#166447 - 02/04/09 10:15 PM
Re: Digital TV (Again)
[Re: Am_Fear_Liath_Mor]
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Pooh-Bah
Registered: 09/01/07
Posts: 2432
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I get all my TV, what little I watch regularly, over the air, OTA, with a moderately large antenna perched on top of 30' of conduit. An antenna rotator and line amplifier complete the rig. The whole thing cost about what my neighbors pay for cable in around three months. With digital TV the rotator is pretty important. A few degrees can make a real difference as digital TV is essentially go/no-go. You either get enough signal to assemble a nearly perfect picture or you get nothing at all. With analog the picture would degrade until you had snow with just a hint of a picture you could just about make out if you squinted just right and used your imagination. With digital it is pretty much all or nothing. So far I get more channels but lost NBC. No big loss, the only show I liked was "Dexter", and a few sources seem to say that come Feb 17 NBC will have digital service in this area. I found these sites helpful when determining where to point my antenna: http://www.antennaweb.org/aw/Address.aspxhttp://www.tvfool.com/
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#166451 - 02/04/09 10:33 PM
Re: Digital TV (Again)
[Re: Art_in_FL]
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Carpal Tunnel
Registered: 08/03/07
Posts: 3078
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With digital TV the rotator is pretty important. A few degrees can make a real difference as digital TV is essentially go/no-go. You either get enough signal to assemble a nearly perfect picture or you get nothing at all. It may well be beneficial to put back the transition date from February to June, as I'm pretty sure its bound to save a few lives. (as hundreds of people throughout the land fall off slippery wet icy roof tops trying to install or fix their antenna on the big day in a few weeks time )
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#166476 - 02/05/09 11:52 AM
Re: Digital TV (Again)
[Re: Am_Fear_Liath_Mor]
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Member
Registered: 05/22/07
Posts: 121
Loc: KY
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#166488 - 02/05/09 02:37 PM
Re: Digital TV (Again)
[Re: Mike_in_NKY]
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Rapscallion
Carpal Tunnel
Registered: 02/06/04
Posts: 4020
Loc: Anchorage AK
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I'm inlcined to agree with Martin in general. With traditional analog, I could get a 12 db sinad with as little as .3 microvolts on most mainline systems. When we went to digital conversion, I figure I lost as much as 5 db of usable signal as the digital systems would struggle to decode much below .5 or even .6 microvolts. Even at that level, the cut out was usually more than most users would tolerate. With analog, you'd get static at 12 db sinad, but you always had the signal, unless you set your squelch too tight.
Even with FleetSatCom in the Navy, signal degradation and propogation loss was a common bugaboo. It was more than frustrating when we'd be sitting at our good old R-390s chasing russian code and the damned df equipment wouldn't discriminate the signal out of the grass. I could hear the signal just good enough to make copy, but the stupid million dollar hardware couldn't even tell it was there. But that's besides the point, the sat come guys were constantly fussing with their gear trying to maintain a signal lock on a TDM from the Pac Sat and half their traffic would be lost as the ship rolled which usually caused a 30 db signal swing as they lost peak azimuth. You'd never have an issue like that working analog.
I do agree, distinguishing between signal quality and the quality of the programming is important. In my opinion, it doesn't matter what signal format they use these days, the programming stinks, and I'm not even sure free is worth it anymore.
As for audio signal level during commercials, if it is just compression, why is my db meter reading twice the signal level during commercials? Sound power is sound power, and it doesn't matter if you are feeding audio fidelity at 10 Khz if the majority of the audio is voice because the power band for voice is less than 5 Khz, so the only way the voice audio level goes up is if someone is jamming the gain over 0db. However you want to put it on the front end, the result is a matter of fact that audio for commercials on some channels is twice the power level at the tv output as what it is during the program. I would bet good money if I put an O'scope on the audio signal in my tv set that I'd see the peak voltage significantly higher during the commercial than during the show. Also having worked on commercial broadcast equipment, I've seen plenty of examples where the rf signal has been overmodded and in fact has bled into adjacent channel space. How does that happen if the audio input isn't being overdriven?
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools. -- Herbert Spencer, English Philosopher (1820-1903)
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#166489 - 02/05/09 02:37 PM
Re: Digital TV (Again)
[Re: Am_Fear_Liath_Mor]
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Pooh-Bah
Registered: 01/21/03
Posts: 2203
Loc: Bucks County PA
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If the DTV terrestrial broadcast signal is very weak, don't you have a free satellite broadcast such as the equivalent of the European DVB-S service which broadcasts the same channels you would have picked up using your UHF antenna.
I guess that's the price we pay for not having to have a television license system, huh? There's no "free" sat tv here in the USA that you can get with less than a swimming-pool size dish, and even at that, it's mostly encrypted mush. Until I was in other countries, I always thought that the proliferation of sat dish systems was evidence of paying subscribers to TV services similar to our DishNetworks here in North America. I was astonished to find out that it was just a system that's basically a really, really, really tall antenna tower for free broadcasts. What's more amazing is that in places with the DVT-B standard, I can get a $19 plug-in device for a cheap laptop and get a good signal almost everywhere. I just can't believe how much we've let our broadcast infrastructure become a relic - and how much this DTV thing here in the USA is a boondoggle.
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#166490 - 02/05/09 02:39 PM
Re: Digital TV (Again)
[Re: Art_in_FL]
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Pooh-Bah
Registered: 01/21/03
Posts: 2203
Loc: Bucks County PA
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With digital TV the rotator is pretty important. A few degrees can make a real difference as digital TV is essentially go/no-go. You either get enough signal to assemble a nearly perfect picture or you get nothing at all.
I am unaware of any system that automates the positioning of the antenna based on the currently tuned signal. Are you?
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#166491 - 02/05/09 02:47 PM
Re: Digital TV (Again)
[Re: benjammin]
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Pooh-Bah
Registered: 01/21/03
Posts: 2203
Loc: Bucks County PA
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As for audio signal level during commercials, if it is just compression, why is my db meter reading twice the signal level during commercials? Sound power is sound power, and it doesn't matter if you are feeding audio fidelity at 10 Khz if the majority of the audio is voice because the power band for voice is less than 5 Khz, so the only way the voice audio level goes up is if someone is jamming the gain over 0db. However you want to put it on the front end, the result is a matter of fact that audio for commercials on some channels is twice the power level at the tv output as what it is during the program. I would bet good money if I put an O'scope on the audio signal in my tv set that I'd see the peak voltage significantly higher during the commercial than during the show. Also having worked on commercial broadcast equipment, I've seen plenty of examples where the rf signal has been overmodded and in fact has bled into adjacent channel space. How does that happen if the audio input isn't being overdriven?
Well you and I both know that overmodding a commercial Xmit site is against FCC rules, esp when you start slamming adjacent channels. But the audio portion of the programming, was, at least in 1993, which was the last time I made a commercial for broadcast, clearly and specifically limited to 0db average, and we had stuff rejected for broadcast for over-modulation. Now that said, even way back then - and more so now - there are astonishing tricks they can do with sound, especially with various modulation envelopes that mess with the phasing and frequency of the signal in a way that both pushes voice way forward - and as you may have heard in some of those care commercials where they mumble the terms and conditions disclaiming the previous 28 seconds of offers, "smearing" the voice into music via a digital process that "averages" sounds together similar to the way a digital imaging tool can average images.
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#166501 - 02/05/09 03:31 PM
Re: Digital TV (Again)
[Re: benjammin]
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Member
Registered: 05/22/07
Posts: 121
Loc: KY
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I do agree, distinguishing between signal quality and the quality of the programming is important. In my opinion, it doesn't matter what signal format they use these days, the programming stinks, and I'm not even sure free is worth it anymore.
+100 on that!
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#166517 - 02/05/09 07:01 PM
Re: Digital TV (Again)
[Re: Mike_in_NKY]
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Rapscallion
Carpal Tunnel
Registered: 02/06/04
Posts: 4020
Loc: Anchorage AK
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Yes, there are a host of techniques for filling the voids in the mod envelope. The bottom line is that the output at the tv end is going to result in a significant average audio power level increase. From some of the readings I've taken, that audio output is pushing 6 db over the program level. It is annoying.
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools. -- Herbert Spencer, English Philosopher (1820-1903)
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#166555 - 02/06/09 02:22 AM
Re: Digital TV (Again)
[Re: benjammin]
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Geezer
Registered: 01/21/04
Posts: 5163
Loc: W. WA
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"Were I being affected right now economically, the dish would be the first thing in the junk pile for sure. "
When I lost my fairly decent job, sat TV was the first thing to go. It just wasn't worth it.
The next thing I canceled was my garbage.
Wait, I'm repeating myself...
Sue
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