Anablog

Well maybe not everyone, but at least the newspaper of record, the old gray lady, the New York Times, has a nice article about the coming disaster of digital television (DTV). In trying to clarify things, the article actually confuses us more, since they neglect to mention that pretty much any television sold in the last two or three years is already digital ready. They never mention the one operative acronym: ATSC tuner. That stands for Advanced Television Systems Committee. The word “committee” should tip you off as to why this is a disaster, especially when you realize the committee is full of multinational corporations. It is a wonderment it works at all.

It took something like 20 years to come up with standard, in a large part because all the multinational companies had to keep fighting to get their patents woven into the standard so they can reap licensees. Yeah, it’s just another Betamax/VHS or Blueray/HD-DVD fiasco, except this time you can see the corporate greed every time you flip on the TV. My buddy Ricardo, who worked for a company making demodulators for ATSC says: “Its way too complicated.” He sent me an article describing the problems that were arising with DTV. I believe it was Ricardo, along with other engineers that pointed out: “They picked the wrong modulation.” ATSC uses vestigial sideband (VSB) modulation, when, by the time it came out, they should have used quadrature amplitude modulation (QAM) like the cable companies use. The VSB is one reason that DTV is so susceptible to multipath and interference. The word vestigial in the name should give us all pause, since it presages the sensitivity to interference that DTV seems to have.

I will print that letter I got from a working TV engineer below. It is not encouraging. I called him up and he told me they are already getting complaint calls from people that are ten miles away from the transmitter with a clear line of sight to the tower. He maintains that the ATSC standard was predicated by FCC rules that allowed an antenna 30 feet in the air with a rotator. I have not found confirmation of that, but it seems to be the case. Now lets not all panic. If you have cable or satellite, DTV won’t effect you, although the cable companies are going to move their analog channels to digital just so they can charge you more money. I have a letter from analog guru Paul Grohe that will explain that at the end of this post. This is just the normal rapacious cable company behavior, they will be able to charge you more for a “digital tier”, while using digital compression to pack in ever-more channels and at ever-lower quality. So back to DTV, first let’s look at that letter I got from Robert Getsla, a real working TV engineer:

I want to thank you for finally saying to the electronics design community something that those of us in broadcast engineering have been saying for several years now. Please hold the "White Space" decision until after the DTV transition has taken place. There will be enough problems from that transition because of design mistakes in the DTV plan. For example, the FCC [Federal Communications Commission] assumed that everyone can use an outdoor antenna mounted 30 feet above ground, with a low noise amplifier mounted at the antenna to overcome transmission line loss, and a rotator to reduce multi-path. Unfortunately, the vast majority of TV viewers cannot install or use such an antenna.

Our station has been running a full power DTV signal for several years, but as we near the analog TV shutdown date, we are receiving lots of emails and phone calls from our viewers, asking us if we are on the air in DTV, because they can watch our analog signal, but they cannot receive our digital signal, even though we are running only 3 dB below the absolute maximum DTV ERP [effective radiated power] limit.

I think the FCC made 2 serious mistakes. First, they reduced the transmitted signal levels of DTV stations relative to analog TV stations, apparently on the assumption that the analog power levels were so high because they had been established in the vacuum tube era, but we now have much higher performance solid state devices for the front ends of our TV sets, therefore less RF power would be required. Secondly, the FCC chose 8VSB instead of COFDM [coded orthogonal frequency division multiplexing]. 8VSB as a modulation scheme is considerably more "fragile" than COFDM, and does not survive in a multipath environment, whereas COFDM sometimes actually improves in the presence of a small amount of multipath.

But there also are problems with what is called Brute Force Overload, or BFO. Mr. Dane Eriksen is a partner in a well-known consulting engineering firm. His firm; Hammett and Edison, Inc.; was called in to help resolve the DTV reception problems mentioned in the following paper (pdf).

Based on what I have seen and heard, I am expecting a "train wreck" in February, when many people in our audience will lose their over the air reception of KTSF. And that is without any BFO problems from unlicensed "white space" devices. I believe the principle cause of this train wreck is the long term attack from the Cable TV industry trying to force people to pay for "Free" TV reception through zoning changes and restrictive "covenants" placed in their deeds, prohibiting the use of outdoor TV antennas. In our market, 75% to 80% of the over the air TV viewing audience actually is watching their "Free" TV through either a Cable TV system or through a digital Satellite TV antenna, for which they pay monthly fees.

I believe the "analog shutdown" will effectively force many of our audience who are not now paying for their TV reception, to become Cable or Satellite "Subscribers" because that will be their only way to view our signal. In a few more months, we might well witness the death of "Free" TV for most people. And this will happen without any "white space" devices jamming our TV signals.

If you live in a strong signal area you should be able to get most DTV stations even with a set of rabbit ears. You might have to move them around for different stations, but at least you will be able to see the stations, and my, oh my, when DTV works it is breathtaking. I just watched Charlie and the Chocolate Factory last night on channel 7.1 and it was stunning. This is because I get a strong signal and also because channel 7.1 only shares its bandwidth with two other channels, 7.2 and 7.3. Allowing broadcasters to put out 5 channels in the same bandwidth as a single analog channel used to occupy was one of the key ways the FCC sold the TV stations on the whole digital TV scheme. Who would not want 5 stations where you used to have one? The FCC and all the multinational corporations that were trying to get their patents into the scheme did not mentioned that when you broadcast 5 stations at once the quality of the pictures is horrible. My friend calls it blockified, like a crappy jpeg from the Internet.

Can you see Abe Lincoln in this blockifed pixilated artifacted picture?

This crappy picture quality is not considered part of the disaster unfolding. The other thing the FCC promised broadcasters was that digital TV would be far less susceptible to interference than analog TV. This was, well I don’t want to say a big government department is a bunch of liars, so let’s use the college-professor term, and call it counterfactual. See, the MBAs and decision-makers never called up the analog engineers that run the transmitters or they would have learned how preposterous is the proposition that digital is always better. Analog can be very nice, indeed my computer is connected to my 47 inch Olevia 747i with an analog VGA cable and the 1080p picture is perfect.

The problem with digital transmission is manifold. First, many stations are changing transmission frequencies. One “feature” of DTV is that the station number you see on your TV set has absolutely no relationship to the real frequency that the station is broadcasting on. Can you tell software people were allowed on the “committee”? So channel 7.1 is really on UHF frequency 24 instead of VHF frequency 7. After February 17, 2009, channel 7.1 will stop transmitting on UHF 24 and go back to using frequency band VHF 7. That should be fun. Many broadcasters are fighting this, preferring to keep the crappy reception they have rather than move their digital broadcast back to VHF. The reason all this frequency switching is going on was to allow digital broadcast before the analog TV is banned, but there is another subtext. The phone companies are begging the FCC for spectrum that was occupied by the TV stations. The FCC has already pushed all the UHF stations off channels 69 to 83 and auctioned the bandwidth for 19 billion dollars. At one time the phone companies as well as data transmission coalitions like Google and Intel also craved the lower TV frequencies. The VHF frequencies are lower so they punch through walls very well. Not only that, the lower the frequency, the less power it takes to broadcast. So the brown envelopes were flying under the table and the phone companies the data companies were all licking their chops hoping to get a new slice of bandwidth. Finally some rich privileged CEO actually managed to talk to an analog engineer and learned that channel VHF 2 is broadcast on 55 MHz and you would need a giant antenna, just like the one on top of your house in order to receive it. So they stopped craving the VHF band for data and phone service, since people are pretty much inured to paying rapacious rates only for mobile communications and a 6-foot antenna does not look too stylish on your Treo.

So now the FCC will order TV stations to move their station back to VHF, but near as I can see, that is only if the station was on upper VHF, channels 7 to 13. The FM radio stations are in between the two TV VHF bands. Here in Sunnyvale, channel 2.1 will change from UHF 56 to UHF 44. Analog station UHF 44 will go dark and its digital station 44.1 will stay on UHF 45. After Feb 17 2009, analog VHF 2 will go dark. Whew. Channel 4.1 will go from UHF 57 to UHF 38. Channel 5.1 will just say on UHF 29. Can you see why TV engineers are terrified? All of a sudden a station like channel 44.1 will keep broadcasting on UHF 45 but instead of analog 44 next door they will have digital channel 2.1 broadcasting in UHF 44. What the RF lobes and sidebands and multipath will do is anyone’s guess.

Like I said, this whole fiasco only effects 50 million people and most of them are poor or live in rural areas so I guess as a society, we figure it is OK to screw them. Merry Christmas. The broadcasters are the big losers, but they were the ones whose greed let them be deluded into thinking they can broadcast 5 channels on the bandwidth of one analog station with no impact in quality. If you are like me, you do electronics consulting to all your non-technical friends. So get ready to dish out the grim advice. People in fringe rural areas or multipath urban areas will need an external high-gain antenna on a rotator. And it has to be mounted way up high, even if they live in a condo or apartment. The cable and satellite people love this disaster since they know a lot of people will just give up and sign up for cable and satellite. Be aware there are federal laws that allow anyone to put up an antenna anywhere, despite condo associations or anything else. That was due to pressure from the satellite gang, but it helps broadcast people nevertheless.

Another important fact is that signal boosters or beam-head amplifiers will not improve the reception unless you have a very long run of coax cable to your set. See, the RF transistors in a modern TV set or converter box are so good that they can pull in stations all the way down to the noise level of the ambient world. So if you put a signal booster in the line all you are doing is adding noise to the signal, so your TV has an even poorer chance of seeing a small signal. Sure you made the signals bigger, but you also raised the noise floor. The TV engineer that wrote me pointed out that saturating the RF front end is a big problem, so the other problem with signal boosters is that they will boost strong signals so much that it overloads the RF transistor in the TV. That is why boosters are meant only to compensate for long coax cables. The long cable will attenuate the strong signals as well as the week ones, and yes, a booster might bring the small signals up enough for the TV to demodulate, but it always adds noise. So weak stations will be wiped out by the noise added. Gee isn’t RF engineering fun? See why those RF folks make so much money?

OK, what else? Well, friends tell me not to put an antenna on the roof, it attracts lighting. So pour a couple of yards of concrete and put up a tower, but very near the TV so the cable is not too long. Be sure to put up a rotator. Some of my RF-savvy buddies have complex schemes where you have separate UHF and VHF antennas, and it will help to have redesigned VHF antennas that are optimized to receive only the high-band VHF stations. This will require shorter legs and closer spacing on the VHF part of the antenna. Be sure that you have the UHF antenna mounted with the right polarization, and my pals prefer Yagi types rather than the screen-door bowtie types.

You can bring your UHF stations in on a separate Yagi antenna like this and mix it with the VHF. It would have been much better if the FCC did not move the upper VHF stations back to VHF after Feb 17 2009. Unfortunately they sold off channels 69 to 83 to the phone companies so there were not enough UHF stations to go around anymore.

My friends don’t like these bow-tie style antennas for UHF TV. Be aware that there need be nothing different about the antenna due to DTV or HDTV. The RF is on the same bands and the different modulation does not mean that any type of antenna works better or worse than before February 17, 2009.

OK, so put up an antenna outside 30 feet up and add a rotator. Put it in close enough to the TV so you don’t have to lower the signal-to-noise ratio with a signal booster. If this does not work you will need to try separate UHF and VHF antennas. Oh, everybody tells me that your antenna should have an FM radio station notch filter (or FM trap) so that those stations don’t overwhelm your TV RF front end. So ultimately you could end up with three antennas, a VHF rebuilt for 7-13, a UHF rebuilt to ignore 69-83, and a FM radio antenna optimized from 87.5 to 108 MHz. Of course, the cool person would have all of them on separate rotators. Once again, some bullet points so you can help you friends:

• The digital television switchover only affects people that use antennas to get TV.
• If you have a TV with an ATSC tuner instead of an NTSC tuner, you can already receive digital TV. You may have a different RF inputs on the back of the TV or one RF connector might receive both analog and digital stations.
• If you want to make an old NTSC TV receive digital TV you have to buy a converter box or switch to cable or satellite service that uses a set-top box.
• When you put the converter box on the TV you still need your antenna. The digital TV does not come out of the converter box. The converter box changes the digital TV signals coming in on your antenna to analog TV signals that your TV can display.
• The converter box will have its own remote, you no longer need to tune the analog NTSC TV, just like you had a VHS player hooked up. You just set the TV to channel 3 or 4. Some boxes also can connect to composite or component TV inputs.
• The converter boxes can get a TV guide from over the air but it takes a while for that to come in.
• The same channel, say 7, becomes 7.1 and 7.2 and 7.3. Stations can put up to 5 programs in one channel.
• The actual frequencies have nothing to do with the number of the station. The transmitter may have moved, so stations that came in OK may fail after February 17, 2009.
• Digital TV does not have snow or fuzzy reception. It ether works or it doesn’t. In weak signal areas or places with interference the picture and sound will just go away for a few seconds.
• You may need an external antenna for your TV, or you may have to raise you existing external TV antenna higher. You may have to install a rotator on your antenna to receive the weaker digital TV signals.
• It is against the law for your apartment house or homeowners association to prevent you from mounting an external antenna.
• Low-power stations can still use analog modulation so your converter box should have a pass-through or your TV should have an NTSC tuner as well as the ATSC tuner.
• Canadian stations make the transition in August 2011 so this only affects Canadians that want to watch good television.
• This is all part of a giant conspiracy from the FCC, the cell phone companies, the satellite TV companies, and the cable companies. They want to screw you to make more money. Try as hard as you can to get your antenna working before giving up and buying cable TV or satellite TV service.

But we are not done yet, you cable people get to be screwed, too, however you should be used to it if you have been paying for cable all these years. See, cable companies want to move your local channels off the analog band on the cable to a digital band. They will call it an upgrade and then charge you more. This is a completely separate shafting than digital TV. They were going to do it on February 17, 2009 to con you into thinking that they had no choice, but its all a plan to bump you into a digital reception tier so the cable companies can charge you more. Analog guru Paul Grohe elaborates:

I figured this would happen as soon as OTA [over the air] analog dies...

The CableCo can get 5 or more standard def digital channels inside a 6MHz "analog" channel. To get more channel capacity - they digitize an analog OTA channel into a digital channel. Then they can sqwoosh more channels into their 600-800-1000 MHz bandwidth system.

Come February, when OTA analog is dead - why should the cable companies continue carrying the inefficient 6MHz analog signals on their closed system??? Then they can provide more channels (ie: more PPV [pay-per-view]), and ding you an extra $5-10 per month for "digital" service tier as well as a "digital" cable box rental (which also throw ad's at you).

If the CableCo plays fair, the "digital" signals will be "in the clear" (unscrambled) and digital cable ready TV's (QAM [quadrature amplitude modulation] tuners) can receive the digital signals without a CableCo supplied cable box (just like the analog channels now).

This is one of the reasons I went to satellite years ago. AT&T at the time was moving what are considered basic cable stations (Discovery, A&E, Fox, etc) to the digital tier from the "extended-Basic" analog tier - which meant another $20 per month for "digital" service if you wanted those channels back.

I figured if I needed a box on the TV to get the channels - then it did not matter if it was a cable or satellite box - so I went with satellite for $30/mo less and more channels.

So the New York Times article I linked to at the beginning of this blog says that the cable companies are postponing their transition to a month later. They liked being associated with something that would make you think it was mandatory from the FCC, but now that the DTV transition is turning into a disaster the cable companies are trying to distance themselves from the whole mess and they will just screw you in a separate fiasco like they have for the past six decades.

Now I have ranted about how the FCC is no longer a technical organization but a political one. But remember that the bulk of the FCC, the engineers and technical people, are the same great folks that have worried about interference and universal access since 1934. The political part of the FCC has recently gone on a supposed “free market” stance, but it is not really free market, it is mercantilism, where the companies with the best lobbyists and biggest budgets get to roll over the people. Adam Smith discredited mercantilism in 1776 with his book The Wealth of Nations. I guess we haven’t learned yet. If the FCC was really about promoting the free market they would sell the bandwidth and give spectrum property rights, as opposed to selling permission to use the bandwidth, which, as the broadcasters just learned, include the privilege to get screwed whenever the cell phone, cable and data companies come in with bigger brown envelopes stuffed with cash. I will elaborate on this in a subsequent post on the white-space proposal.