OTA reception problem & backfeed possibility?

[sam_gordon]

One annoyance and one "how can I?"...

I've included a signal flow drawing of my system. The OTA antenna is in the attic, the three dotted line boxes are the basement, the living room (VIP211), and the bedroom (VIP612).

Problem #1) When watching (and sometimes recording) OTA on the 612, "loss of signal" message will come up. This happens on multiple channels. It is not consistent. Sometimes I can watch a show with no problems, others are unwatchable. All the channels show between a 70-90 signal strength on the 612. I'm pretty sure when I get the loss of signal message, the signal strength drops to 0. I *KNOW* when I lose the signal, BOTH TVs are getting the signal just fine. The RF line from the antenna goes through a signal block and is grounded to house ground. Is this just a problem with the 612? I've tried putting RF pads at the OTA input on the 612 (thinking 'too much' signal). Any ideas?

#2) Can I 'backfeed' the RF signal from the 612 so I can watch DVR shows on the living room TV? Yes, I know they'll be SD.

 

[highdefjeff]

One annoyance and one "how can I?"...

I've included a signal flow drawing of my system. The OTA antenna is in the attic, the three dotted line boxes are the basement, the living room (VIP211), and the bedroom (VIP612).

Problem #1) When watching (and sometimes recording) OTA on the 612, "loss of signal" message will come up. This happens on multiple channels. It is not consistent. Sometimes I can watch a show with no problems, others are unwatchable. All the channels show between a 70-90 signal strength on the 612. I'm pretty sure when I get the loss of signal message, the signal strength drops to 0. I *KNOW* when I lose the signal, BOTH TVs are getting the signal just fine. The RF line from the antenna goes through a signal block and is grounded to house ground. Is this just a problem with the 612? I've tried putting RF pads at the OTA input on the 612 (thinking 'too much' signal). Any ideas?

#2) Can I 'backfeed' the RF signal from the 612 so I can watch DVR shows on the living room TV? Yes, I know they'll be SD.

I like the nice picture!

Problem 1:

I would first remove the splitter between the diplexer and the 612. Run the OTA directly to the 612. I would also replace the set of diplexers that are there. Diplexors of several types will often fail within 6 to 12 months, usually on the non-powered side. Just like splitters, they will sometimes be intermittent in their performance.

P.S. Have you tried without the amplifier? And always check all connections and fittings for quality.

Problem 2:

Yes, but, I would expect additional problems.

 

[whatchel1]

OTA drop out

Nice block diagram. What is happening is the 612 isn't dropping sat signal. The OTA is losing signal. This will make the 612 drop the sat signal. This has been something that has cropped up alot lately in the threads. Try getting rid of the RF splitter and see if it goes away (highdefjeff said as much). I'm just reinforcing that statement and if that helps then your next step will be to get a better signal from OTA. I'm not a big fan of having the OTA inside the attic. You will be losing 30 to 50% of your signal right there. Add possible mulitpath to that and it could be the major problem.

 

[sam_gordon]

My problem is I need to keep the straight OTA feed to the TV. Because of work, I need to be able to see the OTA signal with no in between box. BTW, I don't have it on the drawing, but there is a 10db RF pad on the OTA input to the 612. I think before I had that pad all the stations were coming in with 100 signal strength (my Fox & PBS affils are ~5 miles away, ABC, NBC, and CBS are all ~16 miles away).

So I guess the question is what should the OTA signal strength be (ideally)?

 

[highdefjeff]

My problem is I need to keep the straight OTA feed to the TV. Because of work, I need to be able to see the OTA signal with no in between box.Okay, then still check connections and replace the splitter and diplexers. They are relatively inexpensive items and their replacement would be my next step in troubleshooting. Besides, that gives me the opportunity to check for any stray shielding braid, or bit of foil that might be touching (or near) the center conductor. This is also the time to check that all of the center conductors are at least 1/16th of an inch beyond flush of the connector (not longer than 1/8th inch beyond). If new splitter and diplexers make no difference, then save the old ones for when there is a problem. This won't be all that is needed, though... BTW, I don't have it on the drawing, but there is a 10db RF pad on the OTA input to the 612. I think before I had that pad all the stations were coming in with 100 signal strength (my Fox & PBS affils are ~5 miles away, ABC, NBC, and CBS are all ~16 miles away). So here is what you do. You are only a couple miles from the stations, so remove the amplifier. And, without the amplifier, you won't need the 10 db pad. Remove the pad. (The pad essentially adds 10 db of noise. The amplifier both ADDS noise but it then it also will amplify the noise along with the signal. The net result is lower SNR (signal to noise ratio) which translates into more errors per bit. Hopefully the increase in signal quality will be enough to re-gain your stations at a level of consistent reception. You need to do this first, then check performance. If your OTA is overloaded, then add back some attenuation, by changing the alignment of your antenna. But make sure to remove the amplifier and connect the wires directly, using an F-81 barrel connector (3Ghz-blue center). If you leave the amplifier in, it still adds noise - even when turned off or unplugged.

So I guess the question is what should the OTA signal strength be (ideally)?

And the answer to the question is: As high as possible without overloading the receiver.

 

[whatchel1]

Ideally?

My problem is I need to keep the straight OTA feed to the TV. Because of work, I need to be able to see the OTA signal with no in between box. BTW, I don't have it on the drawing, but there is a 10db RF pad on the OTA input to the 612. I think before I had that pad all the stations were coming in with 100 signal strength (my Fox & PBS affils are ~5 miles away, ABC, NBC, and CBS are all ~16 miles away).

So I guess the question is what should the OTA signal strength be (ideally)?

Don't know what Ideal is but pretty much what I've seen is less than 80 you could be looking at problems. 100 doesn't seem to hurt anything. I have one that is 88 and one that is 100 others are in between. Just used some attenuators in line and below 80 & picture wentout.

 

[highdefjeff]

My problem is I need to keep the straight OTA feed to the TV. Because of work, I need to be able to see the OTA signal with no in between box. BTW, I don't have it on the drawing, but there is a 10db RF pad on the OTA input to the 612. I think before I had that pad all the stations were coming in with 100 signal strength (my Fox & PBS affils are ~5 miles away, ABC, NBC, and CBS are all ~16 miles away).

So I guess the question is what should the OTA signal strength be (ideally)?

Sam, I am going to pose an alternate solution.

Due to your proximity to the towers, I would expect that MOST indoor antennae would be quite adequate. So, why don't you put your TV that need's direct feed on an indoor antenna, or all of them for that matter. Then if you wanted to use diplexers to get DVR in the other room, it would probably work.

Just a thought. Here's a a link to some homemade antenna that would work for you. Grabbit Ears aren't needed, probably just a two-bay hoverman (whisker) design would do. There's a link to a video for a 4 bay which is too much.

GrabBit Ears - The best indoor antenna!

 

[whatchel1]

Indoor ant yuk.

If you are having problems w/in attic antenna then indoor is even less likely to work correctly.

 

[sam_gordon]

I'll try to pull the amp and pad out and see what happens. I wanted the amp to make up for line loss/splits. Also, the attic mounted antenna is fine, on two separate TVs (two different manufacturers at that). It's only the 612 that sometimes "chokes" on the signal. If I still have problems after that I'll try changing the splitters, then the diplexers.

 

[llzel]

612 handles OTA terribly. 612 receivers weren't one of Dish's finest units. I would double check that the OTA ground and add aDC block at the 612

 

[highdefjeff]

I'll try to pull the amp and pad out and see what happens. I wanted the amp to make up for line loss/splits. Also, the attic mounted antenna is fine, on two separate TVs (two different manufacturers at that). It's only the 612 that sometimes "chokes" on the signal. If I still have problems after that I'll try changing the splitters, then the diplexers.

llzel is correct about 612 tuners being far less than special.

But maybe I can shed some light on amplifiers in relation to splitters/diplexers and signal quality.

An amplifier is used to compensate for line loss (as you say). The line loss that is referred to, comes from long cable runs that attenuate (reduce) signal. Line loss isn't the attenuation of the signal that accompanies the addition of a barrel connector or splitter. If you have an attic mounted antenna, it is unlikely that you have cable runs long enough to need to use an amplifier. (And with your proximity to the towers, you still shouldn't need the amplifier.)

An amplifier is not used to correct poor signal or overcome noise. If you are going to use an amplifier, you need to have good signal to noise ratio (SNR), first, because the amp will increase both the signal strength and the noise - plus it adds more noise of its own. If you have a poor quality signal (too much noise) and you amplify it, you get more poor quality signal.

So, if you have low signal strength, then amplify. If you have high noise, avoid amplification. In your case, you have a high noise environment so amplification is actually adversely affecting your signal quality.

 

[rcbridge]

Do you have DC blocking on the diplex filters OTA side?

 

[sam_gordon]

No DC blocks installed anywhere.

 

[rcbridge]

I would put them in on the OTA side only.

 

[highdefjeff]

If you are having problems w/in attic antenna then indoor is even less likely to work correctly.

I agree in cases where signal is too weak. Weak signal doesn't sound like Sam's issue. His sounds like too much signal and too much noise.

In Sam's case, he states:

"I think before I had that pad all the stations were coming in with 100 signal strength"

This suggests to me that he was overdriving the receiver's tuner, or he wouldn't have attempted to reduce the signal.

Proximity to towers using an attic antenna also suggests too much signal.

Amplification points the same way.

So, in his case, I think he took "enough" or too much signal and then amplified it, making it too much for the 612, then attenuated the signal. The amplification process and the attenuation (within the scope of his already high noise install of splitting, amplifying, diplexing) has caused increased noise problems in the signal. The better tuners in the TVs can still handle it (dirty signal) and the 612 can't.

If the suspect problems are both signal and noise that are too high (as I suspect) a smaller, separate, antenna could be used to provide a cleaner, better quality signal.

This remains to be seen, though. The trouble shooting process would be as previously suggested...clean up the signal by starting without amp and attenuation, and checking connections/replacing diplexers and splitters. Then see what the signal is and how it well it works or doesn't on the 612.

Without knowing what the results are of that process, there is no way to determine his actual solution or even the next step (which is why I offered a possible alternate solution).

Good trouble shooting is a logical, orderly process that continues in steps until the resolution is found. Sometimes you know exactly where the problem is, and sometimes you've got to find it.

 

[sam_gordon]

Jeff may be right on the over amplification. I used to have access to a signal meter for analog OTA, DTV OTA, and cable, but now can't find it. I'm going to try removing the amp and pad and see what happens, just haven't gotten around to it yet.

 

[whatchel1]

What's the amp

Jeff may be right on the over amplification. I used to have access to a signal meter for analog OTA, DTV OTA, and cable, but now can't find it. I'm going to try removing the amp and pad and see what happens, just haven't gotten around to it yet.

What's the amount of amplification that you have in line. Right now by looking at the block diagram It's looking like you are 10 db att to the 612 (roughly). I have a signal meter and use a pad on mine. It came w/my DVR to be used in line if the UHF remote input gets over loaded. Don't need it there & do need it in the OTA line.

 

[sam_gordon]

What's the amount of amplification that you have in line. Right now by looking at the block diagram It's looking like you are 10 db att to the 612 (roughly). I have a signal meter and use a pad on mine. It came w/my DVR to be used in line if the UHF remote input gets over loaded. Don't need it there & do need it in the OTA line.

Would you believe I don't know? It's a Winegard DA815. It's one I got from work that used to be part of our house CATV system.

 

[whatchel1]

15 db

Would you believe I don't know? It's a Winegard DA815. It's one I got from work that used to be part of our house CATV system.

I think that is a 15 db amp. Not sur e of the freq it handles though couldn't fine specs on it. Does it have any adj controls on it?

 

[sam_gordon]

Update: pulled the pad/amp off the line. I should have measured before I did so, but current strength measurements

612: 75-90 depending on the station
TV2 (connected to 612): 100 on all stations
TV1 (connected to 211): 70 on some stations, 100 on others.

Now it's a waiting game. I don't watch a lot of OTA, so we'll just have to see what happens.

Thanks for the help guys.