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post #5161 of 5175 Old Yesterday, 07:24 AM
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Originally Posted by nsa1062 View Post
Everywhere I've lived, analog CH 3 was always plagued by ghosts and interference when using any type of indoor antenna. CH8 and the UHF's generally looked fine.

The only remotely close FM is 107.3 in Grafton Twp. about 5 miles away. All the others are over 20 miles. It certainly wasn't a ham (as that would be sporadic).
Ditto, on Analog 3, (& being subjected to co-channel), 8 & 19 were the powerhouses, quite opposite now.

Same with WICU, all I needed was the rotor for that, now unrecievable period.... now Erie's weakest.

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I gotta know. What is ATSC3?
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Means you need a newer TV or converter box.
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post #5162 of 5175 Old Yesterday, 07:53 AM
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Originally Posted by Bismarck440 View Post
Ditto, on Analog 3, (& being subjected to co-channel), 8 & 19 were the powerhouses, quite opposite now.

Same with WICU, all I needed was the rotor for that, now unrecievable period.... now Erie's weakest.



Means you need a newer TV or converter box.
Yes, but from what I've heard. The new technology required would be very easy to make and sell for dirt cheap, like a few bucks. And if your TV has an HDMI input, it may just be as easy as plugging in a small piece the size of a flash drive. TVs manufactured for Europe are already equipped with this technology. We're just lagging behind here.

By the way, co-channel interference on channel 3? From what, E-skip?

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Originally Posted by Trip in VA View Post
Yet on the HDHomeRun I have sitting there, the UHF signals are at 100%, and the low-VHF signal with the dedicated roof antenna at the top of the mast barely breaks 70% on a good day.
Those signal indicators on the tuners are deceiving. Don't those just measure the signal to noise ratio? A true noise margin reading in dB would be a lot more revealing and give a more fair comparison. But also, aren't digital low-VHF power levels set really low because it doesn't take much to get the signal to travel far? So you could have a 70% signal at 10 miles out and also have a 70% signal (S/N ratio) at 50 or even 100 miles on a low-VHF channel. I heard the FCC proposed increasing maximum powers on low-VHF. Wouldn't that make a more robust signal? Technically, it's mainly the tower height that dictates how far a signal will reach. Power just makes a signal more robust, and it would fill the coverage area with a more useable, more powerful signal. And I also heard that adding circular polarization would boost a signal by twice as much.
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post #5163 of 5175 Old Yesterday, 08:04 AM
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Originally Posted by Andrew K View Post
By the way, co-channel interference on channel 3? From what, E-skip? .
Just electrical/impulse noise interference mostly (though E-skip was occasionally a problem in the summer). One of the first PC's I owned, couldn't turn it on if anyone was watching channel 3 in the house, as there would be diagonal lines covering the picture. And of course anyone running a vacuum cleaner/electric drill/blender (any motor with brushes) would obliterate CH3
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post #5164 of 5175 Old Yesterday, 08:12 AM
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Same here, 8 came in the best. 19 was the best UHF; 23, 25, and 61 also very good. 5 was so-so (usually watched ABC on 23 when I lived in Hinckley, as it came in much better). Only difference in Litchfield is the Akron stations (23 especially) are marginal (23 was full of ghosts and smearing in analog). Cleveland is about the same both places.

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Originally Posted by Bismarck440 View Post
Ditto, on Analog 3, (& being subjected to co-channel), 8 & 19 were the powerhouses, quite opposite now.

Same with WICU, all I needed was the rotor for that, now unrecievable period.... now Erie's weakest.



Means you need a newer TV or converter box.
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post #5165 of 5175 Old Yesterday, 08:46 AM
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Originally Posted by nsa1062 View Post
Just electrical/impulse noise interference mostly3
Bingo!! That's exactly the problem with low-VHF, but that's not to say that there aren't ways to fix it. Your signal indicator on the digital tuner merely gives you the signal to noise ratio, and if you got any electrical interference nearby from a device like a computer, that will definitely give you a perceived lower signal reading. It doesn't necessarily mean that the actual signal is unusable. It just means that you need to find ways to fix the problem. That's why I think that power increases, circular polarization, and merely getting the antenna away from the interference will bring the signal in. WKBN/41 pegs the signal meter up to 100% even though I know that being 50 miles away, it can't be that high. It's just that the signal is clean and free of interference. The actual noise margin for WKBN/41 is 3.9 dB. On the other hand, WEAO/50 is 75.3 dB where I live, and both show the same 100% reading.

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post #5166 of 5175 Old Yesterday, 09:32 AM
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By the way, if you have a low-VHF digital channel, most of the problem is that you can have a workable noise margin in the air to begin with, but after all your losses, the noise margin would drop to well below the decodeable threshold. And that's the problem that most are experiencing.

For UHF, the noise margin correction factor is zero, but for low-VHF, it is typically around a 15 dB loss when you factor in common interference (the interference that everyone gripes about with low-VHF). So it's really not that drastic (unless you're running the vacuum or blender). And using an indoor antenna as opposed to an outdoor can subtract around an additional 20 dB from your noise margin. Also, the fact that it's low-VHF and requires a large antenna which usually isn't feasible can mean that the antenna won't give you an additional needed dB.

So in other words, get the antenna outside and away from interference and that alone can give you an additional 35 dB. That equates to a gain factor of 3,000 times!! Getting a bigger antenna is just icing on the cake.

You can have an excellent noise margin of 50 dB on a low-VHF channel and still receive nothing if you have an indoor antenna. The resulting noise margin would end up being below zero...

Example
NM (air) 50
NM (correction factor) 25 (interference from common electronics on low-VHF)
Penetration Loss (dB) 22 (indoor antenna must penetrate building material)
Antenna Gain (dBd) 2 (basic indoor antenna)
Preamp Gain (dB) 0 (no preamp)
Preamp NF (dB) 0
Distribution Losses (dB) 1 (short coax run)
Tuner NF (dB) 6 (typical value)

Net NF (dB) -2 (No watchable picture)
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post #5167 of 5175 Old Yesterday, 09:39 AM
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Originally Posted by Andrew K View Post
So in other words, get the antenna outside and away from interference and that alone can give you an additional 35 dB. That equates to a gain factor of 3,000 times!! Getting a bigger antenna is just icing on the cake.

You can have an excellent noise margin of 50 dB on a low-VHF channel and still receive nothing if you have an indoor antenna. The resulting noise margin would end up being below zero...
Not everyone can put up a huge, old-school, low-VHF antenna outside. And it still doesn't solve the thunderstorm/E-Skip issues.
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post #5168 of 5175 Old Yesterday, 09:50 AM
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Originally Posted by nsa1062 View Post
Not everyone can put up a huge, old-school, low-VHF antenna outside. And it still doesn't solve the thunderstorm/E-Skip issues.
A huge old-school antenna will certainly help, but it's not as crucial as you think. Most low-VHF antennas only provide a few decibels of gain... like the AntennaCraft Y5-2-6, which provides +4.9 dB. You could go much smaller with rabbit ears which provide -2 dB, and yet you're only sacrificing 6.9 dB. It's the fact that getting the antenna outside and away from interference that is the real issue. Regarding thunderstorms and e-skip, there's nothing you can do to control mother nature, you just live with it .
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post #5169 of 5175 Old Yesterday, 09:54 AM
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Originally Posted by Andrew K View Post
Yes, but from what I've heard. The new technology required would be very easy to make and sell for dirt cheap, like a few bucks. And if your TV has an HDMI input, it may just be as easy as plugging in a small piece the size of a flash drive. TVs manufactured for Europe are already equipped with this technology. We're just lagging behind here.

By the way, co-channel interference on channel 3? From what, E-skip?
Scary thought, so this would be a HDMI based tuner (seperate remote?

Likely skip coming from the South, in the rare occasions when 3 used to sign off, WSAZ from Huntington sometimes appeared.
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post #5170 of 5175 Old Yesterday, 10:06 AM
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Quote:
Originally Posted by Andrew K View Post
Those signal indicators on the tuners are deceiving. Don't those just measure the signal to noise ratio? A true noise margin reading in dB would be a lot more revealing and give a more fair comparison. But also, aren't digital low-VHF power levels set really low because it doesn't take much to get the signal to travel far? So you could have a 70% signal at 10 miles out and also have a 70% signal (S/N ratio) at 50 or even 100 miles on a low-VHF channel.
I've tested the HDHR against my Sencore analyzer and the readings are basically 1-to-1. I know what the raw power and MER (SNR) of a signal is based on what the HDHR tells me. In fact, because of that, I made sure my auto-scanner page has a (hidden) mode to do that translation:

http://m.rabbitears.info/index.php?r...tno=1&unit=dBm
http://m.rabbitears.info/index.php?r...no=1&unit=dBmV

(Ignore the number for WSET, we actually don't have a high-VHF antenna on the roof, so it's lower than it otherwise would be.)

The problem is that received power largely doesn't matter in this case. Yes, WBRA is on-par with the UHF signals. However, if the MER is in the dirt, it doesn't matter how strong it is. The minimum signal required for a DTV signal to decode with no interference is -84 dBm. So looking at my link above, you can look at channels 2, 5, and 6 and see the noise floor is, on average, -85 dBm! (Channel 4 has a ham radio beacon on it, so it's not showing you the noise floor.) That means the signal needs to be at least 20 dB stronger than the minimum, at my parents' very rural house, for a decode of any kind. If you want any kind of buffer, for random variation due to atmospheric conditions, it should really be about 8 dB higher than that, and overcoming electrical interference from lightning and appliances is at least another 10 dB above that (not sure of the exact number). They are 12 dB above the bare minimum for a decode as of right now, and there's no larger low-VHF antenna made. So they can watch WBRA much of the time, but not during e-skip, thunderstorm season, or when the vacuum/blender/other device is running anywhere in the house, and they experience drop-outs whenever light switches are turned on or off or the microwave door is opened or closed. Again, all with the antenna "outside and away from interference".

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I heard the FCC proposed increasing maximum powers on low-VHF. Wouldn't that make a more robust signal?
You heard wrong. If they did, then yes, but only if all stations would implement it. You can lead a horse to water. But of course, there is no power increase on the horizon for low-VHF, so it's academic anyway.

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Technically, it's mainly the tower height that dictates how far a signal will reach. Power just makes a signal more robust, and it would fill the coverage area with a more useable, more powerful signal.
Technically true, yes, assuming you're not trying to blast a signal over an increased noise floor.

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And I also heard that adding circular polarization would boost a signal by twice as much.
It doubles the power bill, and it does double the signal (which is all of a 3 dB boost, max) but that boost is mainly seen on indoor antennas. If your roof antenna is horizontally polarized, as most are, then it will see little or no benefit from the circular polarization unless you're watching via a multipath reflection.

- Trip

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post #5171 of 5175 Old Yesterday, 10:07 AM
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Originally Posted by snowdog 88 View Post
Not sure what the case is, but it seems like it takes forever for stations to change the label. (I think WKYC forgot after becoming the Justice Network). Some TVs, however, need to be rescan in order to update the label.
My Westinghouse can still manually be changed, in fact I think it has to unce programmed in, if I rescan I wipe the occasional Out of town stations away to unusable. I like them programmed in but hide them.

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I just noticed something odd - during the commercial break between movies they showed a promo for Movies! and stated that it was coming in April - isn't what we're seeing the actual network? Just curious, cuz I thought Movies! was already airing.
I saw that & can see where that is misleading.
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post #5172 of 5175 Old Yesterday, 10:07 AM
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Originally Posted by Andrew K View Post
Regarding thunderstorms and e-skip, there's nothing you can do to control mother nature, you just live with it .
Which is why stations avoided low-VHF like the plague, because telling your viewers that is akin to telling them to watch someone else.

- Trip
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post #5173 of 5175 Old Yesterday, 10:43 AM
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Originally Posted by Trip in VA View Post
Which is why stations avoided low-VHF like the plague, because telling your viewers that is akin to telling them to watch someone else.

- Trip
Thanks for your input. I only know from my past experience with low-VHF digital reception, and mine wasn't as bad as what most people describe. Although I do remember thunderstorms being an issue for me.

So from the sound of it, low-VHF is now pretty much just a wasteland, and it's not being put to good use. There has to be a good use for it though. I wonder if ATSC 3.0 has the same problems with low-VHF compared with 1.0.
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post #5174 of 5175 Unread Yesterday, 07:32 PM
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I was another one struggling with WKYC on RF 2. I nearly kissed the ground when they lit up RF 17.

Bottom line, the perfect conditions needed for clear, interference free reception on low VHF just don't exist in 2015.
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post #5175 of 5175 Unread Today, 07:19 AM
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I didn't have too many problems with WKYC RF 2. The only interference I can recall was a partially decoded signal while using the egg beater and brief pixelization every time the alarm on the dryer went off.

Newer is not always better.

HDTVs: RCA L37WD12, Vizio E371VL, Samsung UN46H5203
DTV Converter Boxes: Zenith DTT900 & DTT901, Magnavox TB100MW9
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