Archived Tech-Notes
Published by: Larry Bloomfield & Jim Mendrala The following are our current e-mail addresses:
E-mail = hdtvguy@garlic.com or J.Mendrala@ieee.org
We have copied the original Tech-Notes below as it was sent out. Some of the information may be out of date.
**********************************************North West Tech Notes % Larry Bloomfield & Jim Mendrala
521 Forest Grove Dr.
Bend, Oregon 97702
(541) 385-9115Email = larrybend@aol.com
J_Mendrala@compuserve.com---------------------------------------------------------------------------
--------------------------------------------------------------------------June 28, 1997
NWTN - 005---------------------------------------------------------------------------
---------------------------------------------------------------------------Sorry it took us so long to get this issue out, but it has been a week and a half you don't want to hear about. Please keep in mind that this effort will be successful ONLY with the assistance of those who help by contributing information to us and have the professional desire to keep us all on the cutting edge of this technology. So, we need you to share your experiences, knowledge or anything else relating to this area of our industry. We will share what we get from you. This is a work of love. We see a need and we're doing this solely with the idea of keeping ourselves and our associates informed. We ask no compensation for our efforts, just the latest information you may have on what's going on. We will not pass on anything that cannot be verified or the source cannot be identified. If we inadvertently pass on erroneous information, we will make every effort to get it corrected as soon as possible. The above disclaimer is for obvious reasons.
Who will we send these issues to? We will make every effort to share this effort with our fellow broadcasters: Anyone interested!. Just e-mail us your request to be added to the mailing list and it's done! Feel free to forward this on to your associates, but let them know that you've done so and it's not directly from us. If have sent this to you and you're not interested, just let us know and we will take you off the mailing list.
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Subj: What others are saying and some comments
by: Larry Bloomfield
The front pages of the June, '97 issue of Television Broadcast, addresses what they think transmitter Manufacturers are saying about being ready to deliver their product. I'd like to add to their list of transmitter manufacturers who they say will be building transmitters (in alphabetical order: Acrodyne, Comark, Emcee, Harris, Itelco, ITS, and Larcan) the name of Continental-Telefunken, a joint venture which joins together the well known radio transmitter manufacturing company with one of Europe's oldest electronic firms.
Next to this is a story about the lack of equipment available at this years NAB for local origination. They quoted Pat Holland, Vice President and Director of Engineering at KOMO-TV in Seattle, (who has been too busy to return our calls) commenting on the transition into HDTV. It sounds as though he is having his problems. There are many questions we'd like asked of these big market leaders who, like it or not, are paving the way for the vast majority of us. If we can get this dialogue going, as NWTN is intended to do, it might be possible that some of our readers might have some easy solutions to their complex problems. We (NWTN) would sure like to help. We have also been, unsuccessful, in reaching Bob Levin, Director of Engineering at Direct TV in Colorado. We know these key people have much they can share with us without compromising proprietary information.
Jim Mendrala, co-editor, co-founder and contributor to the NWTN, attended most of the meetings that Craig Birkmaier mentioned in his article with the sub-title: What's Wrong With These DTV Pictures? As you have read here, there is much confusion and a general lack of direction in what to do and how to do it. This was even more graphically illustrated in a broadcast of a panel discussion about DTV from Portland, OR this past Friday (6/27/97) on Oregon Public Broadcasting. It sure sounded like the blind leading the blind and I know these folks were well intentioned. If you can get a copy of this nearly hour long program, listen to it. I have no doubt that you'll agree and I hope not be too embarrassed for them.
The June 5th issue of TV Technology points out what many of us with translators figure will happen and that is we'll loose some of our facilities to the new allotments for DTV channels. Despite the penetration of Direct broadcast Satellites, there are many viewers who still depend on translators for news, the Emergency Alert System and the source of their entertainment. This is not to mention the great service LPTV does also in this area. I didn't even remotely appreciate or understand these important facts of life until I moved from Los Angeles to one of the very smaller TV markets. Perhaps the FCC in Washington, DC doesn't understand what they are doing to these folks either. May be the FCC policy makers would think differently if they were views of a translator because they couldn't get the main station due to geography. It wouldn't be the first time the FCC didn't under radio frequency propagation and the geography of a mountainous areas.
Permit me to being a few things up that may be perhaps hard lessons learned and perhaps best forgotten. BETA vs. VHS --- KAHN vs. SEQUAM --- PC vs. MAC --- Alpha vs. Omega wrap (tape). I'm not sure if I got all the spelling correct, but you know what I'm talking about. If you don't, you'd better find out. There are probably other systems and/or standards I could mention, but I think I've made my point. Here's another one --Perhaps the term: "Let the market place decide" will bring back shivers to any good engineer's spine. Well to sum this all up, we have been stuck, for various reasons, with inferior standards because unqualified, incompetent marketing types have forced these things on us. By the way the PC vs. MAC was used just to get your attention, I use both.
In the early days of our television industry, engineers called the shots. When we (engineers) had perfected the system, it was turned over to the programmers and our industry took off, making history and big bucks for a lot of folks. How short memories are. We are in an almost similar situation. We engineers can do it again, if left alone and allowed to apply our talents. Congress has told us they want an improved television system, the FCC has told us where we can do it, but not necessarily how and now it's up us, the engineers, again, to perfect a system we can all afford and live with --- without compromising technical integrity. Cooperation and interchange of information was the way it was done in the early days and it should be that way today.
If you will recall, we touched on the lack of programming in our last issue. Well it stirred up some feedback It seems that there is a company in Texas which has been producing
"Digital High Definition" television for the past eleven years, or so they said. We were informed that they have done this in about every format requested. We believe there-in, lies the problem -- "in just about every format requested." We were addressing: What are the broadcaster going to finally settle on." We've heard stories about: progressive scan -- interlace, 4 by 3 -- 16 by 9 aspect ratios. It's time to roll up our sleeves and get to work and stop talking. I've heard that standards are too confining. My answer to that is that the phone company had a set. They called them the "BSP" (Bell System Standards) which was the back bone of probably the greatest telephone system on the planet. Change or deviation from a standard on occasion is acceptable, but how do you know where you are if you want to make a change if you have nothing to reference?
We are aware that the direct satellite broadcast people have been transmitting digital, but it is not the high quality, crystal clear picture stuff we've told the public we want to give them. Although, yes, it is a studio quality picture, it is still 4 by 3 aspect radio, 525/30 interlace composite picture and not the hi quality 1920 by 1080 pixels (progressive scan) in a 16 by 9 format. We can however learn from the "Direct" folks the parts of DTV we would like to employ in our new broadcast systems. After all they do have and are using the decoders that we may very well want to use to accommodate the folks who don't have one of the new receivers not yet available and as a stepping stone to the future.
Your input is most graciously welcomed.
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Subj: HDTV Programming
From: Michael Silbergleid, Editor - Television Broadcast / Miller Freeman PSN
460 Park Ave. South, 9 Fl. - New York, New York 10016212-378-0415-phone / 212-378-2160-fax / silbergleid@psn.comhttp://www.tvbroadcast.com
Read your viewpoint about HDTV programming. One thing you forgot is that all prime-time programming shot in film is now archived in HDTV. One of the problems that European broadcasters doing PAL-Plus (wide screen PAL) was that they thought there was no wide screen programming. Surprise ...the prime time shows they were airing were available in wide screen (they are shot full aperture).
If station programmers ask the syndicators/studios if they can get an HDTV
dub, I think they might mind the answer is "yes."---------------------------------------------------------------
Subj: The above letter from Michael Silbergleid, Editor - Television Broadcast
From: Jim Mendrala
Some comments on the preceding e-mail we received.
You are absolutely correct when you say that practically all prime-time programming is shot on film. It is something like 80%. Film contains an image that is of a higher resolution and contrast than HDTV can provide. As to being archived on HDTV, not yet. What Hollywood does now is to frame the shots for the 16:9 format and photograph the images in full aperture onto 35 mm film. Some popular shows have been shot on 16 mm and Super 16 but the resolution is below HDTV resolution. Therefore producers have been told to convert to 35 mm. A letter box for true 1.66:1 or 1.85:1 is minimal. Since the film is shot in full aperture and framed for 1:66, 1.78 or 1:85 it will play on HDTV very well.
What is full aperture in the camera? It is 0.980 inches (24.9 mm) by 0.735 inches (18.7 mm). This is a 1.33:1 aspect ratio. It is called full aperture because it makes no room for an optical sound track. 35 mm film with a sound track is called Academy Aperture. Academy Aperture is 0.825 inches (20.96 mm) by 0.600 inches (15.24 mm). For example when film is shot 1.85:1 for a theater presentation it is composed and framed for a 1.85:1 aspect ratio but photographed in full aperture onto the film. To use these films for HDTV
they would have to be transferred on an HDTV telecine. CBS plans to have an HDTV telecine on the East coast and West coast in the near future so they can start converting these films to HDTV.There are hundreds of film vaults in Hollywood that contain perhaps 1000's or more films that could be used for HDTV programing. But, they will all need to be transferred to HDTV on a HDTV telecine. A small number of films are "hard matted" for the aspect ratio of choice by the cinematographer. A "hard matte" is an aperture plate that can be installed in the camera so that it will photograph only the aspect ratio of choice. Optical printer operators and CGI people would rather have full aperture to do there tricks. Full aperture gives them more flexibility.
JM
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Subj: DTV/HDTV and Microwave Systems
By: Peter Finch
Northwest Communications (503) 632-7488
(Ed Note: Peter has his own newsletter. Since some of our readers are on our list also, please excuse the duplication of efforts at this end.)
Several more broadcasters have been added to this News Letter data base. As such, I decided to summarize the shared information so far.
Thank's to the many of you who have responded with questions. I hope I have answered them to your satisfaction. To everyone, if you have any questions, please do ask. We are all in a very steep learning curve and them are absolutely no dumb questions!
DTV microwave recap:
Antenna systems should be designed for minimum VSWR as reflections can result in bit errors. Antennas should always be Low VSWR type. Those of you who have purchased antennas through Northwest Communications should be fine as I have always quoted Low VSWR antennas. If possible, waveguide systems should be of the "premium" variety. There are some problems here. A premium waveguide/connector assembly needs to be
swept and the required test equipment is expensive. It is possible to avoid the sweeping by ordering the assembly as a swept system with the connectors attached. This means that the hole in the building wall will have to be bigger to allow for the connector. Also, having to reattach a connector in the field puts you back in the sweeping problem. I have yet to find a solution to this problem.The MRC "DAR" radios are digital and analog compatible. DAR stands for "Digital-Analog Radio". A DAR radio is basically a heterodyne radio which has been linearized for digital use. Being a heterodyne radio, the input or output is at 70 MHz. Fortunately, the digital modulator or demodulator is also a 70 MHz in or out device. A DAR radio is equally at home in the analog world. It merely requires the inclusion of a 70 MHz modulator (FMT)
or 70 MHz demodulator (FMT). These are cards that are inserted into the DAR radio to allow for a baseband input or output.DAR radios are available right now. The digital modulator and demodulator is also available at this time. The digital coding used is QPSK at 34 Mbps. This allows the signal to fit into a standard 25 MHz microwave channel. This also means that 2-GHz may not be DTV compatible with the 15 MHz channels coming in 2000.
Since DAR radios are totally at home in both the digital world and the analog world, it is suggested that all radios purchased be DAR type.
Several digital multiplexers will soon be on the market. These will enable you to combine several digital TV signals into a single bit stream before modulating onto the microwave system. I have been told that at least one of these multiplexers should be available around August of this year. At that time I will be able to quote them to end users.
I believe that covers everything we have looked at before. Everyone should be at the same point. As I get more information, I will share it via this News Letter.
PF
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YOU kill what YOU fear and YOU fear what YOU don't understand. (James S. Kaplan)
Ed note: Who understands DTV?
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From: Tom Pearson, KTVZ
Subj: Something I saw on the internet
Thought you might find this interesting, it's about a DTV carrier "going dark"
From: bhk@dsl.co.uk (Brian {Hamilton Kelly})
In article <NEWTNews.866479766.26951.bnbbsy@bnbbsy.eunet.be> bnbbsy@news.belgium.eu.net "SY/NW BNB" writes:
Where may I find the codes for Canal+ 4/3 on TDF. Canal+ on telecom will be soon stopped. You can't, I'm afraid. Unlike the 16:9 broadcasts (which I had been under the impression had *already* stopped), the 4:3 ones are intended only for cable TV distribution. As such, the only official cards are those issued to cable head-end operators, and thus there has been no opportunity for discovering the codes used :-( This question is asked at least once a month: the answer, unfortunately, has always been the same.
(Unless, of course, someone else knows different!)
Maybe some of your readers will comment.
Tom
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The NWTN is published for broadcast professionals who are interested in DTV, HDTV etc. by Larry Bloomfield, Chief Engineer, KTVZ, Bend, Oregon and Jim Mendrala, Consulting Engineer, Val Verde, California. We can be reached by either e-mail or land line (541) 385-9115, (805) 294-1049 or fax at (805) 294-0705. Thanks to the folks at Communications General Corporation for inspiring us to do this. News items are always welcome from our readers letters may be edited for brevity.
larrybend@aol.com --------- J_Mendrala@compuserve.com
NWTN articles may be reproduced in any form provided they are unaltered and credit is given to the North West Technical Notes and the originating authors, when named.
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