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Tech Notes

Published by: Larry Bloomfield & Jim Mendrala

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November 22, 1999

Tech Note - 045


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.  Please note the new E-mail addresses. To remove yourself from this list, send an e-mail to:  in the subject place the word Remove.  We now have over 530 subscribers & growing.                  This is YOUR forum! 

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Ed Note:  Jim Mendrala is at SMPTE - New York.  Look for his report soon.


Subj:  Fixing On Air digital Errors

From: Ray Herring


(Ed Note:  Ray is the Transmitter Supervisor at KGO-TV, Channel 7 & KGO-DT, Channel 24,  (ABC) San Francisco, CA)


We ran into a little problem that we didn't know we had with our on air DTV signal.  Gus Fernandez of TeraLogic did an analysis on our off air signal and found that it had about 35 errors per minute.


Our digital signal path starts with our Harris/Lucent encoder.  From there we go to a Leitch Digibus interface, into a DS3 line and then on to the transmitter site. At the transmitter site, it goes from the DS3, to the Leitch interface and then to the exciter.


It seems that the Leitch interface was changing some bits on some of the packets. The Sencore analyzer says the Adaptation Field of the Null Field Packet header was being changed to '00' instead of '01.'  This was causing a loss of some video packets: sometimes one, two or three packets. Most receivers cannot correct for three lost packets and will breakup. The new hardware from Leitch will be installed by the time this Tech Note gets on the street.  Leitch was very concerned about this and was very responsive. 


Anyone who is using a similar setup might like to know about this and check for errors.  For the most part, on air you can't see the result, but add to it, the multipath problems with the present receivers, and you magnify the problem.  Hope this helps someone out. Your newsletter is an absolute gem, thanks.



Subj:  Increasing Optical Media Densities

From: Kurt Hageman -


(Ed Note:  Kurt is an engineer well experienced in audio systems and a sometime inventor.  His list of credits is numerous.)


Well, as you know the DVD was made possible by the blue laser diode.  The smaller the wavelength of the light the closer we can pack the data.  A company, Nichia, in Japan has come out with a 370nm laser diode. Yes, that is black light!! Now we will be able to pack data even tightly.


We could even replace those large fluorescent blacklight tubes, left over from the 1960's, with a solid-state blacklight source.  Wow! It's a whole new way to look at blacklight posters. Anyway the 370nm LED comes with an eye hazard warning. You cannot see the light. Unlike fluorescent blacklights that have some visible spectrum emitted from the phosphor, the LED is monochromatic, you cannot see if it is on and it can damage your eye by looking at it.


I predict that the next step in the evolution is most certainly in the short wave ultraviolet range, i.e., UVB or UVC, black light is UVA. This will increase the density of optical storage.


An application of this technology and as a side note, when are they going to increase the sampling rate on audio CD's?  44.1KHz is not fast enough to properly reproduce the complex harmonics generated by classical, jazz, and other music styles.  All the sounds combine and produce very complex harmonics and are not replicated by sampling at 44.1KHz. If we can get all the video information on a DVD read with blue laser light why not improve the audio CD?? Look at it this way, the audio CD is in its original form: the same as the Edison cylinder was the first form of groove recordings. I want to see the CD process evolve up to where LP's were when CD's took over. I can hear the differences between the CD version and the LP version of a particular piece of music. The LP has a warmer more musical sound. Now we are talking about classical and jazz here, not this #*&!% that is put out today, it would sound just as bad no matter how you recorded it.



Subj: A "bit" concerning encoder comparisons.

From: Jerry Surprise


(Ed Note:  Jerry works for Panasonic.)


A most remarkable test was done this week (circa 11/16/99) at the Model Station Technical meeting in Washington, DC. Amidst many demonstrations, a test was done with the encoders loaned to the Model station.  Five different encoders encoded the output bitstream of the Sarnoff Digital Television Encoder Stress Patterns, with the decoded results shown on monitors that were positioned in such a way, that it was easy to compare the final results.  NDS, Tierman, Divicom, Mitsubishi and Thompson supplied the encoders.  After looking at the pictures for some time, it became very apparent to me, that the Divicom encoder was the best encoder. It had far less artifacts than any of the other encoders. The next best encoder was the NDS encoder.  (Ed Note:  We have not included the worst encoder)  This test and comparison was unique and will not likely happen again in the future.  Divicom was reported as having more MPEG experts than any other company in the US. The Divicom encoder uses "LookAhead" technology for a more constant bitrate and "ClearMotion" Integrated Noise Reduction.

Thanks again for your Newsletter.



Ed Note:  If the next two stories aren't a wake up call to the cable industry to do what is necessary to bring good, crisp pictures into subscribers homes, they can begin the count down to their demise.


Subj: EchoStar plans Local Channels; Congress finished, finally!



LITTLETON, CO -- Nov. 19, 1999--With final passage of satellite TV legislation, EchoStar Communications Corporation will begin providing better competition to cable by offering local ABC, CBS, NBC and FOX network channels to consumers.


Within 24 hours of President Clinton signing the bill into law, EchoStar's DISH Network will offer consumers in Atlanta, Boston, Chicago, Dallas/Ft. Worth, Miami, Los Angeles, New York, Pittsburgh, Washington, DC, Denver, Phoenix, Salt Lake City and San Francisco their local channels by satellite. Consumers across the country living in areas where they are unable to receive a local off-air broadcast

signal will continue to be offered distant network signals. EchoStar also plans to launch local channels by satellite to 30 total markets next year.


"Congratulations go to the broadcasters for a hard-fought victory in Congress," said Charlie Ergen, CEO and chairman of EchoStar. "We're disappointed that the bill didn't go further to protect the rights of consumers and does not allow consumers the freedom of choice to watch the network channels they choose. The legislation also should have done more to foster competition by creating better equality between cable and satellite TV providers. With no statutory guarantee of fair pricing, the best we can do is hope that the broadcasters will not demand terms and prices from us that are higher than cable pays and that will raise costs to our customers and keep us from competing effectively with cable."


EchoStar first approached Congress three years ago with the intent to protect the rights of consumers and to seek competition to the rising rates and poor customer service of cable television.  "EchoStar extends a heartfelt thanks to those in Congress who backed the fight for the rights of millions of consumers and to the hundreds of thousands of consumers and retailers across the nation who made phone calls and sent e-mails and letters to Congress in support of a bill that offered a true alternative to cable TV," Ergen added.


"We look forward to working with the broadcasters and Congress in 2000 to further create effective competition to cable television and, in particular, to address the needs of rural customers who seek  popular network programming."


Subj: DIRECTV Applauds Passage of Satellite Home Viewer Act



EL SEGUNDO, Calif. -- Nov. 19, 1999--DIRECTV, Inc. today applauded Congress for passing the "Satellite Home Viewer Improvement Act of 1999." The bill permits improved competition between satellite carriers and cable operators.  The bill allows satellite TV companies -- for the first time -- to offer local broadcast network channels, and it also provides a five-year reprieve to hundreds of thousands of consumers who were scheduled to lose distant network signals as the result of a federal court decision earlier this year.


"The passage of this legislation is a tremendous win for consumers and ushers in a new era for satellite TV," said Eddy W. Hartenstein, president of DIRECTV. "Every month, two-thirds of our new customers come to DIRECTV from cabled areas, which underscores the need for enhanced competition in the home entertainment industry. Upon President Clinton signing the bill into law, we will begin offering local channels to major metropolitan markets throughout the country -- finally leveling the playing field between satellite and cable."


As previously announced, DIRECTV will offer local broadcast network channels via satellite to up to 50 million homes, or about half of the nation's television households. DIRECTV will begin rolling out local channels in Los Angeles and New York within hours following the President's signature of the new law, and will continue adding markets throughout the remainder of 1999 and in 2000.  In addition to Los Angeles and New York, the first markets to receive this new local channel service include San Francisco, Washington, DC, Denver, Detroit and Miami. Additional markets will be announced in the coming weeks as the rollout continues. 


DIRECTV customers will be able to subscribe to their local channel package -- which will include a national PBS feed -- for $5.99 per month.  DIRECTV will deliver local broadcast network channels in approximately 20 markets from its satellites at 101 degrees West Longitude (WL), its primary orbital slot. As a result, DIRECTV customers in those markets can receive their local channels as well as DIRECTV's current lineup of national digital entertainment and information programming through their existing digital set-top box and 18-inch antenna.


DIRECTV will deliver local channels in additional cities from the 110 and 119-degree WL orbital slots. Local channels delivered from the 110 and 119 degree WL orbital slots will be received via the new DIRECTV Plus System, which features an 18-by 24-inch oval satellite dish. The DIRECTV Plus System also receives and seamlessly integrates the existing lineup of popular networks, premium movie services,

pay-per-view selections and sports programming subscriptions from 101 degrees WL.


DIRECTV has approximately 7.8 million customers, including customers subscribing to PRIMESTAR By DIRECTV. Visit DIRECTV on the World Wide Web at


Subj:   Mark Schubin's visit to NxtWave

From:  Mark Schubin


(Ed Note:  Since Mark was there and saw first had, we asked his permission to reprint this from one of the Internet lists we both subscribe to.  We're grateful for his kind permission.)


I went to NxtWave on Friday afternoon. I was not asked to sign any nondisclosure agreement. I visited their lab and the demo setup in CEO Matt Miller's office. I also got to sit in on some discussions with

some other guests who HAD signed NDAs, which eventually made NxtWave uncomfortable (as it should have). I left NxtWave at my own pace; they didn't shoo me out.


My findings:


- The NxtWave equalizer is effective. In the lab, we adjusted to a condition of "completely closed eye" pattern (actually, for 8-VSB it's eight lines rather than an eye). For those of you who have seen demos

of the Tektronix equalizer for SMPTE 259 built into the WFM 601 series of waveform monitors, the effect was similar: without equalization mush, with equalization eight distinct lines. NxtWave's goal is to be "best of class" (i.e., the best 8-VSB equalization). I do not have sufficient experience with all the alternatives to say whether they have met that goal, but I would say that this was the best 8-VSB demodulation I have yet seen.


- It is not magic, however. The present algorithm could not always handle a zero dB static echo (sometimes it could), for example. It also has some problems with very close-in echoes. The NxtWave people believe that they know what needs to be done to fix these problems and plan to do so in second-generation chips. There is, however, a practical limit to how much can be done at a certain level of power consumption and chip cost. The current package (100-contact plastic) draws about 1.2 watts.   NxtWave's goal is for the chips to be able to live in PCMCIA cards. An increase in equalization complexity that raised the power level to over two watts would mean different packaging for heat removal. NxtWave,

therefore, has to weigh what is technically possible with what makes business sense.


- There is no manual intervention required to handle different echo ensembles, nor was any manual intervention used in the "real-world" demo other than to change channels and orient the antenna.


- The ability to handle dynamic multipath was demonstrated in the lab.  The appearance on the spectrum analyzer was that of a waving flag. The other guests and I both noticed, however, that the effect of the

equalization on the dynamic multipath was not constant. At one point in each cycle, which appeared to be when the notch was in the vicinity of the pilot, the pattern closed a little. There was clear correlation

between the pattern closing and the frequency of the dynamic multipath, but I cannot say for sure that it was at the pilot.


- There IS a sensitivity reduction caused by the equalizer, but it's not a lot. I saw demodulation at a C/N in the vicinity of 15 dB. With a ghost ensemble (I personally viewed ensemble "A" being tested), the

reduction was on the order of 1.0 to 1.5 dB (C/N around 16.5 dB).  NxtWave's specs submitted to the FCC claim the same reduction for ensembles "A" through "G."


- The field tests conducted by NxtWave (which I did NOT personally see) were conducted under conditions similar to those used in the non-Sinclair testing: van, 30-foot mast, log-periodic directional antenna on a rotator. The big difference is that there was no MPEG decoder. They tested based on "eye" (line) pattern. I believe that to be valid methodology (I also believe Sinclair used valid methodology in its tests -- in both cases one could argue about the equipment used and sites selected).  You may wish to take this entire section with a grain of salt because it's secondhand, but I think there's a very important point at the end that is quasi-first hand. I'll concentrate on just the Philadelphia field tests.  There were seven sites: Sites 1-4 were NOT in center-city locations; sites 5-7 were. Sites 1-4 were said to be successful on all four Philadelphia DTV stations. That means that, with the antenna rotated for maximum signal strength, a clear eight-line pattern was demodulated.  Sites 5-7, the inner-city sites, were NOT successful on all stations. It is said that CBS was okay at all sites, ABC less so, and NBC and Fox not receivable. That's in approximate descending order of transmitting-antenna height and effective radiated power.


Now comes the quasi-first-hand stuff: NxtWave personnel described what they called a "tunneling" effect at the bad sites, where a signal bounces back and forth between buildings, creating a very long ghost.


We discussed this at length and eventually got around to what it looked like on a spectrum analyzer. We were at the demo setup at the time and had a spectrum analyzer in front of us so we could point and gesture and say things like, "It looked like that part, but maybe 10 dB peak-to-peak."  As a result, we came to the conclusion that what the NxtWave personnel had seen at the inner-city sites where some DTV stations could not be received very closely matched what I had seen once before. The place I had seen it was at the high-rise, Inner Harbor apartment site at the Sinclair tests in Baltimore.  Take this for what it is worth. What is odd about it is that the NxtWave personnel believe that problem to be caused by a very lengthy echo, which would supposedly cause a problem for COFDM if it exceeded the guard-interval length. Yet, there was clearly perfect and stable COFDM reception in the apartment; it was the 8-VSB receivers that failed. I was there. The Sinclair personnel couldn't understand why the 8-VSB had failed there, since there were no huge nulls visible on the analyzer.


- NxtWave plans to send a team to my apartment to record the DTV spectra and take them back to the lab for testing. They say they will tell me:  a) whether they could demodulate the signals at all, and b) whether they think they could be demodulated cost (and power) effectively. I like the idea of the famous (infamous?) Schubin site. They also reminded me (DUH!) that, even though I can't get DTV reception in my apartment with the receiver/decoder and antennas available to me, I COULD see what the spectrum looks like. As soon as I get a chance, I'll drag over an analyzer and have a look.


- Now to the meat: The "real-world" demo. NxtWave is using a thrown-together setup with different manufacturers for the different components (tuner, SAW filters, MPEG decoder, etc.). The MPEG decoder was not always working well (it appeared not to always refresh with I-frames), but I did not have any difficulty distinguishing between a decoder problem and a demodulation problem.


- I decided to compare apples and apples. When we walked over to the demo setup, an NTSC receiver was tuning in the CBS analog station in Philadelphia on rabbit ears, and the NxtWave setup was getting the CBS digital via a directional UHF antenna. The CBS analog looked awful.  BUT the CBS analog is VHF channel 3. I asked for an analog UHF near the CBS digital (channel 26). We chose a Fox station (WTXF) on channel 29 and split the antenna three ways (to the analog TV, to the DTV receiving apparatus, and to the spectrum analyzer). The analog station came in superbly. I would rate the analog picture quality as "very-good to excellent." NxtWave personnel wandering by glanced at it and said,  "Wow! How'd the analog get so good?"


- The strange antenna referred to in a previous posting about NxtWave is a Silver Sensor "Antiference" indoor set-top yagi from the UK. It was possible to use it to get not merely excellent analog reception but also perfectly stable DTV reception that was not affected by our walking around the room behind the antenna. The antenna DID have to be positioned, but that was pretty easy, and NxtWave's chip offers a tap-energy output that can be used as a positioning indicator (or for Charles Rhodes' crossed-dipole electronic-steering idea). The antenna was about six feet above the floor on a stand.


- We also tried a standard cheap UHF bow tie of the sort packed with every TV set in the US (it was also one of the antennas used in the Sinclair testing). Its positioning was more critical, but it, too, could be positioned so as to provide absolutely stable DTV reception.  There was not "just one" position in the room for it. Perfectly stable reception was possible from a height of only about four feet. The bow tie, too, was not affected by our merely walking around the room behind the antenna, but, with a metal chassis-grille plate, I COULD cause reception to fail at certain points (looking at the spectrum analyzer, I could also IMPROVE reception, with the plate acting as a back reflector).


- Please note that, while we were able to make the DTV reception fail (by misaligning the antenna or stalking it with the chassis plate), we never got the ANALOG to fail completely. Channel 29 looked great.


When we tested ABC's digital at channel 64 and NBC's at channel 67, we switched to an analog Philadelphia station (WPSG - UPN) at 57. It wasn't as good as WTXF, but it, too, was quite watchable when the DTV failed. We passed other, perfectly good UHF signals between 29 and 57, too. It is clearly not the case that there will always be DTV reception where there is analog reception.


Please also note: From NxtWave's offices, the Philadelphia stations (analog and digital) are all essentially co-located. BUT, without moving the antenna, we also got good reception on channel 58, an analog New Jersey Network (PBS) station (WNJB) in New Brunswick, New Jersey, in the opposite direction (and probably farther away).  I'd say the Philadelphia stations are some 25-30 miles from NxtWave. Based on my previously driving and taking a train over a similar route, I'd say the terrain is relatively flat (some low rolling hills). There IS a road outside the demo-room window, but it is considerably lower (at no time was there any correlation between road traffic and reception). There are trees, however, across the road, which the signals probably have to pass through.


- At no time when there was successful DTV reception at the NxtWave demo did the spectrum analyzer display appear to be anything like what I saw in Baltimore. There were no multiple deep notches or slopes.


Furthermore, while I could see myself affecting the spectrum display as I moved around the room, I had to look carefully to see the effect. In Baltimore, at the 10 West Lee Street site, we all felt we had to stop breathing lest we affect the test. The slightest hand motion was clearly visible on the analyzer, and, again, we were standing behind the antennas.


This is not meant in any way as a criticism of NxtWave's demo.  They did not do anything to prevent my affecting the spectrum (although the antenna was positioned closer to the window instead of farther from it). It's just very clear that the sites were quite different. That's to be expected. I saw inner-city sites in Baltimore; NxtWave's offices are suburban.


- There WAS, however, a spectrum problem I noted at the NxtWave demo that I never noticed in Baltimore: impulse noise. I might not have noticed it in Baltimore because there I was looking only at DTV spectra. At NxtWave, when we were looking at ANALOG spectra, little spikes would pop up here and there amid the three NTSC peaks.


- Other items:


- NxtWave has never called their chip a "miracle" and objects to that characterization. I will cease to use it henceforth.


- NxtWave personnel seem to feel that diversity reception would be necessary for 8-VSB mobile applications.


- NxtWave has looked at a lot of DTV signals from a lot of stations. "Some of the signals we've looked at give us concern about the consistency of VSB encoders/modulators," said CEO Matt Miller.


- NxtWave's chip works fine with QAM as well as VSB.


That's about it. If anyone has questions for me, I'll try to answer them ( You might also try Matt Miller (





Subj:  E-cinema, may be not!

By:  Larry Bloomfield


Electronic cinema is on the verge of climbing into bed with HDTV.  To let you know where I stand on this, keep in mind that today's NTSC pictures delivered via digital satellite is comparable to super 8 mm film.  If that were the case, HDTV is then comparable to Super-16 mm film.  Since Electronic Cinema must measure up to 35 mm in it's worst case, there is no way that this new burgeoning industry can or should ever settle for glorified HDTV, irrespective of who is doing it or whose name is on it.  Don't get me wrong.  There is nothing wrong with HDTV, for the home, but put it on a theater screen and what you see is what you get.  Yuck!  The numbers don't lie, irrespective of who says anything different. 


There's no question that the HDTV performances (i.e. Star Trek and Toy Story II) that are or have been given at various venue to date, using the HDTV equipment, has look quite impressive.  But why should the electronic cinema industry settle for a skateboard when they should be thinking aircraft?  It's time for the nontechnical types to get the hell out of the way, stop interfering with their political BS and patronizing old cronyism and let the engineers, who know what they are doing; get to the business of developing the standards and technology worthy of Hollywood's glorious history. 


This whole business of letting the big manufacturers bamboozle this new industry into using the relatively inferior products and not address where they have to go to measure up, is absolutely ridiculous and stands against every ethical standard any engineer of worth would subscribe to.   It reminds me of a talk given by one of Thomson consumer products VPs in Palo Alto, CA, about a year ago, when he stated that his company's TV sets would be able to display up to one million pixels.  When asked why he was bragging about displaying only half the pixels the broadcasters were transmitting, he neglected to address the issue.


Settling for HDTV as the electronic cinema standard is comparable to that VP's line of thinking.  35 mm film is a 4,096 by 2,214 pixel format (per the SMPTE Journal, Nov. 1999, page 753).  HDTV is 1080 by 1920 (per ATSC).  You do the math!  Qualified Engineers, not people with high-priced corporate titles, have always been the ones to get the job done.  It's time for the "suits" to sit down, shut up, and let the people "in the know" do their jobs.  


Am I trying to stir the pot?  You had better believe it!  What to mussel me?  Hire me; I usually don't bite the hand that feeds me!  These are my opinions, from my prospective: more on this later. 



(Ed Note:  The Editors and Publishers of the Tech Notes wish to thank Des Chaskelson, Research Director of SCRI International for his generosity in posting the Tech Notes on the SCRI web site.  


From:   Des Chaskelson, Research Director, SCRI International (

Re:       New Website with Industry Press Releases Plus New HDTV Survey


Check out the SCRI web site, where the Tech Notes are published, for some really great information on industry trends and other very valuable marketing information, trade news and current television events.  SCRI is currently in preparation of our latest survey, analyses and report.  Stay tuned!


The Tech Notes are published for broadcast professionals, and others, who are interested in DTV, HDTV, Electronic Cinema, 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 (419) 710-1913 or (419) 793-8340.  (Please note Larry's new e-mail address). 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.