Dallas ATSC 3.0?

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nickk
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Re: Dallas ATSC 3.0?

Post by nickk »

ATSC 1.0 uses a single modulation (8VSB). In order to get a lock you need to have ~16dB signal to noise.

ATSC 3.0 uses multiple modulation schemes on the same channel. The modulation used for the bootstrap information is usually a robust low bitrate modulation so a channel can detect as ATSC 3.0 with very poor signal-to-noise. This isn't useful for watching TV, it just means the channel can be detected as ATSC 3.0.

The ATSC 3.0 modulation schemes used to carry video can be anything from very robust low bitrate to very high bitrates where you need to be within 20 miles to receive.

So far we are seeing broadcasters mostly choosing ATSC 3.0 modulation schemes that have comparable range/coverage to ATSC 1.0. This is simply a choice made by the broadcaster.

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nickk
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Re: Dallas ATSC 3.0?

Post by nickk »

Signal power notes to keep in mind...

1) It is common for different stations to have different transmit powers or even different transmit shapes.

2) Different frequencies are affected differently, a little in propagation, a lot by the receive antenna.

3) The signal strength measurement is less accurate when there is no lock.

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Re: Dallas ATSC 3.0?

Post by xmguy »

signcarver wrote: Wed May 19, 2021 10:39 am AGAIN THAT IS ONLY FOR YOUR SITUATION there are countless areas that the opposite is true.

Here in phoenix the atsc 3.0 host stations are 35 and 61 (physical 27). For me 35 comes in at -58dBm and 27 comes in at -16dBm (because I am 5 miles from one of the towers broadcasting on physical 27). As a result comparing the hotness of the signal would be entirely moot if I try to compare 27 to what is broadcasting from a tower 20+ miles away. While 35 is pretty close to the station that hosts it's regular ATSC signal (33) which comes in (for me) at -42dbM (over 100%) compared to the -58dBm (84%) of the ATSC 3.0 signal which will be a more accurate comparison. For a more full disclosure 61 will come in at -38dBm strength on 15 from 20+ miles away. To make a statement that ATSC 3 will be hotter for a thread about Dallas when your situation is in Tennessee is completely irresponsible.


Lighthouse means they are "channel sharing"
your statement was:
xmguy wrote: Tue May 18, 2021 6:31 pm ATSC 3.0 is still in its testing period. Right now stations are doing it more as a show of; "look what we can do". That's why stations are lighthousing, and there are issues. Most markets aren't even online yet.


The reason for the lighthouse is that they must maintain their ATSC 1.0 signal for at least 5 additional years nothing to do with "testing" as such sharing is mandated to maintain service for the vast majority of television sets that are out there. I will admit that when I first viewed it, it came across on my phone was "ATSC 3.0 is still in its testing, PERIOD" (comma and emphasis mine but reading it that way struck a nerve) as though they are doing testing, it is beyond that for many.
I know what Lighthousing means, Yes. Because the FCC is forcing stations to use their existing DTV frequencies. So they have to get creative, and share their 1.0 signal off another station's carrier. Then that frees up their own RF channel for 3.0. This will all change once ATSC 3.0 is the mainstream, and likely only signal path. But that is atleast a decade off.

Also not everyone of us can afford the tech upgrade to get dB levels. I sure can't. So the only values I have are in percentages. Of what I can only assume it's converted from dB to % for the layman.

bweber
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Re: Dallas ATSC 3.0?

Post by bweber »

I have to ask, as a complete newb, Is anyone actually seeing a 4K picture in the DFW area? I'm in Arlington and I can't find anything better than 1080.
Thanks for tolerating my 'just getting started w/ATSC 3'.

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Re: Dallas ATSC 3.0?

Post by jasonl »

No one here or anywhere else in the country. The ATSC 3 broadcasts here are quite disappointing, being just 1080p30 and with picture quality that is worse than the legacy ATSC broadcasts, at least on sports and other high-motion shows. Since most of what I watch on Fox and all of what I watch on Univision and Unimás is sports, it's really a waste.

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Re: Dallas ATSC 3.0?

Post by xmguy »

jasonl wrote: Tue Jun 01, 2021 7:20 pm No one here or anywhere else in the country. The ATSC 3 broadcasts here are quite disappointing, being just 1080p30 and with picture quality that is worse than the legacy ATSC broadcasts, at least on sports and other high-motion shows. Since most of what I watch on Fox and all of what I watch on Univision and Unimás is sports, it's really a waste.
Are you talking about the jerking motions when there is fast movement? If so I see this even on the morning news on 3.0. Like if scenes pan, or arms/hands move quickly. However in my case it’s either 3.0 or nothing a lot of the time.

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Re: Dallas ATSC 3.0?

Post by jasonl »

Not really jerky, just not fluid. Watch sports on broadcast/cable/satellite TV vs. the same thing on an average web stream and you can readily identify the difference because the real TV will look smooth and the stream just isn't. Basically the same thing as comparing a soap opera vs. a regular TV comedy/drama. I don't know if your local stations are doing the same thing. Most stations presumably have their encoders configured correctly.

jaraco@jaraco.com
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Re: Dallas ATSC 3.0?

Post by jaraco@jaraco.com »

Channel 4 (ATSC 1 I think) seems to have dropped out again last week. Is intermittent outages the new normal for some stations? Is there anything a viewer can do other than re-scan for channels day after day hoping the signal comes back?

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Re: Dallas ATSC 3.0?

Post by kyl416 »

KDFW and KDFI are having problems with their mask filter and transmitter, so they were broadcasting at reduced power.

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Re: Dallas ATSC 3.0?

Post by jaraco@jaraco.com »

kyl416 wrote: Tue Jun 08, 2021 11:29 am KDFW and KDFI are having problems with their mask filter and transmitter, so they were broadcasting at reduced power.
We're continuing to be unable to reliably tune into KDFW for close to two weeks now. The signal is intermittent, mostly no signal or unviewable. However, the issue appears to be related to the HD HomeRun hardware. Taking the same antenna and connecting it directly to a Samsung TV instead of the HD HomeRun, the signal is clear and stable. We've power-cycled the HD HomeRun and re-scanned for channels and other things.

If HD HomeRun is unable to tune into a channel that a TV can, does that indicate a hardware issue? We're still using 20210501beta1 firmware - should we downgrade to the stable release? What other things can we do to troubleshoot?

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Re: Dallas ATSC 3.0?

Post by jasonl »

KDFI returned to full-power operation on 6/1. AFAIK, KDFW was never at low power. They are on the same tower but don't share a feedline or antenna so a filter issue with one would have absolutely no impact on the other.

Check your reception on KXTX 39.1. It's on the next adjacent channel to KDFW, and you probably aren't looking at it very much since it's Telemundo. If both are having problems, then I would start by adding an LTE filter (preferably the one SD sells) since T-Mobile's 5G signals live just above where channel 37 would be, and they can cause interference, especially on the higher channels, if you live near a cell tower.

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Re: Dallas ATSC 3.0?

Post by jaraco@jaraco.com »

KXTX seems to come in fine, so seemingly unrelated. It's KDFW channel 4.x (ATSC 1) that are failing to tune in where they did before a few weeks ago.

Any other ideas for troubleshooting?

jasonl
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Re: Dallas ATSC 3.0?

Post by jasonl »

Not really. I've had problems with KDFW for a long time, but it also affects my TV's tuners so I assume it's just something on their end. KDFW has been broadcasting on channel 35 since they first started broadcasting digitally, so they could still be using their original transmitter. Most everyone else has changed channels at least once if not twice, and those changes often required replacing an obsolete transmitter. In the old days of digital TV, broadcasters on UHF were still using tube-based amplifiers to boost the signal enough for transmission, because it was the only way to pump out enough power. Technology has now improved enough that everything new is solid-state, and the new transmitters put out a much cleaner signal than the old ones did. A cleaner source means they can stand up to noise better.

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