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  Some of the information may be out of date.
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Tech-Notes
Published by: Larry Bloomfield & Jim Mendrala
E-mail = hdtvguy@garlic.com or J.Mendrala@ieee.org
June 23, 2000
Tech Note - 058
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This issue of Tech-Notes is also posted on our website. Past issues prior to Tech-Note #050 are available at: http://www.SCRI.com or http://www.HDPictures.com

WE ARE IN THE PROCESS OF BUILDING OUR WEB PAGE!  What an experience!  Any help, suggestions, etc. are both needed and appreciated. http://www.Tech-Notes.net

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Your assistance in getting Klaus Landsberg recognized by the industry’s various organizations for his highly significant engineering and technical contributions to the television industry are appreciated. Anyone having information, pictures, stories etc., please contact us. 

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Reader comments: 
From: John A. Luff, Synergistic Technologies, Inc.
e-mail: jluff@STIDigital.com 

(EdNote: Mr. Luff is a Member of ATSC; a Sustaining Member of SMPTE and an Associate Member of NAB.

Michael Brinkman left us with a question about the derivation of "EDTV" and "ATV". EDTV refers to the Japanese satellite delivery system, which was in fact intended to be 480p/60. The production environment for this was built around two interconnection standards (both are part of SMPTE 294); one uses a dual link SMPTE 259 interface with 4:2:2 coding for a total bit rate of 540 Mb/sec. (Section 4 of the SMPTE 294); the other uses the 360Mb mode of SMPTE 259M (Section 5 of SMPTE 294) to transmit a 4:2:0 version of the recorded signal (obviously with a quality hit). EDTV uses 13.5 MHz sampling. I am not clear on whether EDTV ever made it on the air in Japan. 

18 MHz sampling never caught on, perhaps for the same reasons numerated in Michael's response (i.e. less sensitivity to H resolution). It should also be noted that 16:9 pixels with 720x480 mapping are not square (858 pixels or so would be required; the actual pixel aspect ratio is about .84:1)...which is trivial only on the home display. 4:3 pixels we commonly use are not square either (actually 1.12:1 aspect ratio pixels). 640x480 gives square pixels; hence the computer standard uses this mapping. 

ADTV was a system proposed by some US broadcasters that used two 6 MHz. analog channels to broadcast higher resolution pictures in a compatible manner. It never moved beyond the demonstration level. 

ATV (Advanced TV) was one of the earlier names for our current DTV. It was a "soft" term to connote HDTV without emotion, but also to include the lower resolution modes like 480i and 480p, as well as multiplexing. If you look back in Merrill Weiss's book, "Issues in Advanced Television Technology", the definition which we started the current movement from was indeed ATV (see page 4). Indeed in Merrill's extensive index (1996 publication) DTV is not referenced. 

I strongly concur with Michael's characterization of 480p as it relates to 480i and NTSC. Been there, done that. The largest differences in DTV are the component nature and the progressive scan modes. Anyone should be able to make exceptional pictures with a dense pixel map and sufficient frame rate.  The magic of 720p and 480p is the appropriateness of the decisions made in defining a technology that matches the human visual system and the consumer entertainment distribution system of today and tomorrow. 

John A. Luff

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From: John A. Luff, Synergistic Technologies, Inc. 

Mr. Manfredo is mistaken in one respect in his statements about 480p, and Mr. Mendrala's response is also misleading. 480p is not "1/2 D-1". The sampling grid for 480p is generally assumed to mean 704x480P. In the vertical direction it is double the resolution of NTSC, and due to the component nature of DTV transmission it is considerably better than any current analog consumer appliance can produce. 

Mr. Mendrala is combining references to 480p (common usage) with VGA when he states that 480p is 640x480. Common usage for 480p in the entertainment world connotes 704x480. That is one of the sampling grids in Table 3, but so is 704x480P (as well as 480i). Both standards are in Table 3, both could be used, but in a practical sense no one is using the square pixel variation since no video devices product content with this sample grid. A careful review of Table 3 will show that both are show with interlace and progressive variations. Also important to note is that the 704 H pixel-count does not match ITU-R BT601 (which is 720 pixels with 704 "active" to account for filter templates). ATSC and MPEG are considering what to do about this issue. It is very important to program producers since the change from 720 to 704 affects aspect ratio and other important issues. 

John A. Luff

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Subject: The Wonders of PSIP 
From: Lee Wood lwood@easystreet.com

(Ed Note Lee Wood is the Director of Engineering at KOIN-TV in Portland, Oregon. His comments and opinions here are his own and do not necessarily reflect those of his employer or anyone else.) 

To help understand the Program and System Information Protocol for Terrestrial Broadcast and Cable, or PSIP, for short, permit me to make a few comments. 

All encoders come with the ability to generate at least a basic PSIP stream correctly.  It is up to the station to take the time to set it up correctly.  Most problems are the fault of individual stations NOT the system.  In my market everyone has similar PSIP capability, but only my station (truthfully, me) has made the effort to 'get it right'.  We are the only station to map our analog service.  Only one other station correctly maps the major channel (and they started that only recently).  Only two of us correctly map our 'simulcast' to the recommended x-1 minor channel (others use x-2 or x-3).  One station does not even put their call letters in as the short channel name - it's blank.  Soon we will add expanded program guide capability (I don't know if the others plan to anytime soon).  Like anything else with DTV is does take some effort to get it right, but not THAT much effort. 

The PBS 'issue' is because they distribute an ATSC stream via satellite so stations do not even need an encoder to get on the air.  DTV tuners find it just fine as 80-x.  They have two services.  One is a four program multicast of children's programming (80-1 through 80-4).  The other is an HD demo/program service identified at 80-1 with mapping for 80-2 through 80-4 present as a pre-announce so tuners will always be able to find the four services as stations switch back and forth between the two feeds.  They chose channel 80 because it was available nationally since there is not an RF channel 80 (anymore).  (The national PBS feed on DirecTV is also mapped to channel 80.)  It works very well for startup local PBS stations until they can 'grow' into the full service requirement in 2003. 

As for the major-minor channel scheme, personally I like it.  It allows us to extend our 'brand' by relating new services directly to it. 
Channel surfing makes it transparent, but our '6' brand is always there. 

Lee Wood

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Subject: Industry Leader, Radio Shack, Speaks out on HDTV.
By Larry Bloomfield 

While surfing the web for possible stories, I ran across something that seemed rather far-fetched, at first.  From the Radio Shack Web site: 

"You don't have to buy a new TV to experience the richness of HDTV. You may just need an HDTV receiver that allows you to view the superior quality of programming on your current television set. Then you can discover the world of clear digital broadcasting." 

It is my understanding that all this ballyhoo about format is just that!  It really doesn’t make a hill of beans difference what the station is transmitting, 1080i, 720p or 480i/p (for progressive or interlace).  The issue is that the receiver will most likely convert the incoming signal into whatever format it is designed to display and that’s what you’ll watch! 

In discussing this with an associate, C. B. Patel, he said:  “It is not Double Talk. It is not too far from the truth.  By richness, I believe it implies noise, ghost free picture.  And YES, if you see noise free and ghost-free picture, it would be better than the NTSC picture in the studio.  If you have a late model television set, I am sure it has an S-video input. It might have R, G, B, or Y, Pr, Pb inputs. 

“An HDTV (set top box) STB would have S-video, Composite video, and RGB outputs.  However, the RGB output if for most probably HDTV (16x9) monitor.  The S-video is for NTSC. You will need a special connector-cable.  So YES, you would immensely enjoy HDTV transmitted video simply because it has none of the NTSC artifacts akin to analog signal reception. 

“Double talk? May be; but lot of truth in it also.” 

(Ed Note Mr. Patel is a 20+-year veteran with Sarnoff Labs.  He is currently a consultant to Samsung the TV manufacturer.)

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Subject: In Home Repeater (aka: personal Single Frequency Networks) 
From: "SWL" (Initials used at authors request.

Attended the DC SMPTE Chapter meeting where Michael Simon, Rohde 
& Schwarz, Inc., presented a nice briefing on an "Introduction to Digital Terrestrial Television Broadcast using DVB-T COFDM Fundamentals."  This was not an ATSC vs. COFDM affair, just a simple tutorial of how COFDM works presented to DC area SMPTE members. 

In his briefing, Michael presented at least one astonishing (at least to me) COFDM capability that I have never heard anyone discuss.  We have all heard about COFDM's ability to do Single Frequency Networks, where broadcasters could provide gap-filling
services in communities’ significant terrain masking concerns.  What Michael talked about was a different great idea – single frequency networks in your HOME.  His thought was that you could install a good rooftop TV that enabled guaranteed reception, then attach a very low power broadband RF repeater in your attic, which would enable every TV in your house to use its portable antenna (small, etc.) without antenna wires. 

In concept, this is truly just another application of SFNs, albeit in a micro-size cell structure (a single home).  When I heard this, I thought, finally, this explains what DVB-T was trying to do on the first day of NAB2000 with their micro-repeater.  They were not "cheating" as certain ATSC bigots claimed on this very list; they were demonstrating a technical
capability of COFDM SFN systems, with direct applicability to millions of consumers.  Now for the record, DVB-T removed their repeater after the first day of NAB, and COFDM reception worked just fine in the show hall without the repeater (but not so for ATSC as I recall). 

The only gotcha with this micro-SFN as I can see it is the "repeating" of the existing analog signals as well - the echoes caused by your internal micro-cell would kill your NTSC and ATSC (and FM and ...) reception, so we would have to wait for the "digital
transition" to be nearly complete to effectively use this capability. 

The other conclusion I drew from the briefing was one I have thought before.  DVB-T is an elegant TOOLKIT of capabilities. Broadcasters could change modes (2K/8K), provide different robustness levels (fewer, more robust bits in drive time, more bits that are less robust during prime time), provide hierarchical coding (HDTV and mobile in the same transport), and on and on.  Contrast DVB-T's flexibility with monolithic implementations of ATSC 8VSB - every station in every topographical region has to do the same thing all day long.  What a failure of vision. My opinions are my own. 

SWL
(More on the same subject) 
From:  Andrew Oliphant, Coordinator, VALIDATE, 1995-98 and part of the BBC. andrew.oliphant@rd.bbc.co.uk

Televes developed the prototype in-home repeaters.  This work was done in the collaborative project VALIDATE (1995-1998), sponsored by the European Commission, which set out to verify in detail the DVB-T specification.  The prototype in-home repeaters were tested by several VALIDATE partners, including the BBC.  Some of the results were given in a paper at IBC 1998 'VALIDATE and MOTIVATE: Collaborative R&D to speed up the launch of digital terrestrial TV' (downloadable from  http://www.bbc.co.uk/rd/pubs/papers/), and more information is available in VALIDATE's Final Report (downloadable from http://www.bbc.co.uk/validate/). 

In the BBC tests, the repeater gave portable reception in all rooms of the five dwellings tested, none of which had perfect portable reception without the repeater and some of which were in areas of low field strength where portable reception would otherwise have been impossible.  There were no problems of stability when the repeater was fed from a rooftop antenna, but some care was needed when a receiving antenna within the roof space of the house was used. 

The prototypes made by Televes in VALIDATE incorporated filtering so that in principle they retransmitted only the digital channels (the tuning was factory-set for the channels required).  However, they were made using techniques appropriate for mass production for the domestic market, so the filtering could not greatly attenuate the adjacent channels.  As digital TV is commonly transmitted in channels adjacent to analogue TV, a quick check on the effect on portable analogue reception of re-radiating the adjacent analogue channel was performed and found it was not as important as might have been expected.  Andrew Oliphant

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Subj:  Some have it; others don’t! 
By:  Larry Bloomfield 

Here’s some interesting facts received from several sources that are attribute to David Elliot, who has known affiliations with the ATSC Task Force on RF System Performance and ad hoc groups: 

The number of households with/without cable responding to a question that was raised in one of ATSC’s Ad Hoc Group on Field Test Measurement and Methodology meetings reports that the current number of households (HH) receiving television is 100,800,000. 

The current number of HH connected to cable is 71,545,000.  The current number of HH connected to cable or an alternative provider (satellite, MMDS, etc) is 80,346,000. Further defining the 100,800,000 households, 34% have 2 TV sets. Of those 100,800,000 households, 40% have more than 3 TV sets. 

The report continued:  It is difficult to approximate how many TV sets in households served by cable, or others, are actually receiving over-the-air, since people do not always report additional sets tied to their cable system. However, it has been assumed that, in multiple set households, at least some of the sets are capable of over-the-air reception, whether or not they are also connected to cable. 

What is really interesting is not so much “the figures” above, but what followed them in the message.  It seems that the ATSC considers all of its deliberations and plotting to be on par with the national defense and should not be let public until the battle is all over.  I have no doubt that the individual members of these “teams” or Ad Hoc groups are sincere, honest, upright citizens, but remember who they are serving and we’ve been led down the primrose DTV path by them before and look where it has gotten us! 

It is quite understandable when a company or manufacturer, not a standards setting body, wishes to keep confidential or secret their “goings on,”  but this does not hold true for any group that is setting “standards” that will affect every one involved in the television chain in the future.  The chain I speak of is everything from acquisition to presentation.  Set the standards, then let the companies and manufacturers go off in their cloistered laboratories and come up with all kinds of new and wonderful ways of implementing these standards. 

Here’s the jest of what I’m referring to: “The reflector (electronic communications via the internet) will be used to provide a forum for discussion among members of the ATSC Task Force on RF System Performance and ad hoc groups. In addition, the reflector will be used to distribute documents including meeting notices and agendas, minutes and discussion papers. Access to this reflector is limited to the members of the ATSC Task Force on RF System Performance, ad hoc groups and ATSC staff. While we understand that you may occasionally have a need to share information posted on this reflector with others within your organization, please refrain from forwarding emails from this reflector to others outside of your organization.”  This is reminiscent of the WWII slogan: “Loose lips sink ships!” 

When contacting the ATSC about this balderdash, I was told that they had nothing to say, but yes they did.  When pressed, I was told that the press would get things all distorted and wrong; like they never have.  I was told the press was not welcomed to any of their deliberations; only engineers who have a stake in the business. 

I offered my resume and telephone numbers to the General Managers where I’ve serve as Chief Engineer, but that didn’t seem to impress them.  I even mention a fine associate in both the engineering areas and published regularly, Mark Schubin.  I was told that, if he or I attended any of their meetings, we had to subscribe to their rules or we couldn’t attend.  I said that this is not the invasion of Normandy!  We simply need a plan to get from point A to point B and that’s no secret! 

One would think that after the massive crises the transition to digital television is going through, ATSC and the rest of the alphabet soup in Washington, DC would welcome as much help, from as many sectors, as would have the temerity, after all that has happened to date, to step up and offer it! 

It is not difficult to believe that ATSC stands for Annihilate Terrestrial Service Completely. That may not be their charter, but you sure could fool a lot of folks out there who’ve spend tons of money trying to make what they gave them work! 

If you really want an eye-opener, check out the comments filed with the FCC as part of their review of digital television.  (www.fcc.gov) If that doesn’t get the home fires burning, wait until next month when Congressman Tauzin (R-Louisiana) and his band of mighty congressmen see, first hand, what alternative means of transmission can do for the viewers across this fair country of ours.  As Al Jolson said: “Wait a minute! Wait a minute! You ain't heard nothin' yet. Wait a minute, I tell ya, you ain't heard nothin'!” 


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Subject: About Convergence 
From: C. Gould Program Director, City Internet Radio 

I'm not making any predictions on what the internet will do to existing media, but commenting on the predictions of others made over the past couple years.  This is sort of a paraphrased version of conversations I've had with friends speaking on the Internet, and it's impact on traditional media. 

My soapbox was slowly being built as I read more and more predictions, and was rapidly completed when I read how the Internet will "Kill" TV and radio. 

Where have I heard arguments like this before? 

When TV came out, everyone was so-sure that radio was finished.  When Cable came onto the scene, everyone was so-sure that it was the death of Broadcast TV.  Now the Internet is here, and everyone is so-sure that it will kill either Radio or TV (If not both), and Newspapers are next. 

How stupid!  The Internet is so much more than any of the other media revolutions that came before it...but it is its own media.  Right now, we are ALL still trying to figure out just what to do exactly with the new tools handed to us.  It is like we were handed a new set of radio frequencies and a clean slate to start all over again.  At this stage, all we can think of is re-creating what we already know, i.e. Radio, TV, Newspapers. 

The problem is this: 

The Internet is *not* Radio. 

The Internet is *not* TV. 

The Internet is *not* a newspaper. 

And the Internet is *not* a magazine. 

Radio is Radio, TV is TV, Newspapers are newspapers, etc. 

The Internet, yes, can imitate all of the above for the most part, if we want it to, but it is silly to limit its potential to what we already know.  The Internet is a brave new world.   In the long term, I see the Internet as being something totally different than the other mediums, and it will be no more of a threat to existing media as TV was to Radio, no more of a threat than Cable is to Broadcast TV, and no more of a threat than any of the other two mediums are to Newspapers (and vice-versa). 

The internet will, no doubt, force a change in the way the other Media operate in as much as each media has done to each other over the years, but it will *not* kill other forms of media. 

I see the Internet changing the world society in general, and it changing how we view entertainment and news as it develops.  Is this going to be a good thing? I don't know. 

I will place a bet on this: None of us know right now what the Internet will be. 

Using past history as a model: 

This is like the beginnings of radio communications.  Just sending Morse code to summons help from a ship in distress was the only practical use anyone really had of radio until people were able to speak over these radio waves.  Then, everybody and their brother had a radio station (back when there was only one frequency) transmitting anything from the word of God to the latest elixir you can buy, courtesy of the broadcast station in your local drug store. 

No one envisioned that radio would be what it is today with all the music formats, talk shows, etc. 

Almost NO ONE  (except some clever scientists) envisioned sending pictures over these radio waves to create TV.    Why? Because in the early 1900's, using the radio wave for mass communications was a new thing, and had a sense of novelty about it too.  Inventors were working on sending moving pictures over these new-fangled radio waves not to make money, but t see if it could be done. 

When it was proven that it could be done, what did the programmers of that day do?  They imitated what they knew at that time.  Just as some early radio stations did their best imitations of the Newspaper, by reading the paper on-air live, Early TV Imitated Radio at that time (with TV Versions of Radio dramas).  This eventually forced radio to find new ways of entertaining. 

The change in TV right now is quite interesting in that it is now mirroring radio again.  With so many channels to choose from, TV has now moved to doing "formats".  The Sci-Fi channel, Learning Channel, the Gardening Channel, etc.  This is TV's reaction to Cable and the fact that there are 200 channels for people to choose from. 

Who would have predicted that just 15 years ago? 

Point is: Let's start looking forward.  What *new* things can we do with this new exciting medium, and lets stop making absurd predictions of the Internet squashing Radio, TV, and Newspapers.  It will, in the end, stand side by side with the older media, and will most likely be something just as unique, exciting, and as useful as the other media is to each other and to us. 

I'm not claiming to be some prophet.  I don't know the ultimate answer to this either, and would admit that our Internet project is currently more-or-less an imitation of traditional radio, but we are always working hard on what *more* can we do as we grow that doesn't involve imitating traditional media. 

What can *we* do as a medium that the other mediums cannot do?  This, I think, would be the basis of some useful discussion, don't you think? 

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(On the same subject, but a different person): This is SO critical for people to understand and it breaks down into subcategories too. Film is also not TV; radio is not records, etc. The illusion that creates an entertaining experience is extremely fragile and requires totally unique priorities for every specific medium. 

In the end, it has always been material produced for the specific medium involved that became successful because the different media have never really been interchangeable no matter how badly the marketing people and the stock market have wanted them to be. 

Bob Olhsson,  Audio Mastery

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Parting Shots & Food for thought:

1. Most television engineers are damn good at what they do; keeping the television system going as flawlessly as possible.  Then why do other parts of this industry think it is the engineer’s job to come up with business plans and generate programming when it comes to digital television?  Isn’t it time for the other non-technical types to start earning their pay and do their jobs? 

2. We are entertaining the idea of a sponsor, but have not decided on that as yet.  Make us an offer we can’t refuse. 

3. With all the news recently about viruses etc, is there anyway these could impact a Digital television station’s bit stream? 

4. Jim Mendrala is preparing a report on InfoCom and will be in our next Tech-Notes, which will be out shortly. 

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The Tech-Notes are published by Larry Bloomfield and Jim Mendrala. We can be reached by either e-mail (above) or land lines (408) 778-3412, (661) 294-1049 or fax at (419) 710-1913 or (419) 793-8340. The opinions expressed herein are those of the individual authors and do not necessarily reflect the opinions or positions of their friends, employers or associates.  If you wish to remove yourself from this list, send an E-mail to: hdtvguy@garlic.com.  In the subject area put the word Remove.  Please visit our web page to review our policies and to see any additional information. http://www.Tech-Notes.net.
Thanks.

 
 

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