I think the whole object is to dispose of over-the-air transmission. For 37 years I've had some mountain or other in the way, so for the last 25 years or so I've had cable... I'd never go back.
...Jim Thompson
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| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
Well, after looking at the standards I had a hunch that this would happen. They probably never did real field tests, at least I haven't read about many.
It just irks me that a company can foist $40/mo plus on us just for the "privilege" of watching the news and some old movies because they were handed a quasi-monopoly. It's not about being able to afford that, it's about the principle. Every year they dip into the pot deeper, claiming "programming costs have gone up" and yada, yada, yada.
Also, I am afraid other people in this area will react more belligerant once they realize they've been had over the barrel. Possibly after investing some four-digit sum into a "new and improved TV experience" that then fails to materialize. Soon the blame game will start and shortly thereafter it will be mined for political gains. And that won't be pretty at all.
Which one of these? I believe you mentioned it was a Channel Master:
If it's one of the 36xx series, they're similar to the Radio Shock monstrocity that I modeled. (I'm still looking for where I buried the NEC2 files).
Ladder? I thought you had a tower or pole. If you're that close to the ground or roof line, you're going to get a quite a few local reflections.
It wasn't really all that bad. What I should have done was contact the local CATV company and ask them if they had any unused single channel antennas at the local headend. I know they have these because they're moving away from over the air feeds, and switching to fiber and satellite distribution. However, I built my own. The first prototype was a piece of PVC pipe, with welding rod for elements. Dual T-match and balun on the driven element. Once I got one channel working, and determined that the others would probably work just as well, I built 3 more antennas and amps. Figure on one weekend per antenna.
Nope. The future is "personal TV", where you wear a 3D headset and are literally immersed in the story. Anything less than terrestrial fiber doesn't have the bandwidth. You read it here first.
Notice how the deadline on Feb 17, 2009 is AFTER the election in Nov
2008. Congress and the FCC know a problem, especially when they create it. If there's every going to be a "popular uprising", it will be over something like the loss of analog TV.
Then, they are NOT coming from bouncing around the indicent path. They're coming from the sides, or more likely, from the back. Since your antenna is apparently within easy reach (on a ladder), you get to try a really dumb experiment. Find a 20ft fiber glass window washer or painting telescoping pole. Mount the biggest wire mesh you can find to the top to block the signal. Move it around the sides and back of the antenna until the reflections (ghosts) disapper. If you have multiple reflections, this has the potential of making things worse, but at least you'll get a clue as to from which direction the reflections are coming from. My guess(tm) is from the back. If the wire mesh makes it worse, try again with something that absorbs RF (wet towel works nicely) and doesn't reflect RF.
If you don't want to have the neighborhood suspect your sanity by running around your roof with a giant fly swatter, find a bow tie antenna (with a flat reflector) and try it on one of the UHF channels. This won't solve the VHF problem, but for UHF, it has a highly desireable high f/b ratio. If the reflection is from the back, as I suspect, then it should eliminate it.
Also, please try not to fall off the roof. You have but one life to sacrifice to the HDTV gods.
There's also an antenna selector web site at:
It just declared that there are no TV stations that I can see at my location. Oh well.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
None of those, AFAIK it's a commercial grade version for CATV heads. Very old and not a spot of wear (other than the occasional bird droppings), pretty impressive.
The mast is bolted to the side of the house and you have to get on a ladder to untighten it, turn the whole mast, then retighten.
So all pedestrians are now schlepping fibers behind them?
And that one could be huge. There is stuff that voters forget, and then there is stuff they don't forget. And you can be sure that this will be mined in the election after that one, along the lines of "these are the guys who dunnit".
I've tried those tricks. Thing is, reflections (bounces) seem to happen multiple times. Meaning a back reflection comes bouncing back from the front again. That's why it gets really bad when a 747 freighter glides in, probably because it's a nearly perfect reflector.
Quote "These large, multi-element rooftop antennas are used in weak signal areas for maximum possible TV reception. These antennas can be used in ANY LOCATION, but require an amplifier and roof mounting to receive blue and purple channels. Amplifiers are not recommended for yellow channels."
The stuff I remember (vaguely) was greatly refreshed by reading and the related pages on the "Grand Alliance" and "FCC adopts...". They started with this in the late 1980's, came up with several systems around 1991 and combined the results into the standard by 1995.
I'm pretty sure that nobody had put up anything but a test transmitter by then. I think some groups thought that they could lobby their way around it as COFDM got better developed after 1995.
You also have to remember that in the decentralized US broadcast industry, signal quality is a competitive tool. (Or used to be, now that most everybody uses cable or satellite).
Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)
I played with the Vizio for a while. I couldn't get the picture "right", so decided to go a bit up-scale for my own. I was considering Olivia (?) and Westinghouse too, but decided I'd rather spend a little more money now than be disappointed for years. An HDTV is too obvious to get wrong. ;-)
It's all built with the good stuff. None of this plastic stuff. No shortcuts. Antenna -> mast amplifier -> quad shield -> big distribution amp in the comms closet -> some more quad shield -> TV. All runs are dual quad shield so content can be fed back to the head amp. After installation I did some tests such as feeding a gen signal all the way back to the mast head and then checking it coming all the way back. Was perfect.
It's fine. The only minor difference is that its black level isn't quite as black as that of >$1500 units. But that difference wasn't worth $750 to me. It's way too bright anyhow so I'll probably reduce the backlight juice a bit (has a menu setting for that). Reviews were favorable as well except that many rated its audio as being a bit measly. Strange thing, I think the audio is great.
However, since DTV is of inferior reliability it might be that only the VGA function will be useful here starting in 2009.
Despite everything being perfect, you should try disconnecting everything from the antenna and running a simple 100' cable to the TV. If you can drag the TV out to the antenna, that's even better.
Believe it or not but that's what I did to initially find the best position for the antenna. TV out on the deck, about 40ft of quad shield, me on the ladder with binoculars in the belt. There was no difference in image quality after bringing it back inside where it was fed via the distribution network.
No, the problem is the mandate. Fact is, analog works better.
Nope. Just bought a brand new one. Supposedly has a pretty good tuner. Besides, I've heard from others who plunked down north of $2k that it ain't much different for them either.
That I might have to do, sacrifice some channels so that others can be received better. This will mean a net reduction in TV content but fine with me.
Seriously, you can't possibly get a better one except by building your own. Which, of course, is an option but TV ain't that important.
Fact is: Analog TV and a $300 set worked just fine. Then came a mandate from above that we all "will like and thus have to eat" DTV. Now digital TV and a $750 set does not work reliably. That rationale is pretty simple to me and others out here.
That's what many out here will probably start doing. Except the folks on sat downlinks, they'll be out of the game and they'll probably concentrate more on DVD renting. Anyhow, if this is the trend and I were a TV station employee I'd be a bit concerned about job security. Usually goes like this: Less viewers -> less ad revenue -> pink slips.
I am willing to make changes as long as they are reasonable. Signing up for some $40-50/month cable deal isn't IMHO.
Ah, but the congress critters are not stupid. They're using our tax dollars to give away rebate coupons for DTA (digital to analog) TV converter boxes:
Again, note that the date was safely set to AFTER the Nov 2008 election, where the likely culprits would be safely out of office.
Grinding.... 10*10^-6 seconds * 3*10^8 meters/sec = 3km path difference. I'll guess that the stations are about 10 miles or
16km distant. Grinding the trig, that puts the 747 flying at 5km altitude at 8km range (midpoint). That's a bit high for a 747 on approach.
A more reasonable 747 approach altitude might be perhaps 300 meters, which would yield a single bounce reflected path length difference of
If there are multiple bounces along the path, it will be roughly multiples of this path delay. 10 microseconds would be about 12 to 15 bounces, which methinks is improbable. Have you looked at the composite video signal coming out of the TV? With a decent trigger, it should show the ghosts.
Back to the original question, there are apparently various patents for methods of TV ghost elimination for both analog and digital TV. I don't have any experience with these so I can't seperate reality from science fiction. Looks like an adaptive equalizer will work work HDTV. From what I've skimmed, most equalizers are more complexicated than what I could throw together in an afternoon. This one looks interesting:
See other patents in list of citations or searching for "television ghost"
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
It's a bit different. Echoes coming off slopes far behind us, hitting the 747 at 800ft or so 1-3 miles out front and then that bounces back into the antenna together with the direct signal.
I've looked at the cerration pulses because they are nice and crisp under normal reception condition. And oh boy do they squirm when that
747 glides in. Sometimes I thought I could actually guess the approach speed sitting there at the scope.
Heck, we did this stuff back at the university and that was a long time before those kinds of patents. So if I'd dig a lot I'd probably find prior art. However, the TV industry remained blissfully not interested. That was in Europe and then the TV manufacturers keeled over one after the other. Why was I not surprised about that?
On a sunny day (Mon, 26 Nov 2007 21:01:15 GMT) it happened snipped-for-privacy@eskimo.com (Mark Zenier) wrote in :
Yes, I have just read the links you mentioned. Sure, in 1999 50% had access to ATSC transmissions. Also this 50% experienced severe multipath problems. The broadcasters, being 'competitive' did not really want to lose viewers, and voices were hears (Sinclair for example) to change to COFDM. Of course the 'standard' was set, and it was a bit late to change. As many had invested time and money in ATSC.
Cases like Joerg's show that sort of ignoring the problem is no solution, what can he do?
It somehow reminds me of NTSC (we say Never Twice Same Color), it was a new system, but it had flaws, it was not a bad system, but sold with the flaws, Maybe US should have been a bit more humble and review things in 1998, as then COFDM results were also known.
I mean, ask yourself, IF US had known about PAL's line alternating phase, WOULD it have adapted such a thing and not NTSC?
There are pride and ego and politics and money at work. 'We can always improve it later (can we?) and sell a new set' guarantees continuous income for the industry.
Probably, but that's the whole point in that case - hindsight is always 20/20. The developers of the NTSC system were starting from scratch, whereas PAL was developed in an environment where the real-world performance of the NTSC method was already known, through a number of years of actual experience. But it was certainly too late for those countries which had already adopted NTSC to try to force a change on their populace (and, as it turned out, little need to do so, since the problems with NTSC diminished to insignificance with continued improvements in receiver design).
SECAM, of course, is another thing altogether....;-)
On a sunny day (Tue, 27 Nov 2007 12:00:22 -0700) it happened "Bob Myers" wrote in :
SECAM = Systeme Encenee Contre l'Amerique (excuse my French). That means so much as 'System Created Against America'. Now that was the time of Charles de Gaulle as French president. Not a bad president, he gave France the bomb too. SECAM was done together with the Russians, it was great for recording, but you could not fade in or out... the color subcarrier was FM modulated. So they used PAL in the studios.
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