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ShaunMarie
Shattering Digital TV signals

We have a new HDTV with a built in digital tuner, and an older TV with a converter box. We have a newer directional rooftop antenna that we recently moved to the second story roof to try and help with our problem.

We get crystal clear reception on some analog stations, but are either totally unable to get the digital channels associated with that station, or we have frequent shattering of the signal, both audio and video. Weather, airplanes, and even semis on a nearby hill shatter the signals, even the signals from the closer and stronger stations.

We fear that once the analog stations go off the air, we will have few channels to watch, and poor and frustrating viewing of those.

Any ideas on what we can do? We called one of our favorite Public TV stations, they say it sounds like we've tried everything, and we will just not receive their signals after the switch.

canuk
Re: Shattering Digital TV signals

The digital television signal is generally carried the same as the analog signals..... in that sense they are the same.
Basically the audio/video componets are imposed in a radio frequency medium to deliver the information to your TV.

The over the air antennas need to be correct for the band of frequencies that are being broadcast. For example ... the analog stations may be in the VHF band ..... the digital broadcast may be in the UHF band .... which would require a combination VHF/UHF antenna to recieve both.

There are many other factors that could impede reception such as .... distance ... sight of line ... strength of signal ... etc..

Here's a couple of links for information check the first one for your specific area.....

http://www.antennaweb.org/aw/welcome.aspx

http://www.crutchfield.com/S-fUC9pDp9lM2/learn/learningcenter/home/antenna.html

JLMCDANIEL
Re: Shattering Digital TV signals

Usually an analog signal can be picked up on all sides of the antenna but for the digital signal you need the antenna pointed in the right direction as it is a narrower band so is much more directional. A lot of rotors are going to be sold after the change over. Not all stations broadcast digital yet. And yes you need the proper antenna to pick up the digital signal.
Jack

hedgeclippers
Re: Shattering Digital TV signals

I agree with you about the signal strength problem and I don't know how much we have spent ourselves on new television equipment and time to get things set up.
I agree with the above posters you certainly will need a rotor and in some areas you will need a signal booster that will need to be set up by an antenna professional as there are different strengths of boosters and the booster has to be put on the antenna itself and another part has to be plugged in inside the house.
I see by your post that you have already bought a new outside antenna and I am sure that you might have been told that you need a new hd antenna. From my research there is no such thing the antennas whether they say hd on them or not are the same as the old antennas and nothing has changed there.
However I have found out from a local antenna installer who wasn't trying to sell me a new antenna that size sometimes matters in buying an antenna for hd signals. So just getting a larger antenna or a signal booster might help you even though you have already bought a new antenna.
One thing I think has happened is that some stations are going dark with their hd signals as they are not yet required by law to put them on the air. I say that because when I first set up our equipment all of the stations were fine even the spanish ones that I don't watch and I haven't changed my rotor. So my best advice is go with a rotor and signal booster first and then see how that works. Things hopefully will work out eventually. Good luck to all of us.:)

goldhiller
Re: Shattering Digital TV signals

FWIW....I agree with hedgeclippers as regards the signal booster/amplifier. We don't have a rotor setup with a single antenna, but rather we have an antenna array. The vast majority of over-air signals available to us (that aren't simply reduntant signals/broadcasts) come from two directions and rather than spend time waiting for a rotor to realign ....I mounted two antennas on the same mast many years ago...one pointing NE and the other all most due north. The one pointing north is receiving stations 70+ miles away. It worked splendidly on analog and works even better with digital.

The "secret" to pulling these fringe stations is to have the right antenna (long boom/high gain) AND a mast-mount antenna amplifier. This is the two-piece amplifier that HC mentions. One component is mounted up on the mast and the other is inside the house (plugged in to 120VAC outlet). About $60 for these signal amplifiers....and they are the bestest of the lot of amplifiers for pulling in weak/fringe stations. If in doubt about how much "gain" you'll need...try to find one that has a variable gain control at the component inside the house. This will allow you to adjust the gain as needed. Too much gain can be as detrimental to picture quality as not enough gain.

On analog, we received 9 stations so well that folks thought we had cable or satellite reception. Not. With the converter boxes on the old sets, we pull in 16 crystal clear broadcasts with no adjustments to anything. Couldn't be happier.

The converter box you choose can make a big difference. I bought the Zenith DTT-901 boxes after doing some research. Best at pulling in signal/best and most pictures... in every review I read and only $20 + the coupon. (Took some hunting, but found them here at Radio Shack. Wally World carries an RCA model which rated second best in the reviews.)

If doing a multiple array antenna.......connect your upper antenna to your lower antenna with the old style 300 ohm twin-lead and then take both the combined signal from the lower antenna to the mast-mounted portion of the amp AND from there into the house with 75 ohm coax. (This will require one balum- 300 to 75 ohm converter - at the lower antenna) If you try to connect the two antennas together with 75 ohm coax and a coax splitter...the signal will back-feed between the antennas and you'll lose 25% or more of the signal strength on both antennas. Not a good thing at all.

(Make sure you use appropriate antenna stand-offs to support any twin-lead between antennas on the mast and DO NOT simply tape the twin-lead to the mast. Twin-lead is a true transmission line/antenna... in and of itself. Taping it in contact with the mast or allowing it to touch any type of uninsulated surface is a big no-no and will completely ruin your signal.)

ed21
Re: Shattering Digital TV signals

Something odd I've noticed is that the best antenna direction for the analog station is not always the best direction for the digital broadcast. So you may have to adjust the antenna a bit. I have a channel master rotor with a digital readout that makes repeating an antenna position easy.

goldhiller
Re: Shattering Digital TV signals

Another reason I prefer a multiple array to a single antenna with rotor is......if you have multiple sets around the house and people want to watch progrmas from stations that are in physically different directions....there is no fighting over which way the antenna will be pointed.

A multiple array is a good thing, IMO. The cost of an extra antenna is no more than the cost of the rotor. Probably much less. No motor or control unit to wear out/burn out either.

carlb
Re: Shattering Digital TV signals
ed21 wrote:

Something odd I've noticed is that the best antenna direction for the analog station is not always the best direction for the digital broadcast.

This may be because, for good analogue reception, you want the strongest signal - for digital reception, you want the best signal, which means the one with the fewest reflections and the least fading, among other things. Often these are the same, but occasionally there will be some obstruction in the direct path between your antenna and the station which can cause unexpected results. Moving the antenna to another location - whether higher or merely clear of an obstruction - can in some cases make a huge difference. I've seen cases where "aim at the strongest reflection" with a directional antenna can help; I've also found any attempt to use antennas indoors to be unpredictable. In some cases, moving an indoor antenna a few feet makes the difference between great signal and no stations at all - the building had aluminium siding and finding the location where the antenna could 'see' the desired signal through a window while the siding blocked interfering signals from other directions would suddenly, inexplicably cause a marginal signal to improve.

UHF is fickle and DTV is all or nothing. Take this stuff out into the "real world" and the signal does pretty much as it darned well pleases...

carlb
Re: Shattering Digital TV signals
ShaunMarie wrote:

We get crystal clear reception on some analog stations, but are either totally unable to get the digital channels associated with that station, or we have frequent shattering of the signal, both audio and video. Weather, airplanes, and even semis on a nearby hill shatter the signals, even the signals from the closer and stronger stations.

This sounds a lot like an obstruction in the signal path - perhaps a building or other large structure between you and the station. The higher the channel frequency (and most HDTV is UHF at the moment) the worse the obstacle course appears. Odds are that trucks and airplanes, in this context, are merely reflectors. The signal they reflect may add to the main signal - or it may distort or weaken it. While a more directional antenna will let you ignore many otherwise-troublesome reflected signals, if the TV is having problems seeing the main signal but is still sensitive enough to the reflected signals that channels will freeze intermittently? You might want to move your antenna in an attempt to see around the obstruction. A lot of time-consuming trial and error is involved, but odds are that you will see a difference.

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