Philly area WPVI / 6ABC issues illustrated

I thought I'd do a little more documenting of the trouble specifically with receiving channel 6 (ABC/WPVI) out of Philadelphia in my area (about 25 miles East of Philly). I'm sure that anybody who read my last post would probably have difficulty imagining exactly what the problem may look like. Well, now I've taken photos and am posting them as visual aids. If you want to skip a lot of nonsense and just skip ahead to them feel free to scroll on down to the end of this entry. (And honestly, you're probably better off to just going ahead and doing that. Can't say I didn’t warn you.)

First let's recap the analog to digital TV transition situation and provide just a few technical details to set the scene...

To receive digital TV transmissions using a rooftop antenna I had to disconnect it from my TV and insert a converter box in between. (I'll just use the shorthand of "c-box" from here on out.) So the antenna now connects to the c-box and the c-box connects to the TV in that order.

The c-box receives the digital broadcast signals through the antenna and converts them to an analog signal for display on my old pre-digital era TV. As is usual for such video accessory boxes, I can select either channel 3 or 4 as the output channel to the TV, i.e. the specific analog channel which the c-box will convert the digital signal to for display. Doesn’t matter which I choose, but I happen to have it set for channel 3.

So the TV is always tuned to channel 3 now in this glorious digital age. I then must tune the c-box to whatever digital broadcast channel I actually want to watch. No matter what channel that is the digital signal gets converted to and output on analog channel 3 to the TV.

So far that's all plain and simple enough, right? Right.

Now, shrouded in mystery from way back in the time before digital broadcast TV—well, OK, just last week—my particular area has long been susceptible to seemingly random interference in the low VHF band from 2 to 6. Channels 2, 4, and 5 were unused locally, but channel 3 was CBS/KYW and channel 6 was ABC/WPVI, both broadcast out of Philly. And both of those channels would often show horrendous static lines throughout the picture. Some nights the interference would be there, other nights no interference whatsoever. Sometimes the interference would go away all at once, possibly to return later, or it could sometimes gradually lessen or increase over a period of time. Sound would be affected too in that along with the soundtrack, dialogue, whatever, you would also hear a lot of crackling static-y noise.

As bad as it was, though, you would still be able to watch a program and follow what was happening. Yes, it was very annoying, but always at least watchable if you were interested enough in the program to begin with.

So hold that thought right there: "Analog channels 3 and 6 were susceptible to massive localized interference at times."

With the changeover from stations broadcasting in analog to broadcasting in digital most stations across the country now broadcast using UHF channels (14-69) which are much less prone to potential local interference. Let me point out also that "analog" or "digital" is really just a matter of signal format or encoding. The channel a station’s source transmitter is broadcasting a signal on doesn’t care whether it’s an analog or digital signal being broadcast—the channel itself is still the same old channel (or frequency if you prefer) that it always was. To illustrate using the specific case under discussion, channel 6 is still the same channel 6 (i.e. the same broadcast frequency) whether the signal being broadcast is encoded as analog (prior to 12:15 PM on June 12th) or digital (after 12:15 PM on June 12th).

So channels 3 and 6 often had analog reception problems due to the known (though untraced) local (which always seemed to have no discernible pattern as to time of day or which days or even duration of the effect).

The thing is now, though, digital signals carry a lot more encoded information and are therefore not nearly as forgiving as analog signals were. If there is any sort of significant interference with an incoming digital signal it can cause the program you’re watching to either pixelate beyond recognition (losing audio as well) or drop out to a simple "no signal" black screen as the display. Either way it's not like you have a clue what’s really happening on screen.

Now let's go back to that thought you were holding... (You are still holding it, right? Good.) What do you think would happen to a digitally encoded broadcast on channel 3 or 6 if they continued broadcasting on those same actual channels in the digital age? That’s right, they'd be susceptible to the exact same local interference and that would cause the program to be quite literally unwatchable (not just merely terribly annoying to watch as in analog).

Channel 3 avoided this issue because their digital signal is not being broadcast on VHF channel 3, but on UHF channel 26 instead. That fact is transparent to the c-box user because one still only has to tune it to channel 3 (as everyone is already used to doing) and the c-box magically (somehow) knows to find the channel 3 signal on channel 26. The station still IDs itself as KYW/CBS3, not CBS26.

Channel 6, on the other hand, for some reason chose (or was assigned by the FCC) to remain on VHF channel 6 with their digital broadcasts. Prior to the DTV transition they had been broadcasting their analog signal on channel 6 (as always since the dawn of TV itself) and their digital signal was on UHF channel 64. As I’ve already noted throughout analog channel 6 was often messed up by the interference, but the digital channel 6—being way up the UHF band—was clear as the proverbial bell. And now that the analog signal has gone away forever and the digital signal has shifted over to VHF channel 6, well, I just never know if I'll be able to watch an ABC program or not. Depends on the whims of whatever the heck continues to cause all this local interference.

So as of June 12th all the old analog broadcasts are gone and where those channels used to be they now just show white noise on the TV screen... except channel 3! It turns out that on analog channel 3 there is now a continuous looping broadcast of a public service program about the DTV changeover. It features people explaining what folks out there in TV land must do if they want to be able to watch their favorite TV programs again, how to hook up a c-box, and where/how to order c-box coupons. The information is presented in both English and Spanish. I assume that in other major TV markets there is likely a similar program (actually, quite possibly the same exact one I would think) being aired on some particular analog channel.

Tonight I've been unable to watch channel 6. (Not that I actually wanted to, but I’ve been trying to check on the situation every now and then just out of curiosity.) I knew beyond any doubt that the reason had to be due to the intereference being heavy tonight. I then realized that since such intereference always affected both channels 3 and 6 equally, I could just tune my TV to VHF channel 3 and actually look at the public service program being aired there to actually confirm that the interference was indeed the present and heavy—which I did. I then decided to take pictures to illustrate.

The first three images below show the effects of the local interference on analog reception (on actual channel 3 during the public service program all about the DTV transition). What you see is exactly how programs on 3 and 6 periodically appeared in the analog days, with those static lines running horiczontally through the picture. Also, the lines tend to crawl slowly up the screen and then when they reach the top, switch down to the bottom and continue the upward crawl again.

The last three images show the effects of the exact same interference on digital reception, specifically just before 10 o'clock during ABC's airing of Samantha Who? on channel 6. And bear in mind that those are some of the more decipherable images! There’s absolutely no audio to go with those weird mish-mash images. If a scene is relatively still, not much going on, not much movement by the actors on screen, then an image can once in a while become halfway identifiable as Christina Applegate. When the scene goes to something with a lot of movement or rapid changing of camera angles/scenes, that's when it visually becomes completely unidentifiable, looking more like a Jackson Pollack painting. And as always, just click'em to view'em full size.


Effects of local intereference on ANALOG signals...

       

Note that in the middle image above I snapped the shot while also displaying the channel to which the TV is tuned with the c-box in fact turned off. I've labelled channel 3 on the TV as "DTV" just because that's what I'll be watching there (digital TV) from now on. But for the purpose of this little exercise in photo documenting things I'm actually NOT watching DTV, but the simple analog public service broadcast that's going out to all analog viewers via VHF channel 3.

I wasn't paying a bit of attention to what was actually on the screen when I snapped these pics, so the fact that that middle one turned out mildly amusing (or at least ironic) was completely by sheer luck.


Effects of local interference on DIGITAL signals...

       
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P.S. I checked again at 12:15 AM (Jimmy Kimmel Live) and 1:45 AM (rerun of The Oprah Winfrey Show from the afternoon) and I'm still getting nothing but "paint spatters," if that. I'm hoping that Saturday nights at 10 for the next four weeks will be fine as ABC is burning off the last four episodes of Eli Stone, a show I liked a lot during its brief two year run.
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P.P.S. It's now 10 AM the next day and the static is still clinging to that signal. I'm still hoping it will clear up by tonight at 10 PM for Eli Stone, but I won't be surprised if it doesn't either.

If only there were a pattern to the timing of the interference then maybe I could at least have an idea of when it would be a problem and not get my hopes up for watching a program on channel 6. Better yet, any detectable pattern might also help pinpoint the source of the interference so somethng could actually be done about it. The only thing I know for a fact is that the source is not anything in my home because the whole street has always been affected by it. It's something emanating somehow between here and Philly that does it, but danged if I have a clue...

My best bet (well, only bet as far as I can tell, actually) is just to hope that channel 6 in cooperation with the FCC can come up with a timely workable solution from their end which will negate or overpower all such interference, either by boosting their digital signal strength on VHF channel 6 or by moving their digital broadcast to a whole other frequency, prefereably in the UHF band.