Saturday, March 08, 2008

Geek Mode Enabled

My previous post about Analog TV, Digital TV and Its Wonders (yes, that's three categories) has prompted a number of responses, including some information a less-than-informational nature.

This is about par for the course. The newspapers have been, shall we say, not all that helpful, while TV station News departments have been largely ignoring the whole thing (ew, ick, Engineering) in the hope it would go away.

The Basics:
First off, yes, analog TV will (mostly) shut down in February 2009. (The little low-power stations have, per the most recent word, until 2012 to make the switch to digital).

Yes, that means grand-dad's fridge-sized RCA with the big, big 12" screen won't be able to pick up stations, no more than it ever was able to tune in UHF.... And there's the rub. As one commenter has already discovered, converter boxes are coming on the market. They hook up between your rabbit ears or outside antenna and the antenna input or audio-video inputs of your present TV and tune in all flavors of HDTV, converting it down to standard-resolution; while you won't get any better a picture than your TV is presently capable of giving you, you will get everything it can do, picture quality as good as you're getting from a DVD player. You're probably not getting a picture that good over the air or via analog cable right now.

So you will have to buy something to keep on gettin' free TV, and you can thank the Grand Alliance[1] of set makers, computer companies and film studios for that; but it is not a whole new overpriced Red Chinese, er, expensive, imported, um, somewhat to the high end of affordable but nifty HDTV set.

In fact, with a converter, you can even keep on recording things in 525-line standard-definition.[2] Just put the converter box ahead of your VCR or DVD recorder or video server.

Cable and satellite TV companies will also still be pumping out analog-compatible TV to to the paying customers -- also to that lowlife across the alley who hooked up his own, at least 'til they find him out.

Stations were assigned DTV power levels that gave them coverage equal to their analog coverage. In practice, since a digital TV signal is either great or gone -- and ATSC is way more so than the encoding used for satellite TV -- this means the "fringe areas" are now gonna get decent pictures.

Spectral Recovery:
Yes, the FCC will begin saving ghosts.... Or not. And the DTV/HDTV signals are exactly as wide, per channel, as the old analog ones. Oh, just barely; we have to jump up an' down on 'em to get them to fit and even at that, part of my job consists of goin' around every so often an' givin' the stuff that stuffs it all down a good, solid whack wherever it's bulging.

Howsomever, we can do a cute trick with DTV that we could not do with analog. While a cable company can use all or most the channels, 2-3-4-5-6-7-8-9-10-11-12-13-14-15-16....99999 by dint of havin' it all in one wire where they can fuss with it[3] but channel assignment for over-the-air analog TV is one of the very darkest of Dark Arts; this is why you will often find similar groupings of channel assignments in different cities. All those "extra" channels are needed so the stations can be assigned channels in such a way as to not interfere with one another (at least on paper). This is not true of DTV; those channels can be stacked up side by side by side, without interference.

Can be and are. Some bright lad at the Grand Alliance put a bug in the ear of some bright lad at the FCC, and they worked out there were a whole lot of channels on the UHF end nobody was going to need. So no new channels were assigned up there and the stations that already were there got told not to leave anything behind when they packed up for their new DTV channels. The vacated space was auctioned off for public-safety and other two-way radio uses, including some data comms. The original plan was to clean out not only the top end of UHF but the very bottom of VHF[5] as well. This foundered on two things: low-band VHF stations (2-6) have been groovin' for years on havin' signals that could be picked up from Big City to Bugtussle (and, when the wind is right, in Far Forn Parts) , which they did not care to give up; while, conversely, no two-way user was seriously interested in such low frequencies.

So the Feds ended up "owning" (?!!!) some shiny-new spectrum, which they promptly put to work hailin' traffic on the nearest street corner. 'Course, it won't have any place to go until 2009 and the cars are backin' up, so you can see that the odds of that Feb '09 date gettin' pushed back or set aside are, well, as slim as a crack whore.

In Summation:

I. DTV picture quality and sound are really good. Even with a converter box ahead of your old TV, you'll see some improvement. (If you have really, really bad ghosting, there is a slight chance you won't see nothin' -- see, it's either there and good, or it's gone. That's digital for ya).

II. Save your Steam-Powered TVs. They can still be made to work. If you have cable or satellite, you're home free.

III. Wave bye-bye to the upper UHF channels. There was never anything good there anyway. Besides, it'll still be on the air, just at a lower number. Though your TV may lie to you about it.

IV. This was not the TV stations' idea. It wasn't even thunk up by the networks. On the other hand, the TV set market was pretty much saturated and the TeeVees were lastin' a long, long time. Something that would make people go buy new tellyvisions, h'mmm, cui bono? Yeah. Them. The spectrum sell-off was just the bait the Feds lunged for. (Look for some "buyer's remorse" posturing in Congress as the deadline approaches. Also lines like, "technological disenfranchisement," which translates into, "free TVs or converters for the people in my district whose votes I am courting." Your tax dollars at work).
1. I'm pretty sure they helped start WW I, too.
2. HDTV standards counterpart in resolution and screen shape to what we get from 525-line analog is called, confusingly, 480i; each number refers to the number of horizontal lines per image but the older term uses the total number of 'em including the ones that are working behind the scenes to keep everything in sync while the newer term just uses the number of lines actually displayed. The "i" tells us it's knitting the picture like fancy socks, alternately sending the interlaced odd-numbered and even-numbered lines to fool your eye all the better. Other common resolutions are 720p ("progressive," all the lines of the picture one after another in order in the manner of a computer monitor), 1080i, and -- not over the air -- 1080p. Nobody could figure out how to stuff all of 1080p in the teeny little box we have to cram the pix into to get them through the air. Or at least they couldn't a decade ago.
3. They also cheat -- starting with 14, none of them are on the same frequencies as the over-the-air channels of the same number. This can lead to big fun for radio hams and other users of two-way radio when the cable system leaks signals. Which they do.
4. Most every other station has the option, come 02-2009, to stay on their DTV channel or return to their old channel in their coat of many digital colors -- and the software is set up to lull your DTV set into believing they've been on the same channel all along.
5. This terminology may irk English- or 'Strine-speaking overseas readers, who are used to thinking of TV channels as not being so very much in one "band" or another and get their local high-fidelity, frequency-modulation stereo radio signals on VHF. US terminology differs. It's all part of the fun, really.


Breda said...

hmm...all this and there's still nothing good to watch.

Roberta X said...

Precisely. Paladin was shot in black and white on equipment any crew from the early days of sound-on-film talkies could have used and merely in the use of lighting and sets to tell the story, it's still miles ahead of anything you'll find on TV now. Add in the writing, and, well.... Who needs the new stuff?

dneylon said...

nice summation Roberta. Did you mention that the gov'mint's giving out vouchers to buy the converter boxes with?

Roberta X said...

I did not. I do not approve of them. Rob your neighbors to feed your habit? Not my sort of thing and I shan't encourage it. Better you should maybe read a book.

Jayson said...

I put people who say, "Here's nothing good on TV" in with the camp that says, "There is no good new music".

Both statements are wrong.

Like anything else in life, you have to put in a little work. "Battlestar Galactica" is great. "Weeds" is great. "Burn Notice" isn't everyone's cup of tea, but it's fun.

If you disagree with me, then the terrorists have won.

Roberta X said...

Point taken.

Mark said...

*jaw sags to bellybutton level*


I ... I thought I was the only one left. Have you checked out the clipping levels on YUV colourspace for the MPEG4 stream they're generally shipping as 1080i? Really, it's barely 6bpc - nothing like "true" 24 bit colour. Gh0d help 'em when they start getting a demand for HDRI HD signals, they're gonna shit pink.

Carteach0 said...

And you know what? You know what? You know what?

I think I kinda understand that now....


HTRN said...

Nothing good on the higher UHF stations?

But, but, but.. WNJN(Channel 50)runs 4 hours of cooking shows every Sunday!

Turk Turon said...


Roberta X said...

Mark, I'm about half a video geek when it comes to DTV; I'm better at analog. I'm a lot more of an RF geek, jackleg electrician and general artificer, which is howcome I'm fixing stardrives for a livin'. All that high-power RF, you see. :)

In the the trenches, we're spending a lot of time explaining to managers outside the artistic and tech departments that upconverted 16x9 standard-def is, in fact, not actually HD. It's all uphill.

Roberta X said...

HTRN: izza joke.

phlegmfatale said...

I love it when you talk nerdy to us.

HTRN said...

Roberta: I know, hence the response. :)

You wimminz just can't understand the subtlety of my highly developed humor ;)

Mark said...

Blech. I get that a bunch, too. I've gotta admit, HD just isn't as much *fun* as analogue signals - I kinda miss toting around genlocks and black-burst generators in studios. These days, there's so little to it - ensure signal legality, upload to the MUX and that's about it. Not even any safe areas to play fun games with, or overscan to dabble with.

Still, it's a lot cheaper not actually needing specialised equipment to assemble HDTV broadcast material - yer basic pee see is plenty. Haven't even used my edit deck in over a year, I just bung things around on the workstation.

Can't help but feel that a little bit o'the magic's gone, though.

Turk Turon said...

Remember color-framing? And "colour-framing" was even worse! Eight fields!? What were they thinking?
Remember drop-frame time-code? PAL doesn't have that; one of the pleasures of editing in PAL.

Roberta X said...

Turk -- remember "3-2 pulldown?" --I always thought it was a gym-class prank boys played on one another, but noooooo, it's how they worked out playing 24 frame-per-second film on 30 fps TV. (wiki sez) This is what makes the distinctive, machine-pistol-like "stutter" of an NTSC telecine.

Lorimor said...

Paladin Palidin where do you roam?

Old Grouch said...

"it's how they worked out playing 24 frame-per-second film on 30 fps TV."

Which is one reason the original Todd-AO 70mm film standard (think "Around the World In 80 Days") ran at... 30 FPS. Problem was, they couldn't figure out an easy way to down-convert the 30 FPS film to standard theater's 24 FPS (dropping every 6th frame generated nasty artifacts), so the studio planned a release in Todd-AO and to regular theaters, they had to simultaneously shoot things in both formats. Needless to say, didn't continue very long.

Then NTSC came along with its 29.996 (or whatever) frame rate, and everybody threw their hands up.

jed said...

Well, my bad, I guess. I know I read that stuff about channel width someplace -- hey, it was on the internet, so it had to be right, right?

I think it's funny that we use frequency numbers for radio, but channel numbers for TV. Maybe it's just too much to expect Bubba in the La-Z-Boy to know that Channel 4 is whatever it is, and find it again if it moves. Really, with auto-scanning tuners, is that a big deal? But I didn't have any trouble when KCFR moved from 90.1 FM to 1340 AM, and KVOD got moved from wherever they were to 90.1 (where I didn't have any trouble finding them). I like it when I can look around in at and find a channel 9.1 in both the VHF and UHF bands.

jed said...

Well, you got me curious, so I hit the web some more and found info about how the broadcasters can use compression to stuff standard definition NTSC into a digital broadcast using less spectrum, so they can subdivide their channel if they want -- say into 1 NTSC channel, and 1 (or more, depending on what level of HD?) HD channel, or use the whole thing for 1 HD broadcast, which is where things such as channel 9.1 come from.

At least, that's what this page says.

Roberta X said...

Jed, channel numbers were used to simplify tuning; there are, in fact, "channel numbers" for US radio broadcasting, too, but you'll rarely see them outside FCC documents.

As for narrower channels, I suspect some journalist concatenated the DTV transition with another one presently happening behind the scenes: in yet another hey-look-we-can-sell-this move, the transmission method and frqency assignments in the (approx) 2 GHz range used by TV stations for local, point-to-point live-on-the-scene apps ("ENG") is in the process of changing to digital (though not the same digital as the signal we send the home viewer) and getting narrower. Some celphone outfit bought the freqs that will be left over, even though the price included buying all-new ENG transmitters, receivers and related equipment for every TV station in the US. It's going, ummm, slowly, at least a year behind schedule and a third done.

jed said...

Well, the interesting side effect of the channel numbers finding their way onto the tv dial (yes, I do remember tuning the tv by walking across the room and turning a knob), is that the channel number came to be a brand name. Much less so with radio. For example I still often hear people talking about radio stations by their call letters, but it's far less common (approaching zero) for tv stations.

But of course, from a business and marketing point of view, making your channel number part of your brand name only makes sense, and there are plenty of examples of radio stations making their frequency part of their brand as well. But it isn't necessary, as we can see from what happened with cable, as in CNN, FoxNews, etc. PSIP (if I'm understanding it) could make possible a complete dissociation between channel assignment and brand, but there's too much inertia for that too happen -- at least while I'm still above ground.

Roberta X said...

Jed, in re your latest, yes, TV stations can trade resolution for number of program streams, the upper limit being the bitrate of the 6-MHz-wide ATSC TV channel. One HDTV at 1080i + 1 SD at 480i is a popular choice. Or one 720p and a couple of 480s, and so on. (How about several camera feeds for a baseball game and you pick your own view? They can do it now).

Better tech means we can pack way more stuff into 6 MHz than we could in 1953, when compatible color came along. But it's still the same width channel and after the transition is over, TV stations will have exactly as fat a pipe into you eyes as they did before. They're just able to pump more stuff down it.

End result, no extra spectrum from that change.

Roberta X said...

(Make that "your latest but one." You're too quick for me!)

jed said...

Oh, I think you're much quicker than I. :)

As far as multi-angle broadcasts of the same thing, it reminds me of the scene in "The Man Who Fell to Earth" where David Bowie is watching about a dozen tv's at the same time. And of the professor I used to know who had I think 5 tv's going at once to watch sports. Gaaaaaaaack.

And Videodrome too (speaking of pumping things into your eyes).

Turk Turon said...

I will not miss the arcane but admittedly ingenious method used to add color to the black-and-white picture in the 1950s. By adding a color subcarrier, slightly shifting the frame rate from 30 to 29.97, locking the horizontal frequency to the new subcarrier and making the subcarrier an odd multiple of the horizontal frequency (I think that's close), they were able to interleave the color sidebands among the monochrome sidebands and pack a color signal inside a black-and-white signal. So people with B&W TVs could continue to receive TV signals, but in black-and-white, of course.

Word verification: harmpfhy

Mark said...

I saw a horrible case-in-point of the weakness of digital systems this very evening, watching Terminator 3. It had obviously been telecine'd (pardon me, Queen's English) using a digital processor, as there was a constant "focus shift" effect, where the frame has a ghosted stagger once a second or thereabouts (there's a beat frequency involved) from brute-force interpolating 24fps to 25fps - an analogue transfer from celluloid to BetaSP would have been significantly more graceful - but more complex, require higher-priced pseudo-obsolescent kit, and someone who'd read more than the Adobe Premiere manual to do.

Looks like "Writing good TV" and "Making good TV" aren't the only lost arts - or at least those written off as "irrelevant".


Lorimor said...

Egads!! I haven't heard this much RF geektalk since DD963 Comm package school waaayyy back in '78.

One dark and stormy night in Pascagoula MS a lanky young ET3 keyed up a 10KW xmitter on children's band channel 19 in a moderately successful attempt to entertain the Shrimpers out on the Gulf.

Mark said...


I shan't miss it too much, either - I do prefer to concentrate on "doing pretty" than "preserving pretty after it's been folded, spindled, mutilated, pulverised, mangled, mauled, squirted to the bird, downsquirted to a MUX through atmo interference both ways, recompressed, retransmitted to local relays and rebroadcast having been gently massaged with the equivalent of a steak tenderizer and shoved into pots at a ratio no smaller than one pint to one point five half-pint pots."

But it was pretty gorram clever :D

Also, comforting to know I'm not the only one eternally searching for meaning in the word verification. I might be barking mad, but now I know I'm not the only one.

Turk Turon said...

Yes, welcome! There are several of us here who are barking mad.

Roberta X said...

Mark, per Wikipedia: 'PAL material in which 2:2:2:2:2:2:2:2:2:2:2:3 pulldown has been applied, suffers from a similar lack of smoothness, though this effect is not usually called “telecine judder”. Effectively, every 12th film frame is displayed for the duration of 3 PAL fields (60 milliseconds), whereas the other 11 frames are all displayed for the duration of 2 PAL fields (40 milliseconds). This causes a slight “hiccup” in the video about twice a second.'

I belive that could make one's head hurt.

The digital artifact that bothers me the most is "floating face." US satellite provider DirecTV can have quite a lot of it, especially when bandwidth needs are pushing the limit. It's migrainical!

Anonymous said...

Roberta, thanks for the summary.. no idea how on earth I landed here.. from some gun message board following links.. but I do appreciate the info on HDTV. No fan of it myself.. but since we have satellite here.. we are going to be OK.

BTW nice to see a female ham out many of us guys in the hobby :) AND one that enjoys shooting too! Nice blog.. 73

Mark said...

Another vaguely amusing thing was that having picked up my brownish-coloured coat watching Firefly from PAL DVDs, everyone's voice sounded a noticable smidge deeper in the movie Serenity - 'cause they hadn't been sped up to match 25FPS from 30.

You'd think we'd be able to do graceful conversions these days - or at least pick one format and stick to the damn thing.

Roberta X said...

Anon, welcome and thnak you for your kind words!

Mark -- sped up from film's 24 fps to 25, I suspect. Firefly's still good stuff, even a little fast. When I bought my most recent motorcycle jacket (a kind of fantasy-military-lookin' thing), it was available in blue, black and brown. I had to buy the brown version, of course!

J.R.Shirley said...

I, um, actually found that rather interesting.

I was horribly afraid the movie Weeds- which is probably tied with Wishmaster as the worst movie of all time- was being referenced, but I see there's a TV show of the same name.