Intereference Question

[hoot550]

I am hoping someone can tell me if I'm on the right track in diagnosing this problem. I recently upgraded my system to a 4DTV DSR-922. This means that I've now go subscription programming and therefore tend to watch more tv instead of just scanning.

Over the past couple of days, I noticed that on the digital channels, they would go black out, pixelate then return to normal. I thought maybe it was not quite peaked, so I went through that process again, and have good signal all across the arc. The next day, it was windy and my system tends to move just a bit (actuator needs replaced when I have some extra $$) so I just let it go. Today is a nice calm day, and it's doing it again.

So I tune over to an analog station, and there's a burst of intereference about every 11 seconds, which you can see on the analog channels. On some of the digital channels, I can only assume this is what's causing the dropout and pixelation at about the same interval.

It's worth noting this only happens during the daytime. I live in the country and my nearest neighbor is about the equivalent of two blocks away. The nearest power line is probably about 1/4 mile away. I believe there is a telephone line that runs about 10 feet away and under the dish.

Now, my LNB and the dish are older (probably circa 1990). I read in a forum where someone posted a setup almost exactly like mine and someone said the LNB would be a bit "noisy" for digital. I believe this one is 30 degree, but the markings are worn off of it. Would a newer LNB possibly end this problem?

I never noticed this before when I would watch analog feeds once in a while during the day on my old receiver. However, the kids are home for summer and it's been hot, so the TV has been on more during the day. My Toshiba TRX 2200 had a "TI Filter" setting which I had turned on, so maybe that's why.

Any thoughts on a possible solution before I try a new LNB?

 

[sergei]

Sounds like you may have TI (Terrestrial Interference)...MAYBE

One possibly do you have an airport near you, one that only lands planes in the daytime and your in the fly path and what your seeing is the radar sweep or maybe a microwave towers inline with your dish.

Does the problem change if you change dish position?

Is this problem on all satellites?

Another is you LNB is failing and is being affected by daytime temperature or is weak enough to be affected by outside source.
Do you still have your old receiver, if so put it back in and check the analog channel..see if it's gone.

Just a couple of thoughts.....

 

[tvropro]

Could be AWACS from military aircraft. This has been a problem on some area's since 911.

 

[Tower Guy]

I am hoping someone can tell me if I'm on the right track in diagnosing this problem. So I tune over to an analog station, and there's a burst of intereference about every 11 seconds, which you can see on the analog channels.

Any thoughts on a possible solution before I try a new LNB?

A low phase noise LNB won't fix your problem. You are likely to have radar interference. The rotation rate of NEXRAD radar is about 9-10 seconds.

http://www2.inmh.ro/uploads/wsr98d.pdf

Are you line of sight to any fixed radar installations such as NEXRAD?

If it is radar interference the two solutions are shielding or filtering.

To shield the dish, 1/4" hardware cloth can block the radar. To filter the LNB, install a radar filter between the feed horn and the LNB.

 

[hoot550]

Thanks for the tips everyone. Too bad I can't seem to spell interference in the subject, though.

These are all within the realm of possibility. I should have mentioned that it is all across the arc and bumping the dish east/west or adjusting skew has no effect on it.

After I posted I thought of a good description that may be something familiar. Back when I was a kid and we got over the air broadcast only, someone would switch on a vacuum or another appliance in the house and you'd get static across the screen. It looks like that, but it's only for a split second.

The nearest airport is about 60 miles away. I'm not sure about NEXRAD, but it seems like there's a tower about 40 miles away. Since it's as flat as Kansas out here, just about anything a few feet off the ground is line of sight. That seems to make the most sense especially with the timing of it.

Cell towers are all quite a distance and there is one tower about three miles away that a radio guy I know owns. I may see if he's fooling around with something.

I'll hook up my old receiver and test that out. I'll let you know what I find.

 

[Lak7]

If I remember, there is a TI Filter option in one of the 4DTV's Menu.

 

[sergei]

I checked my 920 for a ti filers couldn't find one, maybe the 922 has one added to its menu since its a new model.
Here's something else to try until microwave or radar can be ruled for sure as the source of the interference. Since moving dish has no affect let's have you try something else to help rule thing out. It may be your picking up outside electrical interference and heres some ideas on checking that.

1) Does this show up at all on any of your TV local channels .
2) If you have outside antenna into 922 remove it and see if that helps.
3) Try removing all the dish wiring to the 922 and see what happens..replace the outside antenna.
4) Maybe what your seeing is a TV problem so can you try another TV

Have you been able to map the times this starts and ends, does this start and stop at the same time?

 

[truckracer]

I get loads of TI on some days and yes I can see the "flicker of snow" on the analog C-band.
Some days my HBO on G1 is not watchable. Yes it is about every 11 seconds or so. I have timed it numerous events.

You definitely have TI and probably not much to do about it.
There is a waveguide choke you can buy that bolts in between your C-band lnb and the feedhorn. These also harm you desired signal to some degree and they are expensive.

I have heard AWACS can knock out C-band. I also have a weather radar downtown just a few blocks away not to mention I live near the River where barges and boats have High powered radars as well. Its a real PIA.

One reason I miss the Hits feeds from KU X4. I thought of subbing HBO/MAX from X4 back when it was on the air to eliminate my TI dropouts on the movies. I never have this problem late at night.

There is also something going on that keeps my HBO and MAX channels signal quality lower than normal some days. On my 10 dish I used to get 90% QUALITY on those channels from G1 (dsr-905 sidecar). Now some days I can only get 60% quality but a good lock.
It fluctuates up and down and you can watch the number change.

Today I am at full strength. but it will go down again. Its the same on both my c-band dishes so that rules out technical problems.

 

[hoot550]

I have been playing with this all morning, and here are my findings. I agree with truckracer that this is TI of some sort.

The first thing I did was put my old receiver on this as soon as it started this morning. I could see a little flicker on the analog channels, so it was definitely not the 922 itself. However, at Skyvision's suggestion, I did ground the chassis of the receiver, but it didn't help.

I switched wires around, and even removed the slaved dvb receiver. As I was doing that, I thought about checking that setup. I have a separate ku hh dish. Sure enough, that signal is breaking up at regular intervals on some channels. It's not as frequent, but it is happening.

As I was typing this up, I was talking to a family member who is having the same problem with directv, as are several of her friends with dish and directv. So something is going on out here in the boonies.

As always, thanks for all of your help!

 

[sergei]

You can try putting your hand over the LNB on either dish and see if the TI stops,
that might help telling you if it's IN bound TI or your looking at whats call Out of Band TI

Has any new towers of any kind been installed in your area, you should be able to see it?

 

[hoot550]

You can try putting your hand over the LNB on either dish and see if the TI stops,
that might help telling you if it's IN bound TI or your looking at whats call Out of Band TI

Has any new towers of any kind been installed in your area, you should be able to see it?

That's a good idea, I'll try that.

I don't believe there is are any new towers around here. That doesn't mean someone did not add on or change something on the existing ones, though. I'll let you know if I find out anything.

 

[tvropro]

As I was typing this up, I was talking to a family member who is having the same problem with directv, as are several of her friends with dish and directv. So something is going on out here in the boonies.

Now that's a twist, TI normally affects c band not ku. Direct & Dish are on the upper edge of ku freqs. It may be some kind of front end overload that is killing the block down conversion or is very broadbanded or causing spurious harmonics all over the place. I've seen ingress TI from powerlines get into my cable many years ago. I ended up burying my run from the dish to the house this helped quite a bit.

 

[hoot550]

Now that's a twist, TI normally affects c band not ku. Direct & Dish are on the upper edge of ku freqs. It may be some kind of front end overload that is killing the block down conversion or is very broadbanded or causing spurious harmonics all over the place. I've seen ingress TI from powerlines get into my cable many years ago. I ended up burying my run from the dish to the house this helped quite a bit.

That was my understanding too. I'm somewhat of a newbie to this. That's why I didn't even think to check my dedicated ku setup. Sure enough though, I can watch the signal drop off at regular intervals. It's not as noticeable, but it's definitely there. I've confirmed with some others I know with dish and direct that it's happening to them as well.

E.T. is phoning home or something.

 

[Hermitman]

If you're out in a rural area, do you or any of your neighbors have an electric fence? If an electric fence isn't set up properly or the charger is malfunctioning, you can get a heck of an EM pulse being sent out at regular intervals. Just a thought. Good luck.

 

[sergei]

Hermitman post commented about living in a rural area and that makes me ask if you live in subdivision and if the neighbors you mentioned live in the same area or down the road, and are they on the same power lines. Next question are they buried or overhead lines.

 

[hoot550]

Hermitman post commented about living in a rural area and that makes me ask if you live in subdivision and if the neighbors you mentioned live in the same area or down the road, and are they on the same power lines. Next question are they buried or overhead lines.

They are overhead lines. Now, by rural, I mean farm type rural. We live on the outside of the "town" which has, in total, about 20 houses. There are probably more people in a Wal-Mart on any given Saturday than live in this entire zip code.

I'm not sure if it's related or not, but last night several people in the community lost power for no apparent reason. There was a storm in the area, but it was miles away from where the power went out. This morning, I have been watching the morning news and have not had one bit of interference. So, I'm crossing my fingers that these two incidents are related. Maybe some electric company equipment in the area was malfunctioning and causing it.

I'll keep you posted...

 

[sergei]

Hopefully your problem is gone because its not easy to find and fix this type of problem, if it does come back, you and the neighbors having problems need to get in touch with your power company and have them check their lines. They have the test equipment to look for line problems, grounding, etc., it just getting them to omit they have a problem with their stuff.

Did you ever figure out a time frame when this happened, was it only during daytime or all the time?

 

[truckracer]

My neighbors lawn mower will cause TI on c-band digital. I guess its the ignition system causing emp. I can have c-band channel on, when he gets near my dish on the other side of the fence I can see it blip out.

 

[sergei]

Hopefully he only cuts the grass once a week..otherwise what a pain