UHF Reception -pixellation and bad signal

[Jnktwnman]

Early this year I had an outside antenna (Antenna craft 5884) installed on the roof of my 2.5 story house. Reception for VHF has been outstanding.

Unfortunately, however, my UHF channels 17 & 29 lose their signal for seconds at a time and pixellate frequently enough to be annoying enough to want to turn the TV off.

My installer has said that I should try an amplifier at the set - I have tried a Radio Shack amplifier that has had either no effect (when turned down) or negative effect when turned up.

The TV Fool report (attached) says the transmitters are nearby.
Is there anything that I can do to get these stations to be consistent ?

TV Fool Report:

Thanks for any help

What does signal strength show when the picture is good and bad? . How many Tv's connected? . What is the connection set up now? . The signal strengths are very strong at 61 and 71 NM(dB) . . 0 NM (dB) is the reference point for trouble free reception. . Check the coaxial cable connectors , look inside the connector and see if the foil shied or shield wires are pushed in toward the center wire conductor , if so push the shield and wires away from the center conductor. . Also a good idea to clean the foam that is in between the outer foil shield/shield wires and center wire conductor. I do it with a small flat blade screw driver and blow it out . Also make a DIRECT coax connection to One Tv or converter box and Unplug All Other Electronic And Electric Devices so as to eliminate sources of interference. . Many people stack and jam electronic and electric devices including computers. . This is not the thing to do with Digital Tv. . One person wrote in that when the computer was on , some Tv channels were lost and when the computer was off the Tv channels were Ok. Also go to http://www.dtv.gov , and read and watch the video about Double Rescanning . . Please contact us back we all like to know how it's going. O and also it might help to turn the antenna a little , the reason is multipath/signal reflections off of buildings , hills/mountains or even trees , turning the antenna a little will move the receiving elements of the antenna so the reflected signal is not so strong.

[Dave Loudin]

You could probably get by with a paper clip and get everything you want. I'm disappointed in your installer - he gave you the worst possible advice. What happened is signal overload to your tv. I'm thinking that ch. 17 is still overloading your tuner. You could try knocking the signal down by adding a splitter to the cable (cheap to try) or pointing your antenna slightly away from the transmt site.

It is also possible that you have strong reflections from the ground or nearby structures that set up "hot" and "cold" zones in the space above your house. There is a tutorial at hvprimer.com that explains this. Anyway, if trying to weaken reception doesn't help, then you will have to raise/lower your antenna or move the mounting location to get out of the cold zone for 17.

Good luck!

I am disappointed in the installer also. Signal amplifiers are not the magic cure all. Many "installers" do not have a clue. . And do not even want to have a clue. . It's all a real head shaker for me.

[Tower Guy]

Originally Posted by Jnktwnman

My installer has said that I should try an amplifier at the set -

That's bad advice from the installer. It makes me wonder if the antenna is even aimed properly.

The antenna is fine for your location. No preamp is necessary.

If the UHF stations that you're having trouble with are WNJS, WMCN, and WNJT, they are not the same direction as the Philly stations. You can solve that problem with a second antenna and an A/B switch or a rotor on your current antenna.

Of course the advice to check your connections is also valid.

[Jnktwnman]

Thanks to everyone. Interesting comments about amplifiers not necessary for my area (very, very close to Philadelphia). I'll give up on trying different amps from this point on. That seems to explain why my problem seemed to get worse with the amplifier attached.

By the way all other channels (mostly VHF) come in fantastic just about 100% in quality all the time. As far as signal strength and intensity for these 2 nearby Philadelphia UHF channels (Fox and MyPhl) for some reason at times the intensity & quality are at 100 % and everything is ok. But when I get a lot of pixellation the signal intensity and quality drift all over from ~70% on down - and, of course, when I get 'bad signal' the intensity and quality both dip to 0. Why such discrepancies ? I know that my nearby neighbor is a local fireman and many times I hear a radio "scanner". Should I run a test with him to see if my problem only occurs when he runs the scanner ?

In any case, to answer Teleview's questions some more, there are 3 TVs thru the house connected to this antenna, via splitters with no other computer or radio equipment "stacked". All connections appear to be solid -again all the VHF stations are solid reception, it's just these few UHF stations (Ch.17 & 29) that all too frequently (like, when trying to watch the Phillies) that they pixellate like mad and drop the signal altogether for a few seconds. It's this inconsistency that drives me mad and makes me think holds the key.

Thanks for any additional tips you may have ?

I have been doing telecommunications for many years and I know that when the Truth Is Not Presented Up Front!!! . . 3 Tv's through out the house , connected Via Splitters , The 'Via Splitters' is a tell tale sign of problems. One splitter connected to an other splitter connected to an other splitter connected to an other splitter connected to an other splitter connected to another splitter and etc.. . . . ONE 3 Way Splitter with the with the input connected to the antenna and each of the 3 out puts will have a Single and Continues RG-6 coax cable run to each Tv location. . http://www.solidsignal.com . . the Channel Master CM3213.. Next look at the Virtual and Real Channels , WTXF Virtual 29 is Real Channel UHF 42. . Is the Tv antenna aimed correctly at the Tv Transmitters?? Or is the UHF end and UHF reflector turned in the oppisit direction of the transmitters north and west of Philadelphida. . And what about the double rescan at dtv.gov. . GET YOUR SITUTAION CORRECTED FIRST !!!!. . I believe that you are still leaving out some facts about your situtation. . CONNECT -->ONE<-- TV TO THE ANTENNA WITH NO SPLITTERS , Now what does 17 and 42 look like???? .. And a scanner is a device that receives but does not transmit. .

[Dave Loudin]

I didn't realize that you already had splitters in the line (good catch, teleview). Believe it or not, but a splitter does not transfer power completely from input to outputs. An unavoidable property of radio/TV connections is reflections. Some power is always reflected back to the source.

You have very strong signals, which amplify the effects of reflections and mismatches and loose connections. Teleview's recommendation of simplifying your setup is sound. Directly connect to one tv and see what you get. If you still have problems, then twiddling with the antenna's aim first, then adjust the antenna's height.

Once you're set with one tv, go with the splitter teleview recommended. It will be far better to run extra cable then have a bunch of connections.

Good luck!

It's not that it's a good catch. I have been answering questions for a long time now and I know that MANY of the question askers with hold information , they think that some how some way something Magic is going to happen. They think that withholding the Truth is a good thing to do and that I will not find out the truth. Read all of the past question askers and you will see a common thread running through them , withholding information and dancing around the truth. . The truth is this question asker could have stated the information up front but did not , I went along with the game , knowing that there is more to it. . If you read my past interactions with the question askers , you will see that sometimes I ask for the information that they are not providing in the beginning and some times I keep reeling out more rope. . Here is a question , Is this Question asker telling the complete Truth about the 'Installer'?

[Dave Loudin]

Teleview,
Please remember that these are people not familiar with RF for the most part, and they do not know what they need to tell. It's not a grand conspiracy to withhold truth. Your tone as it is written borders on embarrassing the person seeking help, and that will chase people away.

Ultimately, this should be an educational experience. I know I keep learning all the time.

[No static at all]

Originally Posted by Dave Loudin

Ultimately, this should be an educational experience. I know I keep learning all the time.

Well said Dave, Thanks

[Billiam]

Yes, a pre amp is not always a requirement for obtaining a strong or reliable signal.

As evidence. I live 40 miles from Kansas City. I found that with a CB (Channel Bastard) 4221 HD antenna (no pre amp) mounted on a chair in the inside front of my home I am able to get reliable reception for all but one KC station and a station from Sedalia which is 75 miles away. However, when I mounted a CB 4228 (original model) and Antennacraft U8000 on the roof I found that I could not get reliable reception of most signals even with the pre amp. I then switched to a Antennacraft MXU59 on the roof and found I could get every KC signal at 80 to 90% and the Sedalia signal is watchable and reliable if the antenna is pointed in that direction.

[Billiam]

Originally Posted by Dave Loudin

Teleview,
Please remember that these are people not familiar with RF for the most part, and they do not know what they need to tell. It's not a grand conspiracy to withhold truth. Your tone as it is written borders on embarrassing the person seeking help, and that will chase people away.

Ultimately, this should be an educational experience. I know I keep learning all the time.

Judging by the tone and content of his post, I think he's with the "Thought Police".

[Dave Loudin]

No, I truly believe that he wants to help and is thoroughly disgusted with how far we've gone from people having enough basic information to work with. He's been trying to get people to focus on first principles and build from there. To put a bow on this drift, think about what you heard, or did not hear, from anybody - local affiliates, manufacturers, the FCC, etc. - concerning the move to digital TV. It was as if no one wanted to say anything that could bias the market from any solution, whether it worked or not.

Let's get back to the task at hand here. To recap:

1) the TVFool report showed tremendously strong signals and a clear view (terrain-wise) of the transmitting site.

2) several channels were dropping out - it just so happens that one is his strongest

3) adding a pre-amp didn't help

4) the signal gets split a couple of times along the way

Two things initially were in play - overloading the tuner and multipath reception conditions. We suggested "desesitizing" by first aiming the antenna off-target a little (which could solve multipath, too) then second adding a splitter to the line to knock the signal down some. Turns out there were already splitters in the line, and with multiple splitters, the inevitable signal reflections (something a layman would not know about) could cause problems.

The next step is to go to the least complicated configuration and build from there.

[Jnktwnman]

Thanks again guys. You are right, this is an education for me and I appreciate it. I especially appreciate learning that my neighbor's scanner is not an issue and that having a pre-amp is totally unnecessary in my situation.

As far as the splitters go, the installers put them in, and as far as I knew, that was how you got to multiple TVs. I hired the installers because I had no idea what to do. But in the installers' defense - when they installed (and I was here watching them) they tweaked the antenna for a long while as they kept checking the quality and intensity of the various signals. At that time, and, again, many times after, ALL of the channels (VHF & UHF) seemed to come in perfectly.

It was a few weeks after the install that I noticed that the UHF channels (17 & 29) that I watch sometimes, would pixellate and completely drop signal. All of the VHF channels continue to come in perfectly. And sometimes even these UHF channels (17 & 29) come in perfectly with no pixellation or dropped signal. But, way too often for good TV viewing, these channels (17 & 29) and only these channels pixellate and drop signal. (I have to admit I don't often watch the other UHF stations).

From what I can gather from the threads, I think that the easiest and first thing for me to try and test is by disconnecting the other outputs from the very 1st splitter that comes off of the antenna. With a ladder I can reach that and, I believe, handle it (at least for a test). That will be a great test of counteracting what I think you are calling the "reflection" issue.

2nd, if "reflection" does not seem to be the problem, then I will definitely have to call the installers back to help with re-adjusting the antenna according to you guys and your advice.

Thanks again for hanging in there with me and pointing me in the right directions.

[Billiam]

Might be a seasonal problem. From what I understand, when the leaves are off the trees you will likely have better reception of HDTV signals. When the leaves start to grow then reception is diminished. This may explain why you were getting better reception at a previous time than in recent weeks.

[Dave Loudin]

You are correct. I was just helping someone on another forum who lives within 7 miles of the tranmitters, but is shadowed by a hill. The recent heat wave put a big hurt on reception conditions. However, this is a case of very strong signals and real line-of-sight paths. The pixellation in this case is due to multipath interference, reflections in the cable run, or signal overload.

If you have to call the installer back, have him read this and this from hdtvprimer.com. Those have been my primary sources for trying to figure out what's happening.

Good luck, and BE CAREFUL!

DO NOT put the 3 way splitter at some Monkey Swinging Death Defining place in or on the house. . Put the 3 way splitter at a place that it is Easy to get at.

[Jnktwnman]

The installers had installed all of these splitters connected together. What I'll call #1 splitter is down from the antenna on the outside of the house at the 2nd floor to a 2nd floor converter box & TV. #2 splitter is in the basement connected to a digital converter box & TV. #3 splitter is on the 1st floor on the wire split that runs along the basement ceiling up to my 1st floor converter box & TV.

Since I am testing the "reflection" issue, I was going to get on the ladder and disconnect the #1 split off, and then disconnect the #2 split off, thereby testing the longest run of wire to the #3 connection and TV.

However for my test, can I simply disconnect any 2 of the splits at the converter/TV no matter where they are - this leaves what I (as a lay person) might call "non-terminated" antenna wire out there. This saves me from going up on the ladder for a test.
I have actually done this (that is, disconnected the wire from converter/TV#1 and from converter/TV#2 and it seemed to help a bit in a short test. I am not totally convinced that this is the answer until I see how it works over a couple more days of time.

Is this a valid test (with these, as I say, un-terminated cables hanging out there) or should I disconnect from the actual splitters themselves, leaving one long contiguous run (albeit with splitters as connectors in the long run) ?

Thanks again for all the input..

[kb2fzq]

Originally Posted by Jnktwnman

The installers had installed all of these splitters connected together. What I'll call #1 splitter is down from the antenna on the outside of the house at the 2nd floor to a 2nd floor converter box & TV. #2 splitter is in the basement connected to a digital converter box & TV. #3 splitter is on the 1st floor on the wire split that runs along the basement ceiling up to my 1st floor converter box & TV.

Since I am testing the "reflection" issue, I was going to get on the ladder and disconnect the #1 split off, and then disconnect the #2 split off, thereby testing the longest run of wire to the #3 connection and TV.

However for my test, can I simply disconnect any 2 of the splits at the converter/TV no matter where they are - this leaves what I (as a lay person) might call "non-terminated" antenna wire out there. This saves me from going up on the ladder for a test.
I have actually done this (that is, disconnected the wire from converter/TV#1 and from converter/TV#2 and it seemed to help a bit in a short test. I am not totally convinced that this is the answer until I see how it works over a couple more days of time.

Is this a valid test (with these, as I say, un-terminated cables hanging out there) or should I disconnect from the actual splitters themselves, leaving one long contiguous run (albeit with splitters as connectors in the long run) ?

Thanks again for all the input..

Personally, so as to create a base line condition, I would go to Radio Shack and get a new 25 foot run of RG6 coax and connect it directly from the antenna to ONE TV, probably the TV that is easiestly accessed, thru a window if necessary, with no pre-amps in line. Do a complete rescan on that one TV. This will tell you what stations will come in and signal strengths without splitters and pre-amps and numerous TV's, just the raw signals to one TV. I'd write down the signal strengths. I'd also get 3 female to female f-connector couplers. After you have the base line, go back to the current coax, one by one, add another TV on the current coax setup, using the couplers instead of splitters on the TV sections you won't be connecting, and replacing the coupler with a splitter as you add TV's, noting how the signals change as the TV's are added....eventually, you will see a pattern as the TV's are added. You may find that all the TV's can't be added because of the loss from the splitters and/or coax lengths....typically, the farthest away, most split off TV should have the weakest signals at the TV....just my 2 cents...