# NBC OTA Problems v2.0



## PLHOG (Oct 10, 2006)

Hi:

Having gotten past the reboots when viewing the NBC local affiliate off-the-air signal (WCMH, Columbus OH) , we have the return of the problem of image freezes and frame skips. After a few seconds, we get the 739-Signal lost error screen. The ABC and CBS stations come in great OTA, as did the NBC station for most of the previous programming season. Then a few weeks back, the freezes/skips returned. 

We saw this with the NBC OTA signal once before, I complained to the chief engineer and the station, and soon afterward the problem went away. Now it's back. I've sent another complaint to the chief engineer, and we'll see what happens.

When the crash thing was happening, we noted that the problem seemed to be more noticable, if not exclusive to, when tuned to NBC affiliates. Dallas and Columbus seemed to be among the worst. The WCMH chief engineer told me that her station and the Dallas station used the same encoders. It seemed like the problem went away about the same time in both cities.

We're in flat country and have a line-of-sight path to the NBC tower, which is less than 10 miles away. Our OTA antenna is roof mounted, but signal strength for the NBC stations is around 90. The other locals peg at 100.

So are any of you in Dallas seeing this freeze/skip thing now? Anyone anywhere else? Is it on your NBC station when viewing OTA? This doesn't feel like an encoder problem though, more like something with the transmitter end of things.

It was a real drag to have to watch the US Open in SD analog...

Thanks


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## PLHOG (Oct 10, 2006)

The chief engineer at WCMH sent me an email saying that Dish has a software fix that deals with digital channel 14, which is where the WCMH digital signal is carried. Anyone know about this?


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## tferrio (Sep 6, 2006)

I am in Dallas and have not seen the NBC OTA lockup problem for some time. The improvement did not seem to coincide with a 942 firmware update so the idea that the station did something seems justified.

If there is some remaining freeze/skip issue it has not been bad enough to notice.

Tom


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## yottabit (Jan 2, 2008)

I have a 942 and after moving and stopping DishPause, my OTA channel ATSC 14 NBC local in Columbus skips out and finally I get the signal lost message, despite all other channels being in the 90-100 range, even without a preamp...

I e-mailed Debra (I think) at WCMH and she said she'd check into it, but I haven't heard anything else for over a month, and the problem persists... I know others have posted in another forum/site that they just upgraded to the 622 and problem solved, but I don't subscribe to any HD package now and don't want to pay that stupid "HD Enabling Fee" plus the upgrade cost.

Anyone have any more info?? 1+ years ago, before the move and new house and DishPause, that same channel came in just fine with a far lower signal strength...


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## PLHOG (Oct 10, 2006)

I got tired of the finger pointing, so gave up and ordered a 722 this week. With their current HD offers, and the fact that I already have HD service, the net upgrade cost was minimal and I get several new channels.

I'll be keeping my eye on the new AT&T offering that they can apparently pipe down DSL. My son-in-law is a tech for them, and when I said I was concerned that the video would get unacceptably compressed to put all those channels on DSL, he said the way the technology works is that the DSL had to carry only two video streams - the ones you were actually watching - and that the channel switching occurred upstream somewhere. Sounds promising.


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## yottabit (Jan 2, 2008)

Bah, not what I wanted to hear! heheh. My 942 has always worked flawlessly and I don't want to pay what would amount to significantly higher prices in order for me to upgrade...

The video over DSL thing sounds like it's just IPTV. And the transmitting of just the two channels you're actually watching (or one per tuner, etc.) is the same thing Time Warner Cable does for their iDemand (video-on-demand). You go to the PPV movie you want to watch and hit Play... not necessary to wait for the next timeslot to start. And you can pause, rewind, etc., and it's all done at the back office. At least for TWC's iDemand I have used at the in-laws' up in Findlay, the PQ was pretty bad, and the delay between hitting Pause or Rewind, etc., and it actually doing so was perhaps 1-3 seconds on average and was quite unnerving. Of course you could get used to it, but I didn't like it since I'm so used to the way everything works on my 942. Oh, and you would need a rather fast DSL pipe for this to work too...

According to the H.264 MPEG-4 High-10 Profile which is the most commonly used CODEC for MPEG-4 HD video, a full 1080i picture would require 40 Mbps! The fastest DSL is usually offered is 6-10 Mbps, and while I know there are some places that can get DSL in excess of 20 Mbps, I don't know if they're available in the US (I typically hear of these speeds from my Europeans friends and colleagues)... I could be wrong here, and of course we can always compress more to lower the bitrate (hey, even the OTA ATSC is compressed a LOT more than people realize; my buddy that is a TD for video production of HD sports programs says I wouldn't believe the difference of seeing a completely uncompressed/reduced HD feed right on the TV truck...)...

Anyway...


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## PLHOG (Oct 10, 2006)

Sounds like we have overlapping backgrounds. I own a piece of a company that makes digital signage. After 30 years in the technology side of an information services and data networking business (CompuServe), I had to learn all about computer-based video processing with this new outfit.

Once upon a time I got to see the rendering farm being used by DreamWorks while they were creating Shrek. It was a sizable array of SGI servers housed in the old Cray corporate computer center in Minneapolis, and hooked to the DreamWorks studios by an OC-3 or so. The guys there said it would take all night to render a couple of minutes of animation.

One of the things they had to figure out was how much motion to introduce knowing that eventually it had to be resolved to a constant 24fps rate. It was certainly possible for their physics engines etc to produce much more detail than could be represented.

Anyway, that conversation really helped me develop a mental model about video compression, and has consequently made me wary of what folks mean when they say "HD." I was an original VOOM subscriber, and can tell you that in general the HD channels on VOOM looked much better than DishHD, and I chalk it up to the compression (Voom was also encoded to MPEG4, while the Dish 942 operates on MPEG2). One of the reasons I decided to upgrade to the 722 is that it is supposed to be based on MPEG4 (but what compression settings? who knows...). We'll see what happens to the picture quality.

And I know what you mean about seeing the raw signal. I visited the ASTRA uplink facility in Luxembourg once, and they had a wall of monitors showing the raw feeds before being encoded for transmission to the satellites. This was pre-HD, just the European PAL format. Gorgeous picture.

I'll post a report when the 722 arrives. I got the UPS shipping confirmation today.


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## yottabit (Jan 2, 2008)

heheh, well despite appearances, my background is actually in data network, computer hardware, and long-haul fiber-optic transmission engineering... none of which is really TV- or video-related, but I also have a lot of techie friends, and of course some of them are in TV... 

Yeah I was an original VOOM subscriber too, and I couldn't believe how incredible the PQ was... for that matter, PBS HD was awfully nice OTA too before they started running their SD subchannels simultaneously with their HD subchannel... now I can't stand watching it because the bitrate is *far* too low and the pixellation is so pronounced it makes me dizzy!

When will we get VZ FIOS and HQ MPEG4 IPTV?  We need another alternative... TWC could actually compete if they would dump the analog portions of their bandwidth entirely... I mean hey, 2200 MHz of bandwidth, properly coded, and properly delivered (even IP would be okay), would devastate satellite and probably even one-up the lousy 6 MHz of OTA bandwidth per channel allocated by the FCC for ATSC channels (full-quality HD requires 22 MHz, by the way)...

I digress...


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## PLHOG (Oct 10, 2006)

I installed the 722 over the weekend. Easy job - just moved the connections from the 942 to the 722 and powered it up. Called Dish to get the box authorized and I was up. The user interface is 99% the same and the remotes are identical.

While I was at it, I upgraded to the MPEG4 HD package that goes with our America's Top 100 package. So now Discovery, History, TBS, A&E, etc are all available in HD. Mostly a good thing except they have a bad habit of stretching SD video to fill the screen. Who are they trying to kid with that? Just do the black bars...

My first sat service was Voom, and this MPEG4 package includes all the old Voom channels with unfortunately a lot of the same programming. As with HDNET, they run the same stuff over and over - in Voom's case for years.

WCMH is rock solid and crystal clear. Clearly there is a bug in the 942 tuner code.

So far so good.


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## yottabit (Jan 2, 2008)

Thanks for the update... I will have to start complaining to Dish & WCMH to get someone to fix their problem. The 45-50 MPH winds we had up in Delaware a couple weeks ago blew my aerial to face due north instead of southeast... so right now I'm not picking up any OTA reliably, heheh. Maybe when the snow passes I'll get up on the roof and fix it!


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