Archived Tech-Notes
Published by: Larry Bloomfield & Jim Mendrala The following are our current e-mail addresses:
E-mail = hdtvguy@garlic.comor 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 Some of the information may be out of date.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 15, 1997
Happy Fathers' DayNWTN - 004
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---------------------------------------------------------------------------For the first several issues I have been advised to print our mission statement so no one will have any question why we are doing this.
We feel that there is a need to have an electronic listening post, clearing house or informal source for what's happening in this rapidly developing world of DTV, ATV, ATSC and HDTV, etc., etc., etc. 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: DTV, HDTV, and Microwave Equipment
From: Peter Finch
The future requirement to transmit NTSC and DTV/HDTV simultaneously has many stations planning and pondering.
The microwave radio part of the planning should not be a problem. MRC is already selling the DAR series of microwave radios which are totally compatible with analog or digital traffic. In fact, almost every quote that goes out of this office now is for DAR radios and not for conventional baseband radios.
DAR radios, like their heterodyne FLH counterparts, are looking for a 70 MHz input or output. To use these radios in the analog mode, FMT and FMR cards are inserted to bring the analog baseband to 70 MHz. In the digital mode, the DAR radios will be fed from a digital modulator or to a digital demodulator.
The key is that DAR radios are compatible with both present and future station requirements.
Companies, such as Leitch, are working on digital multiplexers which will accept NTSC and DTV/HDTV inputs and combine them into a single bit stream. It is this stream that will feed the digital modulator. Northwest Communications expects to be able to offer the Leitch unit after final design in about August of this year.
While planning microwave antenna systems, plan to use low VSWR antennas to minimize data errors. For the same reason, angle or space diversity may be beneficial.
If you have any on-going questions, we are all learning together so please feel free to call.
(Ed Note: Peter Finch represents a number of companies that deal in RF equipment He is home based in Portland, OR)
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Subj: News Things
From: Dave Hill
There were some questions from the AFCCE engineers regarding the DTV allocations. It was found that in congested areas, some of the assignments were based on directional antennas. A paper by Obed Bendov at Dielectric, "Understanding the Requirements for DTV Construction Permit Applications" is listed on the "afcce.org" Internet home page and makes for interesting reading. Also, remind one and all that the question is not one of transmitters at this point in the game but one of towers and antennas. They are the long lead items.
(Ed Note: Dave Hill represents LDL LeBlanc, Larcan, TTC and other members of that particular family of companies. He is home based in San Mateo, CA)
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Subj: A progressive scan 3-CCD minicam at ShobizExpo, Los Angeles Convention Center.
By: Jim Mendrala
Sony has a mini color CCD camera that progressively scans the image captured in -1/60 of a second or less, and outputs an interlaced NTSC video signal. The camera is also available in PAL with 1/50 of a second or less capture. The advantage is that if one uses a still frame or slowmo that image is a lot sharper than a traditional interlaced camera with its 1/30 second capture. The camera uses 3 CCD chips and has a horizontal resolution of more than 700 lines.
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Subj: "DT Views" The following are excerpts from the Harris Corp. edited by the NWTN staff for brevity. Feel free to contact Harris Corp for more details.
Harris Corp and PBS have announced that they will launch a major nation-wide educational initiative dealing with DTV. The joint effort is called "The DTV Express: "Destination Digital!" and will be a two year, fifty location road show. The training will cover technical, managerial, financial, legal and regulatory aspects of implementing DTV. We will keep you apprised here in the NWTN when and where as we find out.
Harris Corp. announces that they have entered into three major agreements to provide analog and digital television (DTV) transmitter equipment with CBS for their 14 O&Os, with Silver King Broadcasting for 12 of their station and with Post-Newsweek for 6 of their stations. Last July 23, CBS affiliate WRAL became the nation's first commercial high-defination television station. In April of this year, WCBS became the "Big Apples' first Hi-Def station. Harris provided transmitter equipment for both of these stations.
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Subj: Tech notes
By: Larry Bloomfield
I'm sure we are all looking with great interest at these new Hi-Def stations as they go on air with their state of the art equipment. I have no doubt that we will all make mistakes, set mile stones and most important, learn from each other as more and more of us embark onto these uncharted waters.
Lets suppose that anyone of us had our new Digital transmitter in place, tested and working on our new frequency, feeding our new Antenna. Everything is up and working fine! The one burning question that comes to mind is now what do we, or these other early entries into this new DTV arena, broadcast? Test patterns (shades of the old Indian head monoscope) or the ever-familiar color bars?
To the best of my knowledge there isn't any Hi-Def programming available at this time. What aspect ration are they broadcasting, the old 4 X 3 or the new 16 X 9? If all we are doing is simply bumping NTSC up to the the new format, how can we call this Hi-Def? I believe the rhetorical question is: "Don't we have to originate in Hi-Def and scale down to the poorer quality NTSC until it goes away for good?" Enhanced garbage is still garbage!
I'm not trying to be antagonistic to the issues at hand, but this is all so reminiscent of the stories Harry Lubkee told me about his adventures as Chief Engineer at W6XAO (The first TV station in Los Angeles and west of the Hudson river, which went on the air in December of 1932). Harry had many, many years of test pattern logged before even the first few hours of programming became regular fair on the kinescopes in the city of Angeles. It took nearly fifteen years, not to mention a world war, to get receivers into the hands of the general public. I believe we are looking at 1998 for Hi-Def TV receivers to be readily available.
My point to all this is, we are, or need to be, Harry Lubke's and use this time to learn, develop and come up with the best possible way to get great pictures and superb sound, using every ounce of available technology. Those great pioneers like Harry Lubkee and Klaus Landsburg, though competitors, shared their experiences through those long bleak years and in doing so, set most all the technical mile stones in our industry. They even formed the very first television engineering organization, the Society of Television Engineers (STE) well over 50 years ago (and it's still around down in LA) as an arena for this sharing process. Let's put aside any political bias and help each other to become the best we can be.
And finally, this is why we will take the time here in the NWTNs to explore Hi-Def studio equipment as well as the boxes "up on the the hill" and their associated "sticks." Your input and comments are most welcomed.
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Subj: Flat Panel Plasma Display
By: Jim Mendrala
Here at last! Well at least in Europe. After years of waiting for the large flat screen displays to appear you can now actually go out and buy one. The Fujitsu 42 inch color plasma display has made its domestic debut in "flat TVs" from both Philips and Grundig.
Philips chose the new 42 inch color plasma display by Fujitsu Microelectronics for its Flat TV receiver. This is the first in a series of large wide screen receivers from Philips. Phillips intends to bring a new dimension to home television viewing. The Philips flat screen TV delivers high contrast images together with with an ultra flat body.
The Fujitsu display is the worlds first color plasma display. It utilizes an advanced color plasma technology which is ideally suited for use in domestic television receivers and promises to release the concept of a wall hanging TV.
The new 42 inch diagonal screen provides an effective display area of 37 inches (920mm) by 20 inches (518mm) with an aspect ratio of 16:9. The thickness of the panel is about 3 inches (75mm) and weights about 39 lbs. (18kg). Bright screen images can be viewed at angles up to 160 degrees. The panel can display 167 million colors with a peak white brightness of 87 Foot-lamberts (300 candela/sq meter) and a contrast ratio of greater than 70:1. The 852x480 pixel display is progressively scanned (non-interlaced) and is flicker free.
It is estimated that by the year 2000, large wide screen TVs will account for one third of the total television market and plasma displays for 10% of that market, or 303 million sets annually. Fujitsu Plasma Displays are already in use at airports, stock exchanges, and other locations worldwide.
The Grundig "Planatron" also uses the Fujitsu 42 inch Plasma Display. It can be wall-hung or rack mounted. The rack mounted version incorporates the TV receiver in the rack itself. This holds the power supply, receiver, signal processor and display controls as well as all necessary interfaces. Extra functions include Dolby Surround Sound with Prologic and the ability to connect external speakers.
Sony says it will have an HDTV receiver using the 42 inch diagonal Plasma Display from Fujitsu available here in the US around the last quarter of 1998. It will have a starting list price of $2,500 but that price is expected to drop rapidly as sales increase.
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Subj: Microwave Links for DTV/HDTV
From: Peter Finch
As I get pieces of information regarding the use of microwave links for DTV/HDTV, I will pass them on to you. My news may or may not be new to you! If you have any questions, please feel free to feed them back to me and I will do my best to answer them in this mutual learning process.
Q: Why is it that a microwave DTV link may not be able to cover the same distance that is possible on an analog link when it is possible to send digital TV data to a satellite thousands of miles away?
A: The dense part of the atmosphere is very thin indeed. The vast majority of the path to and from a satellite is through either the vacuum of space or very thin atmosphere. A terrestrial link has to pass entirely through the dense gases we breath. The adorations caused in this layer can result in data errors. These errors can be minimized by careful path analysis and by using antenna diversity and low VSWR components.
For DTV, microwave antennas should be the "low VSWR" designs and, if possible, use swept waveguide/connector runs. There would seem to be some limitations here as sweeping a waveguide system on-site requires quite expensive test equipment. It is perfectly possible to buy the waveguide/connector run as a swept system. However, this would mean that both connectors would arrive attached. It also makes attaching another connector in the field at a later date a problem if you want to maintain an optimized run.
Q: Will we be able to use all existing microwave bands for DTV/HDTV.
A: The bands in question are 2, 6, 13, 18, and 23-GHz. To encode a specified amount of data requires a certain amount of bandwidth for the microwave transmission. Right now, with the encoding systems being considered, it seems that the encoded data will require a 25 MHz channel. This means that the use of 6, 13, 18, and 23-GHz is perfectly practical. The bandwidth of the channels in the new 2-GHz plan is 15 MHz. It would seem likely, therefore, that 2-GHz will NOT be compatible with digital DTV/HDTV traffic. It may well be that the 2-GHz band will really be for analog ENG use only.
Remember that we are all learning together at the moment. All suggestions and comments are very welcome.
(Ed Note: As mentioned earlier, Peter Finch represents a number of companies that deal in RF equipment He is home based in Portland, OR)
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Subj: A Cinematographer's color chart.
By: Jim Mendrala
Gamma 8 Density Company has a chart that the cinematographer use to establish a method to arrive at the "look" they desire during a film-to-tape transfer session and maintain artistic and technical control. The chart is used on the set to establish a standard of communication with the telecine colorist in the film-to-tape process. Now instead of subjective and debatable opinions regarding images, the cameraman and telecine colorist are speaking a common language.
The chart called "The Gamma=1c Cinematographer's Control Chart" has one feature that sets it apart from other charts. That is the patented idea of connecting brightness of the scene with scientifically calculated IRE unit equivalents printed right on each corresponding gray field. This chart creates a proper connection between the brightness of the scene and luminance of the electronically converted film signal. With the use of this chart the telecine colorist is able to transfer dailies with accurate and consistent contrast, color, and tone renditions. This continuity in dailies takes the guesswork out of the transfer set-up process.
The chart is a combination of the gray and color fields. The image captured on film allows the telecine colorist to maintain a consistent transfer.
The company has a web site at: <http://www.loop.com/-gamma1> or can be reached by e-mail at: <gamma1@loop.com>
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Subj: Information available in print
TV TECHNOLOGY, in their June 5th issue have two interesting items -- LPTV, Translator Stations Angry Over DTV Allotments. Also the Harsh Realities of the DTV Allotment Table and Stainless Foresees Boom in DTV. Stainless is a tower company out of North Wales, PA and owns both KTVZ in Bend, OR and WICZ in Bingington, NY. Stainless and its subsidiaries are in the process of being bought by Northwest Communications out of Spokane, WA. -- Digital TV. If you do not subscribe, you can get more information about this issue by calling (703) 820-3245.
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(Ed Note: With all this tower talk we present the following from the CGC Communicator)
Subj: BELT AND HT SAVE TOWER WORKER
From: rgonsett@connectnet.com
A tower repairman for a large utility company is alive today only because he remembered to secure his safety harness and was carrying a hand-held (HT) transceiver. It happened on Tuesday May 27th when the unidentified worker slipped while changing lamps on an eighty foot tower. A tower that was sitting atop a three thousand foot mountain overlooking the city of Victorville, CA.
Being well trained he had instinctively attached his safety harness to the tower before beginning to work. When he found himself dangling from the structure in mid-air, he used his HT to call for help. Even so, it still took almost three hours before rescuers got him down. He was flown by helicopter to a nearby hospital after complaining of back and leg pain. (Extract from Newsline)
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Subj: Tektronix MBD: Technical Briefs -- White Papers & Measurement App Notes
Digital Video Broadcasting And The DVB Project: Over the next few years, the video broadcast industry will change dramatically as it moves through the most significant transition in its history. If the industry were to follow its usual course, the prospect of these changes might be greeted with stalling or delaying tactics, compounded by the slow, cautious development of the necessary (but often competing) technical standards by the industry's business and technology groups. Yet, with the Digital Video Broadcasting (DVB) project, the response has been uncharacteristically rapid and has enjoyed unusual, widespread acceptance.
Breakthrough Technology for Digital Design Analysis Defined by Intensive Market
Research: Tektronix has debuted an innovative platform, concept and product series that redefines the measurement tool used for digital design analysis. The TLA 700 Series is everything needed for digital design analysis -- faster, wider and deeper than conventional logic analyzers -- to meet the challenges of today's convergence era and beyond. With 500 picosecond (ps) timing and up to 136 channels per module, the TLA 700 Series doesn't miss anything.
After almost a decade of growth and development, VXI bus has become the preferred instrument platform for test applications that demand high performance combined with compactness and configurability. Much of the appeal of VXI lies in its ability to form efficient optimized test systems for virtually any application. A huge variety of modular instruments has arisen, from digitizers to switch matrices to digital pattern sources. The test engineer who has a problem to solve can look through the VXI catalogs and specify a system consisting entirely of off-the-shelf modules, yet exactly matched to the test needs at hand. As a result, VXI systems are found in avionics service depots, HVAC manufacturing lines even in food processing plants.
(Ed note: For additional information contact your regional Tektronix sales office.)
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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.
