating to Electronic Cinema, DTV, HDTV, etc., with fellow engineers and readers.  We publish when there is something to share.  We only send the DTV Tech Notes directly to those, like yourself, who have asked to be on our mailing list, however feel free to forward them, intact, to anyone who 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 don't use any "majordomo" automatic servers.  We administer everything manually.  We do hope that everyone will participate with comments, experiences, questions and/or answers.  We now have over 390 subscribers and growing.  This is YOUR forum! 

Past issues are available at: WWW.SCRI.COM


Subj: A handy tool
From: Roy Trumbull  >> <<
(Ed Note: Roy is Asst. Chief Engineer at KRON Channel 4 in San Francisco)

The IOT tube is best setup measuring current rather than voltage. There is the filament current and the focus coil current to name just two. Both of these are DC. While AC clamp-on ammeters have been around for ages, it's only recently that affordable DC clamp-ons have become available. A DC clamp-on uses a hall effect sensor.

The Extech 380947 ( has a 40A and a 400A DC scale as well as 4A, 40A, 100A, and 400A AC scales.  This is a really handy meter to have. I was trouble shooting a problem in an RF driver. Using this meter I was able to check the current flowing to each stage by clamping onto the supply leads. I traced the trouble to a preamp. I figure the meter paid for itself on that job.

Roy Trumbull


Subj: Entertainment Technology Center
By: Jim Mendrala

According to Jim Korris and Thomas MacCalla, the Entertainment Technology Center (ETC), a sponsored, organized research unit of the University of Southern California (USC), has entered the Electronic Cinema "Cloud" at the behest of its members and Executive Board. They will take a two pronged attack for this initiative. Technology and Business focus. While they do not, as a rule, intrude on matters of pure commerce, many of the technology issues in E-Cinema will be determined by market-place considerations...hence the dual focus.

Jim Korris and Thomas MacCalla in a mission statement said that what they hope to accomplish is:

1. A Single Standard

A single Standard would be most efficient. The industry has benefited for decades from the standardization of the width of 35-mm film. If we can agree on a single standard it will fall
to equipment manufacturers to accommodate the spec.

2. Security

Whatever the transport and storage medium, digital filmed entertainment assets are likely to more physically portable than reels of film. Copyright protection and anti piracy measurers are of the utmost importance.

3. Compatibility

We must be certain to provide for inevitable future improvements and refinements to the hardware of video projection. Accordingly, whatever hardware goes into theaters today must be capable of playing future releases without the need for the production of multiple formats,

4. Consensus

There are four communities - each of which will be significantly affected by the deployment of Electronic Cinema - that should have a voice in this process: - distribution, engineering, exhibition and film making. Accordingly, we are approaching representatives of each group as the agenda

It is fair to say that Electronic Cinema is, if not imminent, certainly foreseeable. With the free and open exchange of ideas that we hope to encourage, its arrival will bring greater expression, increased efficiency and new opportunities for all participants in the medium.

Subj: Something to say?  

By:    Larry Bloomfield

If we can help just one reader with something he or she didn't know or share with them something that will help them do their job better, all this time and effort is worth it!  This is why we ask that if you have some thoughts, ideas, different or better ways of doing things in digital television, electronic cinema or related areas of interest, share them with others.  If you have trouble putting your thoughts down, I'm more than happy to assist you. If you need anything written or classes prepared or taught, you can also contact me and I'll help you with it. God knows I have the time right now.


Subj: Some thoughts from Down Under
From: Peter Corbett - Powerhouse Productions

Melbourne, Australia >> <<

I'm a video producer in Melbourne, Australia. We are currently evaluating different systems for the migration path to digital. My technical knowledge is not extensive, but I have some thoughts about HDTV, which may be of interest.

I recently went to an elaborate HD demo by Sony at AAV in Melbourne. While HDTV is still in it's (mainstream) infancy, the results were a bit mind-blowing. It was all 1080i/60 and looked tremendous on large-screen 16.9 projectors.

Colour and detail was almost film-quality, certainly better than any video format I've seen. Fine detail in forest shots or crowds had tremendous detail and clarity. Skin tones and fidelity was excellent. In close-ups, every pore was sharp. Maybe too sharp!

The synced Standard Definition picture running alongside the HD screen was also quite sharp but the scan lines were VERY distracting.

But the biggest disappointment was the Digital Betacam upconverted to 1080i running simultaneously on a third screen. I'm afraid it looked like analog SP compared to HD. Detail was lost with a softish picture spoiled by ringing and detail artifacting. With the price of the new Digi-beta cameras coming down, I was (and still am to some degree) tempted to go Digi-beta, but now....

The best bit is that for us here in Australia, 1080/24P will arrive here in Australia at the start of 2000. This will truly be a world-standard, with one machine capable of inputting and output all world HDcam standards.  The 24 frame progressive standard will allow much greater interchange between traditional NTSC and PAL markets. It should also keep hardware prices down. One other neat bit was that the first 24P HDCAM VTR, the HDW-F500, will also play back Digi-beta and SX with an optional board.  The upconverted quality remains a problem for me though.

I think HD will take off tremendously once episodic television and feature production starts to migrate over from film. The question is not whether the rest of us can afford the cost of moving to HDTV production, but whether we can afford not to.

Peter Corbett


Subj:  Whatever to do with the FAA.

By    Burt I. Weiner   >> <<

I believe this would be applicable to any transmit facility.  Please share it with your readers. 

A client station recently ran into a problem with the FAA as a result of an FCC inspection. It seems this station had lost a beacon due to the recent rains.  The FAA had been properly notified, or so the station thought.  The station's operators had called the FAA 3 times because 3 different operators thought they were supposed to call every day.

The FCC coincidentally inspected the station.  During the inspection the tower beacon light situation came up.  The FCC inspector was shown the entries in the log made by the operators for all three times.  The entries showed the date, time and name of the person they spoke to at the FAA.  Interestingly enough each caller got the same FAA person on different days.

Several days later when the FCC inspector called the FAA to confirm the report, the FAA had no record of the reports.  It took a long time to track down what had happened. 

It seems the person taking the report was not given the proper type of "exact location" when he asked for it.  As a result he didn't file the report.  The people at the station each claim the FAA person taking the information said, "I'll take care of it".  No further questions were asked.

The FAA does not keep their telephonic recordings beyond 15 days, sometimes less than 15 days.

After speaking to various people at the FAA I discovered they want to know where the tower/s are in relationship to a navigational aid.  Some say coordinates are good, some say not.  It just depends on whom you talk to.  The one thing they all agree on as being a good "exact location" is a bearing in degrees and distance in nautical miles from the nearest navigational aid.

If you don't already have this information posted along with your reporting instructions, it wouldn't hurt to call the FAA and find out what wording they recommend for your particular tower/s exact location.  Copy it down word for word and add it to your reporting instructions.  I suggest giving the tower coordinates as shown on your station's license as additional information.  It couldn't hurt.

Be sure to have the person phoning in the report get the full name of the person taking the report and be sure to enter that person's name as well as the time of the report on the station's log. 

Burt I. Weiner

(ED Note: The smart money says to also send a written confirmation of the phone call.  Be sure to including all details of the antenna location and all other relative information, along with the name of the person with whom you spoke to at the FAA, to the FAA office in question via Certified Mail with a return receipt requested. File copies of you confirmation letter with copies of the return receipt in the various logs near where you made the proper entries)


Subj: SMPTE Task Force On Electronic Cinema
By:   Jim Mendrala

The Society of Motion Picture and Television Engineers (SMPTE) has announced the formation of a task group to examine areas of needed standardization for electronic cinema to become a reality. Recent demonstrations have shown how rapid has been the improvement in technical quality from electronic projectors. This has opened the gateway into the probability of a complete electronic cinema system. A complete system, however, contains a large number of transmission and storage elements that require industry wide discussions.

The SMPTE is creating a Task Force, charged with a brief to identify areas of the system that requires standardization. The group will not be responsible for actual standards documents. Those will be structured by the relevant SMPTE Engineering Committees, including the existing Electronic Projection committee. This is hoped to enable a fast track approach to the issues, with different groups of experts working in parallel.

Obviously, something as revolutionary as electronic cinema affects the whole movie industry and consequently the SMPTE is taking steps to include as many sectors of the industry as possible. In addition to the announced electronic cinema proponents, participation is being invited from members of key industry trade groups, including ASC, DGA, ITEA, MPAA, and NATO. The Electronic Cinema Task Force will report to the SMPTE Film Steering Committee P3.

Subj:  The Best Government Money Can Buy!

By:     Larry Bloomfield

Our elected representatives' coffers have been enriched by over half a million dollars in contributions.  Members of the Senate Commerce Committee got some big bucks from some very familiar sources. $141,900 came from the National Association of Broadcasters, ranking NAB as the 10th top donor, followed by the National Cable Television Association who kicked in $135,067, putting them in the No.11th position.

The NAB, the NCTA, and some of the companies they represent in Washington, D.C., are some of the largest donors, when the data is broken down to committee-related contributions, to key members of our nation's House and Senate.

This information, obtained from public record (-the Federal Election Commission's data released on February 1, 1999-) was compiled by the Center For Responsive Politics.  .

The NCTA must feel stronger about members of the House Commerce Committee as they "contributed" $191,746, ranking them No. 3, in that branch, where as the NAB came in only 14th with contributions to the House Commerce Committee members to the tune of only $121,919 in contributions. Just in case you didn't know, the House Commerce Committee and its Telecommunications Subcommittee are the key lawmakers for broadcasting, communications and satellite-related legislation. 

Who's Numero. uno? -- AT&T, who recently entered the cable-TV business when they "acquired" Tele-Communications Inc.  The Center's report stated that AT&T always gives $204,950 to Senate Commerce Committee members.  Does it do any good?  You'll have to ask them, but it sure does put a whole new twist onto: "We gave at the office."  And, who is it that said,  "We will have the best government money can buy"?  Excuse me, I think I'm going to be sick now.


Subj:  VESA Adopts Digital Flat Panel Standard

By:     Jim Mendrala VESA Adopts Digital Flat Panel Standard

The Video Electronics Standards Association (VESA) has ratified the Digital Flat Panel (DFP) standard. This standard provides for a single video connector to digital LCD monitors and projectors.

This standard makes use of the Transition Minimized Differential Sampling (TMDS) electrical standard, the VESA Display Data Channel (DDC) standard, and a low cost 20 pin physical interface to the flat panel display. The DFP and the VGA connector will let PC manufacturers market flat panel enabled systems while maintaining VGA analog functionality.

Many companies are rallying around the standard such as 3dfx Interactive Inc., 3Dlabs, 3M, Compaq Computer, among others.

This isn't the first time TMDS has been used in an interconnect standard for a display. Two years ago, VESA based its Plug and Display (P&D) standard on the Panel Link Technology from Silicon Image, Cupertino, California.

Will this become a standard for consumer DTV receivers using Flat Panel Displays?


Subj: Error Noted in DTV Tech Note #30 - What's Going On In The DTV World

By: Jim Mendrala

Charlie Pantuso correctly noted that it is 1035 lines not 1034. I don't pull these things out of thin air.  SMPTE 240M-1995 states in the Annex A paragraph A.5 on page 7 the picture boundaries.

"The production aperture defined by this standard comprises a picture made up of 1920 reference clock periods horizontally by 1035 lines vertically. The 1920T width of this analog production aperture is specified at 50% video level, and represents the maximum active video permissible under this standard.......This analog production aperture has identical dimensions to the digital production aperture of ANSI/SMPTE 260M."

I don't know what happened.  At first I thought 1034 was a typo but it was repeated three times. The 1125 came out right though.  I type that article on my old computer and come to think of it, it has screwed up a few times recently.  Maybe I have an intermittent keyboard.  I'm glad somebody reads the Tech Notes that caught this. Thanks for bringing it to my attention. Jim


Subj:  VidTranS 99 Conference Addresses Telecommunications for Digital Video

From:   Matthew C. Peterson >> <<

VidTranS 99, a conference and exhibition designed to address the needs of the converging areas of broadcast and telecommunications will be held October 4-7, 1999 in Los Angeles, California. This year's conference focuses on the opportunities, challenges and technologies presented to the video transport industry by the growing use of digital video in broadcast, cable, satellite and WWW television. For information on attending, speaking or exhibiting visit

Matthew C. Peterson


Subj:   Trade Shows

From:  SCRI

(Ed Note: The following SCRI note is our way of saying thanks for them letting us use their web site.)

SCRI's online coverage of key broadcast / pro video Trade Shows continues with new press releases on SCRI's NAB '99 site, as well as on SCRI's Montreux '99 site.

Press releases remain on the site all year providing broad exposure to the thousands of broadcasters and pro video facilities that visit the SCRI site every week.  Manufacturers wishing to have their information and press releases listed should contact -- 6 line listings are provided free (prior to the show) -- full press releases at a nominal cost.

NAB99 Press Releases -

Montreux  Press Releases - June 10 - 15 '99 -


Ed Note: Jim Mendrala is in Atlanta this week and will report on the goings on there.  It should be quite interesting. Larry has some really interesting things coming out in the June edition of Broadcast Engineering.  If you don't have a subscription to BE, you can catch it on the web at


The DTV Tech Notes are published for broadcast professionals, and others, who are interested in Electronic Cinema, DTV, HDTV, 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 (661) 294-0705.  (Note - Jim's new area code is 661). News items, comments, observations, opinions, etc. are encouraged and always welcome from our readers; material may be edited for brevity, but usually not. DTV Tech Note articles may be reproduced in any form provided they are unaltered and credit is given to both the DTV 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.