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 Some of the information may be out of date.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
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--------------------------------------------------------------------------July 21, 1997
NWTN - 006
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---------------------------------------------------------------------------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. We need you to share your experiences, knowledge or anything else relating to DTV, HDTV etc. 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 we've 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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From: rgonsett@connectnet.com (Bob Gonsett) ----- and the THE CGC COMMUNICATOR (Electronic Edition) #170 - Wednesday, July 16, 1997
DTV TRANSMISSION STANDARD VOTE SET FOR NEXT WEDNESDAY
John Henderson, who chairs the ATSC committee responsible for "Compliance," indicates that the Digital Television Transmission Measurement and Compliance standard will be voted on this coming Wednesday, July 23. We plan to publish the URL where the document can be viewed assuming the vote is favorable.
This document will not answer all questions. Work remains to be done on channel and digital "sub channel" identification, on interoperability, on data broadcasting, on layered video and the like. However, publication of the Measurement and Compliance standard will move the RF folks a giant step forward.
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(Ed Note: Several years ago Dynair had an interesting thing they called "The Order of The Iron Test Pattern." I know several other engineers who happily displayed the membership certificate etc. I always thought it was kind of a fun thing. Bob Venderland, through Bob Gonsett, has written us here at NWTN with the following. He is trying to revive "The Order of The Iron Test Pattern." In addition to what is below, you might contact him or visit their web site to see what it is all about. LB)
From: Robert Vendeland <rnvendeland@io-online.com
The Order of The Iron Test Pattern is starting a speaker's bureau which may be of interest to some of the recipients of your digital television news letter. In many cases a television engineer would welcome the opportunity to talk before a local service club in his or her community on technical subjectssuch as the impact of digital television on the consumer. However, most engineers we know hesitate to push themselves forward as volunteers.
It is for this reason that the Order plans to introduce, on our elegant letterhead, interested engineers to the program chairmen of Kiwanis, Rotary, Chambers of Commerce, etc. in their communities. Our letter will say that (the engineer, resume and photo will be enclosed) is in our speaker's bureau and is prepared to talk to their group on the (subjects selected by the speaker). We will send a brief description of the Order, and the fact that we survive because we have a sense of humor and can explain complicated concepts to management in words they understand.
To make this happen, we request that the volunteers send a very brief bio-sketch to us along with a photo that we can scan and laser print for attachment to the letter of introduction. Our letter will contain all information necessary for the program person to contact the engineer directly to make whatever arrangements are acceptable to the engineer.
Except for the introduction, we are not in the loop. We'll send up to three letters per volunteer and are confident that this service will be of great public relations value to the engineer and the engineer's employer. Most important, it has the potential for bringing more fact than fiction to the public ---- especially in the area of digital television.
Our address is:
Order of The Iron Test Pattern5751 #D Palmer WayCarlsbad, CA 92008Attention: Robert Vendeland, MarshalE-Mail is: rnvendeland@io-online.comWeb Site is: logoinc.com/irontestRobert N. Vendeland
E-Mail: rnvendeland@compuserve.com********************************************* (Ed note: Eric Dausman is the Director of Engineering at KGW in Portland, OR. Eric was a significant contributor to the SBE luncheon recently in Portland on the subjects we speak about here in our newsletter.)
From: EricD@kgw.com (Dausman, Eric)
Here are some comments I passed on to the AH Belo organization.
Subject: DTV Discussion
I'm a little confused. Why are we debating the politics of the DTV mandate that has been essentially cast in stone? DTV is our future, especially if we go do it, and do it smartly. Consumers have been asking for better television for years. They just didn't know what to ask for. The major complaint has nothing to do with scanning lines, and resolution. The big issues for most consumers are ghosts and snow.
I spend a lot of time on the phone with viewers talking about TV reception.
We are giving away a lot of our NBC viewers to satellite every month for one reason only. They get a much better picture off the DSS dish! We can not compete with a crisp clean picture void of any ghosts or noise in the rural areas of our market, and even in some of the urban and sub-urban areas.
Viewers are getting smarter and smarter. They are demanding better video. If we do not provide it, someone else will. I believe that our analog days are numbered simply by the fact the electronics industry is going to push digital video "stuff" such as TV's, VCR's, even games, because it is good for their business. In the end, most consumers will not buy a new TV on the specs for lines of resolution, but for how many inputs does it have to take advantage of digital technology. Remember how fast they changed the record industry. Everyone complained at first about the high cost of machines. Within two years of the introduction, there were $199 CD players. No one ever spent $199 on a turntable for their stereo. Consumers were willing to spend the additional money because they saw the add value of the CD!
Everyone seems to agree on one point. There will be very few true HD
displays available to the public simply because of the cost. In my opinion, true HDTV is at the bottom of the consumers list of features they want.
First, they want good looking images, void of ghosts and noise. Second, they want larger screens, wide would be nice. Third, they want decent audio. Decent audio does not need to be surround sound. It just needs to be good and clean, and the commercials better not be louder than the program material.
It goes without saying that consumers expect that the new TV set will be compatible with existing NTSC, DTV signals, cable digital signals, DSS signals and the like. There will be some sort of consumer video jack standardize for home use, and it may be as simple as analog component signals or maybe eventually truly digital. This way they can plug all the components the electronics industry is going to sell them together.
Nowhere on this list is more TV channels or "laboratory grade" HDTV! It will simply be to expensive a "feature" to be purchased by most.
Enter DGTV resolution--
Now, how do we get the consumer what they want? We all know that we could deliver better pictures from our studios than we can deliver to the home. Some of us already do this. (KGW is not one of them. I still air news on 3/4 inch, remember!) This is simply because our origination and production equipment can now be much better than our transmission system will allow.
We should equip ourselves to do the best job possible for the foreseeable future--that "infinite 5 years". The only way we can do this at a reasonable cost and in the allotted 18 to 30 month time frame is with good quality stuff we can buy now. This means that we should be looking at a widescreen 525 line rate component serial digital plant with the added bits for widescreen. Lets call this Widescreen 525 CSD or W525CSD for short. I think SMPTE has another name for this by now. I call meeting the consumers need for lack of noise, lack of ghosts, wider screen, and better audio, DGTV, which is short for Damn Good TV!
We could buy some true HD routers, switchers, and even DVE's now, but you will not be able to deliver the production value to your programs that your viewers are accustom to. Besides, they are way to expensive.
If your network really provides you with a HDTV signal, then you will need a bypass path around your production systems, and a down-converter to bring the signal into your W525CSD. This will allow you to integrate commercials, ad supers, dissolves, and all those things the promotion department wants. At the output of our "master control" we will need to be able to up convert to DTV, and encode to NTSC. The best part of all of this--our NTSC is going to look better than ever!
As a group, we need to consolidate our thinking into one voice. Don't get me wrong, I am not against buying true HDTV equipment, I just feel that the viewer may never see it until the second "infinite 5 years". Until then, DGTV will suffice, because this is what the consumer wants, and this is what will be available.
I plan to comment about many of the other issues, but I have other stuff to do like change a light bulb above an anchors desk. Yes, I have to do that kind of stuff, too!
Eric
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Subj: Digital Encoding
From: pjfinch@worldnet.att.net (Peter Finch)
Gentlemen:
In my last few e-mails, I have stated that MRC will use 34 Mbps QPSK to encode DTV/HDTV signals onto a microwave radio.
As I said, we are all learning. 34 Mbps is the European standard. MRC will be using 45 Mbps.
Regards - Peter Finch
Northwest CommunicationsVoice 503/632-7488FAX 503/632-4563******************************************* From: rpdark@hdvision.com (Randall Paris Dark)
You said in your last issue: "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."
I may have not been clear. I have been producing High Definition for about eleven years but only the past 4 years have I been doing it in Digital HD. The different formats are based on the clients budgets. Some clients can afford the HDD-1000 VTR's, some clients can only afford THE Uni-hi format. However, all of the clients use the production standard of 1125/60 Interlace.
Randall
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(Ed Note: NWTN was sent a copy of this e-mail correspondence for publication as it may be of interest in the new HDTV world. Additionally we asked a local dealer to get us a DXC-9000 for purposes of evaluation. We will advise our readers as to our findings.)
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From: "Jeremy Pollack"
Subject: alternate summed pair lines
Greetings Jim
You commented, "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."
FYI - I understand Sony's HDC-500 (HD CCD camera) captures this way too, as indeed many CCD cameras do. On the CCD (integral with the chip), 1/60/sec sampled Frame is actually output (off the chip) as alternate summed pair lines, so presented as interlaced fields. (I.e., field 1 = Frame1 lines 1&2, 3&4, 5&6..., field 2 = Frame2 lines 2&3, 4&5, 6&7...) BTW: Advantage is effective halving of CCD noise.
Sony will not acknowledge this is what they do... IAC, output as 1/60 Frames is only on-board the CCD itself, and not available as an external signal.
Regards
Jeremy
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Mendrala's reply:
Dear Jeremy,
You are correct about a conventional CCD image sensor, the vertical resolution is only about 350TV lines because of field integration techniques to match NTSC broadcasting specifications. This was the result of the NTSC standard, which uses two fields, each 262.5 scanning lines, interlaced at 2:1 to create a single frame. since emphasis was placed on making the motion of a subject appear smooth rather than providing a high vertical resolution, the conventional CCD (IS-4T) mixed signal charges from two adjacent pixels vertically, outputting 262.5 line signals per field (i.e. per single exposure). The vertical resolution is still insufficient compared to horizontal resolution. To resolve this problem, Sony developed a progressive Scan CCD image sensor, which does not mix signals in the vertical CCD.
The new DXC-9000 camera provides three types of output signals, a 2:1 interlace scanning system that can run in the "Normal Mode" (NTSC standard), outputting RGB, Y/C and VBS, a "Frame Shutter Mode" (NTSC standard), outputting RGB, Y/C and VBS and a VGA mode with a 640 x 480 RGB output.
In the "Normal Mode" the odd field is provided from one image in 1/60 second and the even field is provided from the next image 1/60 second later. The odd and even field are output one after another, then interlaced together to form one frame.
In the "Shutter Mode" both the odd and even field are taken from the same image in 1/60 second. The even field is put in memory and output after the odd field, then interlaced together, in accordance with the 2/1 interlace scanning system. When a high-speed moving object is shot, each frame image is clear, because both the odd field and the following even field are from the same image.
In the "VGA Mode" the camera produces an RGB VGA format with 640x480 signal. This works with non-interlaced computer monitors. This is possible by increasing the horizontal scan rate.
The Progressive Scan method can read out information for each pixel individually in a single field (1/60s), providing both high vertical resolution and high dynamic resolution.
The field and frame output signals allow the camera to maintain complete system compatibility with existing video equipment. The camera is also available as a progressive PAL camera.
In the film world, an image is photographed (captured) in 1/50 second at a frame rate of 24 per second. When these frames are scanned on a telecine scanner each image is stored in a frame store and output as a standard NTSC signal which is equivalent to the "Frame Shutter Mode" of the DXC-9000.
FYI: Price of the DXC-9000 starts at $6,500 w/o lens or optional accessories. The camera is designed to accept 1/2-inch, 38mm bayonet-mount lenses. The lens mount has a dual hot-shoe connection to eliminate the need for a lens-to-camera interconnecting cable. This provides easy remote control of zoom, focus and iris functions. 2/3-inch mount lenses can also be used with an optional Lens Mount Adapter.
Jim
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Larry's Notes
by Larry Bloomfield
I want to thank all those who have shown such a positive interest in our NWTN publication and a special thanks to those who have contributed their thoughts to these pages. This past week was really great for me. I had the chance to travel over the Cascades into Portland. A normal three hour trip that the road maintenance folks added an unsuspected half hour or more to. It was worth all the trouble. The occasion was the monthly SBE meeting.
It is the grass roots engineers who have always come up the solutions to the most complex of issues in our industry. It was a pleasure to meet and speak with those in attendance and a special thanks to the Portland SBE for permitting me to share some of my views about DTV, HDTV etc. with them. I feel we had a good meeting. I very much enjoyed the various views and opinions that were expressed. If you don't go to SBE meetings, you really should. Bring up some of the issues we address here in NWTN and you'd be surprised at what others think and believe.
Sorry to the radio guys who were there, but yes, we TV types do talk about the picture part of our business and, in many respects, tend to forget about. The sound systems on TV receivers has certainly improved over the old 3 inch speaker stuck in the side of the plastic cabinet.
Having come from radio originally, as I'm sure many of you have, we TV types can surely make good use of the experiences the radio guys get in their areas as they see the development and improvements in audio technology. The expertise these gentlemen, who deal with audio on a more intimate day-to-day bases, tend to develop a knowledge which should be shared with all of us. There are also some interesting development in the area of digital radio. Perhaps some of the techniques that are being used in this area of broadcasting might have an application in television.
In any event, I have always said, in jest, that you haven't lived the life of a true broadcast engineer until you have had to build a multi-tower AM station from the ground up. (Only someone who has done so can appreciate what I am alluding to here.) Ah the tramping through neighbors yards with your Potomac on your shoulder. Enough of that.
One of the things mentioned was that we need to look at the changes in our industry in two lights. One: generation and Two: distribution. It would appear that we've almost succeeded in getting the cart before the horse. That is to say that we have the RF part of the transition to DTV fairly under control, but as was mentioned in our Portland SBE meeting, what the RF carries is still up in the air. Until we know what the set manufacturers are going to do, we won't know what to generate in our plants. To be safe, as has been said in these pages before, buy what ever will capture the highest pixel rate (information). This can then be stored in a multiplicity of formats for recalled and translation to what ever format may be required. The reason for mentioning this is that many station are looking at new gear in the not too distant future. It does not look good for an engineer to recommend something that will be obsolete or unusable soon after it is purchased. Your comments are most welcome. Larry
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In our next issue I hoping to have some information from Tektronix about Digital TV Measurements. If you know of other manufacturers who are making test equipment in this area of our business (DTV etc), please advise. Let them know about NWTN or let us know so we can let them know. Also if there are any consultant engineers reading these pages who deal with RF and are involved with what we cover here in NWTN, please let us know what you are doing and if there are any instances worth sharing with your fellow engineers. Everyone with something meaningful will get space in these pages. LB
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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. News items, comments, opinions etc. 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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