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 Some of the information may be out of date.
**********************************************Tech Notes
Published by: Larry Bloomfield & Jim Mendrala
(408) 778-3412 or (661) 294-1049
E-mail = larrybend@aol.com or J_Mendrala@compuserve.com
August 23, 1999
Tech Note - 038
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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. The other stuff that used to be up here is now at the end of this newsletter. We're growing. We now have over 465 subscribers.
This is YOUR forum!
Past issues are available at: WWW.SCRI.COM
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Subj: DTV STL, Fixed Link Systems
By: David O. Thomas, VP of Sales & Marketing Nucomm, Inc.
With the November 1, 1998 HDTV official launch date in the USA come and gone, much has been learned about Microwave HDTV STL systems and their performance. Two years ago we were all wondering how we were going to transmit our HDTV and NTSC signal out to the transmitter sight. At the time of writing this article many HDTV STL systems are in place and working.
When planning your HDTV STL, there are several key areas you must concern yourself with. First we will look at data rate through put capacity and second Modulation formats. It is important to understand the relationship and tradeoffs between the modulation formats used and the data rate through put capacity the modulator can provide versus the performance of the link or Fade Margin. For example, the modulation format QPSK offers an excellent robust signal (better than analog). However, its data through put capacity is limited compared to other digital Modulators. While on the other hand, 16QAM offers high data rate through put but the link performance is worse than that of an analog link.
This is only a few paragraphs of the full 17-page article that concerns itself with all digital microwave HDTV STL systems. There are systems that can carry both an analog and digital video signals on a microwave channel but this system will be discussed in a future article.
There are typically two types of “all digital” HDTV STL systems. One system transmits just the 19.39 Mbts ATSC signal or while the other carries both the ATSC and MPEGII NTSC encoded signal. In the second case, an encoder is required to digitize the analog signal and than combine or multiplex it with the ATSC signal. In either case, different data rates will be used thus giving you the option to decide on which modulator format will give you the data through put and link performance or Fade Margin required.
In cases were a second microwave channel is not available, the ATSC and MPEGII encoded NTSC signal are combined on to one microwave channel. Therefore, the link will operate at a higher data rate. It is typical to run the MPEGII encoder at 15 to 20 Mbts and achieve excellent video quality. Combine this data rate with the 19.39 Mbts and the result is 34.39 Mbts.
In the full article, we talk about the different HDTV STL System types that are available, how to determine data through put capacity and how the modulator determines the link performance and data rate through put capacity. These tools will allow you to determine which system will work for you.
Having a second STL channel can certainly make life easy for you but most folks will not be so lucky. The “Dual Digital” and “Dual Stream PLUS” systems will allow you to send both your NTSC and 19.39 ATSC signal down one microwave channel.
The modulator plays a vital roll in the STL link by determining the data rate through put and system performance. You will have to take a look at your situation and determine what is more important, performance vs. data through put. Remember QPSK will give you the best performance but limited data capacity whereas 16QAM gives you high data through put but your system performance will suffer.
Since we are traveling uncharted waters, it may be wise to select a system that gives you the most flexibility as possible such as DTV STL systems with open architecture platforms. This will allow you to change rapidly to the ever-changing Television market place. Flexibility can come in the form of many things. For example, several modulation types per modulator or a Dual Stream system that can change to a Dual digital system with little problem.
For the full article on this subject matter and other interesting tidbits, visit Nucomm's web site: www.Nucomm.com
David (not the Wendy's guy) Thomas -- Nucomm, Inc.
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Subj: Nielsen Can Be Bought!
By: Larry Bloomfield
The impact of this could have very deep reaching consiquences in all the American Broadcast industries and should not be dismissed lightly. According to a miryad of press releases back on August 16th, a Dutch publisher, VNU has reached an agreement to buy the well know media research company, Nielsen for a tidy $2.5 billion -- that's billion with a "B". Including Nielsen's net debts, the deal is said to be worth $2.7 billion. The offer commenced on August 20 and expected it to close in the autumn after normal US regulatory scrutiny and approvals.
If you are one of the two or three people in the business who don't know who they are, Nielsen is the company that measures television audiences and internet use. Remember, it is how many eyes and ears a station can deliver to an advertiser that determines what can be charged for a network or local spot. Nielsen plays a very critical roll in this processes. Nielsen also plays a major roll in determining the DMAs which the FCC uses in determining duopoly rules etc.
It is important to note that the FCC has very stringent rules on foreign ownership of broadcast stations and now a foreigh organization will be running the organization that spells out who is watching what and when, which determines the financial wellbeing of the American broadcast industry. Interesting dicomoty, to say the lease.
Nielsen has 3,300 employees and grossed $408 million in 1998 with earnings before interest, tax, depreciation and amortization of $126 million. A. C. Nielsen offers services in over 90 countries and reports its 1995 revenues as $1.4 billion. They say they are a global leader in delivering market research, information and analysis to the consumer products and service industries. On the other hand, Nielsen Media Research has been part of the Cognizant Corporation. According to their web page, they say their primary concern is media measurement across the United States and Canada.
You may find more information at http://www.nielsen.com
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Subj: HARRIS OPEN HOUSE
By: Larry Bloomfield
Names like Gates, GE, RCA and others have come and gone in the broadcast arena, but Harris is one that's still with us. In fact they're a relative new comer. According to information recently received, "It's year 15 for the Harris radio and TV Open House to be held at our new 165,000 square foot "Center of Excellence for Digital Technology" in Greater Cincinnati, Oct 1."
The bash sounds like something that, if you were in the area, would be worth visiting. There is no charge for admission and the event will feature tours of their new engineering and integration facility. Attendees will have the opportunity to meet factory people and see demos from Pluto, Sony, SAS, Telos, Comrex, Vinten, 360 Systems and 40 more radio and TV suppliers. For additional information and registration, call 800-622-0022. The contact name supplied from Harris is that of Dave Burns, Harris
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Subj: It's about time and STBs
By: Larry Bloomfield
The cable industry has been dragging its feet in getting what is necessary for an OpenCable or interoperable set top box (STB) ready in time to meet their FCC designated deadline. CableLabs is an exception to this statement. Most manufacturers have been pushing for priority technology that would have everyone else come to them for the rights to use the infrastructure. Shades of DOS and Microsoft. CableLabs has managed a project that seeks to facilitate the development of advanced digital devices from multiple suppliers that will communicate, or inter-operate, with one another. The project is working to achieve a retail available set-top box or integrated television set that employs a point-of-deployment (POD) module by the July 1, 2000, deadline established by the FCC. Additional interoperability events are scheduled to help meet FCC deadlines.
In preparation for these future interoperability events, CableLabs issued a request for information (RFI) that seeks to identify companies interested in providing set-top boxes, integrated television sets, or computer cards as part of OpenCableÔ interoperability waves starting in September. The RFI is available on the CableLabs website (www.cablelabs.com). Although the date for this is now past due, if you really think you have something worthwhile, it might be in your best interest to contact Paul Zimmerman, systems integration manager for CableLabs as soon as possible. If you've got something that would save the world from famine, world war and bring copious amounts of "yenom," that's money spelled backwards, I'm sure they'll bend over backwards to accommodate your widget.
Cable Television Laboratories Inc., better known as CableLabs of Louisville, Colorado have been working with a number of manufacturers in an area that focuses on removable security cards that allow for retail availability of cable digital set-top boxes. The roll call included names like: General Instrument, Mindport, NDS, Nagra, Philips Electronics, SCM Microsystems, and Scientific-Atlanta. Approximately 40 representatives from these companies were at CableLabs during the week of testing. CableLabs expects to attract additional supplying companies to future interoperability events. Many of the firms that demonstrated this functionality also partnered with suppliers of headend equipment and set-top boxes, including Divicom, Samsung, and Panasonic.
Incase you don't know, CableLabs is a research and development consortium of cable television system operators representing the continents of North America and South America. CableLabs plans and funds research and development projects that will help cable companies take advantage of future opportunities and meet future challenges in the cable television industry. It also transfers relevant technologies to member companies and to the industry. In addition, CableLabs acts as a clearinghouse to provide information on current and prospective technological developments that are of interest to the cable industry.
CableLabs maintains web sites at www.cablelabs.com; www.cablemodem.com; www.cablenet.org; www.opencable.com; and www.packetcable.com.
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Subj: What will it take?
By: Jim Mendrala and Larry Bloomfield
I'm not sure if the vendors don't understand the exigencies of electronic cinema or they are too willing to compromise. One thing for sure, they've got to stop listening to the scuttlebutt. Permit me to explain. There is as much difference between electronic cinema and high definition television as there is between analog-NTSC television and digital high definition television and perhaps even more. The standards and specifications that applied to analog television just didn't work for digital and high definition television. A whole new set of standards had to be developed to accommodate the newer HDTV technology.
By the same token, there is no way that electronic cinema can achieve the level of quality required using the standards and specifications that apply to digital high definition television. Pundits in the emerging electronic cinema industry must establish criteria, specifications and standards applicable to the new needs of this very different media. The three primary concerns are in the areas of screen brightness, colorimetry and required resolution. Don't think for one minute that these are the only concerns. We will address each of these three issues and others in future editions.
There are many similarities, but there is also much dissimilarity. The larger high definition television displays are normally in the 70-100 inch range, diagonally. In contrast, movie theaters typically have 20 feet and more in height by whatever aspect ratio. Keep in mind that this is nearly the height of a two-story building. Even the slightest anomaly in the HDTV presentation, that would probably go unnoticed in the wonderful world of television world, would be highly objectionable on the larger screens in an electronic cinema theater.
The creative forces and genius behind the entertainment industry will nearly always shoot a presentation much differently for presentation on a television screen than they will if the target presentation media is the motion picture screen. The quest for improved quality has seen the movie industry evolve from small frame formats to 70-mm. The number of photosensitive particles on a piece of film is limited. In poorer types of film it appears as grain. There is also a physical limit to how far the chemistry of film will permit the variety and gradation of colors. An all-electronic system does not have these same photochemical limits. The eye plays tricks on us and both television and film take advantage of these physical peculiarities.
Since the most common type of film used today is 35-mm, that will be my reference point, but electronic cinema engineers never loose sight of the fact that some material is done in 70 mm and it's quality must be accommodated in the standards as they are evolved. There are a finite number of pixels that will resolve 35-mm film where by the media doing the resolving becomes transparent. High definition television rounds out at about 2 million pixels per frame. Electronic cinema will begin with approximately 8 million pixels per frame.
It is blatantly obvious that electronic cinema should and will take advantage of the ever evolving world of digital where ever possible. With that in mind, most people who are familiar with digital video are aware that it is a memory and bandwidth hog and that's being kind. Compression is an absolute must, but the current techniques and technology are not satisfactory and do not lend themselves to the quality required in electronic cinema. Work is on going at such places as Sarnoff Research and other laboratories in an effort to develop a compression system that will accommodate the larger number of pixels per frame without introducing unwanted artifacts and anomalies. Compromise is not an option.
It seems that the current thinking at the several projection companies we have been dealing with is very myopic in nature. At the risk of raising a pun, they do not see the big picture of electronic cinema as a market in the near future. We are developing a need. If the current projector companies can't fill that need, trust me, someone will step up to bat and do the job.
In future issues of the Tech Notes, we will also address the totally electronic cinema system that includes everything; cameras, post-production, storage, distribution and display.
We haven't even acquired the microphone, much less put it out for the "fat lady." Stay tuned for more as we share with you the evolution of this embryonic and vital industry.
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From: Nicholas Bodley >>> nbodley@tiac.net <<<
About your story: Performance Comparison of ATSC 8-VSB and DVB-T COFDM Transmission
Systems for Digital Television Terrestrial BroadcastingBy: Dr. Yiyan Wu - Communications Research Centre Canada
I'm sure I'm not the only one who thought this item (below) left off rather suddenly; no URL for a follow-up, either. Nevertheless, it's good to see a list of good things about 8VSB, and also, enjoyed the rest of the newsletter.
Regards, Nicholas Bodley******
Subj: An answer to above.
By: Larry Bloomfield
Nicolas, we agree. There was no URL in the material that we received that would have lead anyone back to Dr. Yiyan Wu. This is why his snail mail address was included, which we normally don 't include.
Although I would like to see a mobile friendly modulation system in place, it wasn't dummies or idiots that decide upon 8VSB, these are well educated and well grounded engineers who, I believe thought they were doing the right thing. Perhaps if the developers of digital television had a little more time to ensure they had made the correct decisions instead of being pressured by a bunch of money grubbing politicians who were blinded by all the money they could raise from the auction of spectrum, thing might be different. Well they're not and we've got to either fix it or replace it before more good money changes hands. What we've got as a digital television system doesn't work in a practical day-to-day sense as the average television viewer is accustomed to. Then I'm probably preaching to the choir.
You know there's a lot to be said for the caliber of receivers available. In a word, they stink. I could fill pages justifying that comment. It is, however, anticipated that 2nd, 3rd, etc generation 8VSB receivers will perform much better. NAB has made this point and so do many that are familiar with today's receiver design. The question is, can the implementation of digital television afford the delays while the receiver manufacturers catch up? Here's another instance where a politically rather than a technically motivated FCC truly blew it. Why couldn't these very well educated engineers, when they were setting transmission standards also set receiver standards as well? But then with their current philosophy of how to do business, what could we expect? And BTW: The only significant step in tuner design improvement in the past several years has come from Microtune. LB
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Subj: A couple of questions
By: Larry Bloomfield
Both of my questions can and should be answered by one or more of our readers. Although totally unrelated, I believe they have substance and I'm sure that more than one of you has given at least passing thought to the subject matter. I have seen the first issue addressed in other Internet forums I subscribe to. The second area addresses some residual professional pride from the days with one of my former employers.
The first is in the area of the digital domain. Hardly a week goes by when we hear of some virus or another affecting the Internet or some program that has been infected. Hard drives are allegedly erased. Programs destroyed and computers (I would assume the CPU) rendered useless. With the migration to digital, what is to prevent some twisted mind basement savant from coming up with a virus that would do something similar to set top boxes (STB) or other areas of the digital television plant? If this is true, what measures is the industry taking to prevent such a thing from happening? I don't have the answers and would entertain publishing any reasonable addresses from our readers to these questions.
Several years ago, I had the distinction of being an employee of CBS at there locally owned and operated station in Los Angeles, the then KNXT now KCBS-TV. I pulled more than one shift in Central Control (CC), Master Control elsewhere. As CC supervisor, we were responsible for the technical quality of all program material that left our studios on its way to the mass of viewers. To the number, each and every one of us was proud of the quality CBS put into their product.
Until several months ago, that quality was passed on via the direct broadcast satellite services. Although the material was, and is, NTSC, it was then, as it is now, delivered to the viewer's IRD, digitally. The quality was literally the same as that delivered to any of the several hundred affiliate stations in the CBS network. The West Coast CBS programming was from KPIX in San Francisco.
Some boy wonder, not satisfied with the status quo, decided to change things and over night the quality went to hell in a hand basket. Although the East Coast feed was switched at the same time, I saw no appreciable loss in quality. I speak only of the CBS West Coast DTH feed from KCBS-TV.
On any given night, viewers can experience any manor of picture distortion and or interference: Everything from radio frequency interference to fading. A person, who obviously does not know that you don't screw around with the picture during commercials, keeps punching on and off some form of logo in the lower left-hand portion of the picture that resembles a distorted postage cancellation mark. The insertion of this "bug" is so poorly executed that it causes massive phase shift in the picture content.
As a former CBS employee, I still have some residual pride in the work done at 6121 Sunset Blvd (Columbia Square - KCBS-TV). I truly hate to see my former fellow workers required living with this gross embarrassment and complete lack of professionalism. I hope someone can address the issue and tell us why and when the matter will be corrected.
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Subj: More Extracts from HDTV Report -- By When Expect to be Doing Local Productions From: Des Chaskelson, Research Director, SCRI International >>> des_chas@scri.com <<<
It appears from our survey that stations are a bit leery of plunking large sums of money down on an unknown and as yet unproven track record where digital television is concerned. This seems be especially true in the area of High Definition. It is a safe bet that as equipment is replaced, it will be replaced with digital gear, but the question of high definition does not seem to be the case until the year 2003 and after.
At most stations, news equipment and production equipment is not normally shared. News equipment tends to get the greatest field abuse and would therefore probably be replaced sooner. On the other hand, the field production equipment used by the Creative Services folks can fill the bill and be moved into the vacancies created from time to time in local news/sport. With an eye to making the newer production technology available to clients, this is where the smart money says the newer, equipment with possible HD and SD capability equipment, would start out in a station.
In addition to the new technology, different production techniques must be employed with the wider screen 16X9 aspect ration than most crews are accustomed to for the end product to look good. The numbers from this year through to and including 2002 in all area of television production appear to be in a holding pattern.
As the networks take the lead and the stations have the opportunity to see the production techniques that work well and prove that the new technology is not another folly, things will grow very slow as the numbers indicate. This is especially true of High Definition television. The numbers seem to show that standard definition is more of a safe choice than anything else is.
Most stations have at least one studio where most everything comes from. News occupies a wall or corner. With the new, computer created, virtual sets, even more can be expected from the same studio area. Since the studio doesn't get the abuse the field equipment gets, the chances of it being replaced as often are less likely. Because of this, Local Variety, Public Service, News production, Special Events, Variety programming, Pre-recorded shows, etc. seem all to be in a wait and see mode as well. Like in the early days of color, when the public tunes in and wants the bells and whistles that go with digital television, broadcasters will jump in with both feed and wonder why there is a shortage of equipment. Again, anywhere from a third to one half of the broadcasters responding to the survey just don't know.Des
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The Tech Notes are published for broadcast professionals, and others, who are interested in Electronic Cinema, DTV, 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. 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.
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