question regarding overamplification

[mulliganman]

I brought out some guys to help me as I was changing my system a bit to incorporate a Tivo whole home setup and using Moca (so that my antenna signal is only going to a single four tuner Tivo Roamio). I have two Mini's in place that "borrow" a tuner from the Roamio when in use on two other televisions.

Now that I have described my setup here is the question. As we were setting this up, an installer wanted to see what the signal strength for a channel would be on my one tuner TV. It was at 98% but on the Tivo somewhere around 50-52%. He said I could not add an amp to bring up the signal strength of that or other channels for risk of overampage. Is that correct?

[mulliganman]

Here is what my signals look like: http://www.tvfool.com/?option=com_wr...d24362e8886d03

Using a 91XG and an Antennas Direct to get all the green signals and Fox.

[ADTech]

Unless you're having actual problems with reception, do not waste time and effort just chasing numbers on the Tivo's screen.

[mulliganman]

Originally Posted by ADTech

Unless you're having actual problems with reception, do not waste time and effort just chasing numbers on the Tivo's screen.

Thank you for replying! Yeah, I don't want to spend time chasing numbers on the Tivo screen. What they said they were doing after getting the Moca network setup for Tivo was "balancing" the signals going to my Roamio (by the time they were done the signal strength had dropped some on most of my channels according to the Tivo signal strength measure). I had been experiencing some of what I might describe as "cutting out" on some stations prior to today. Still seen it a couple times on Fox this evening. I really was just wondering for my own curiosity since I thought because the signal strength numbers were lower I could "afford" some additional amplification and hopefully clear up some of the aforementioned problems.

[ZippyTheChicken]

your tv fool is very very good for the stations within 20 miles but you do have one conflict on channel 17 an amp might make both unviewable

If you are only trying to get those first 20 mile stations an omnidirectional with an internal amp would do well... if you are trying to keep the locals and bring in others then any chanel with a C next to it could get blown out by another.....

also for sake of conversation over amping can blow out a tv tuner over time

[ADTech]

There is no risk of any physical damage to a tuner from using a preamplifier. The power levels are too low. If the signals are over-amplified, reception will be lost, but the condition lasts only as long as the overload condition. Again, NO PHYSICAL DAMAGE.

There is no risk of conflict on channel 17, either. The F/B ratios of the antennas will easily prevent any issues there. Even if there was a conflict, you'd lose Branson's tourist channel and a repeater for Larry Rice's New Life Evangelistic center, assuming both are actually on the air.

the signal strength numbers were lower I could "afford" some additional amplification

So called "signal strength" indicators usually are not an indicator of signal power (they indicate decodability or error rate instead) and amplifiers can only increase the power level of signals at a small cost of signal to noise ratio. I haven't played with a Roamio yet, but its predecessor, the Premiere, had an advanced diagnostics menu that gave SNR readings and error rates. Perhaps the Roamio kept this feature. In any event, there is no use in trying to get above a certain threshold until you know what the minimum threshold for a specific make and model of a tuner might be. Perhaps the Roamio is a "20" or a "30" or a "55", or whatever, I don't know.

Maybe some modest amplification might help, but there's a whole bunch of information that hasn't been provided that is needed to analyze the distribution system.

[mulliganman]

Originally Posted by ADTech

So called "signal strength" indicators usually are not an indicator of signal power (they indicate decodability or error rate instead) and amplifiers can only increase the power level of signals at a small cost of signal to noise ratio. I haven't played with a Roamio yet, but its predecessor, the Premiere, had an advanced diagnostics menu that gave SNR readings and error rates. Perhaps the Roamio kept this feature. In any event, there is no use in trying to get above a certain threshold until you know what the minimum threshold for a specific make and model of a tuner might be. Perhaps the Roamio is a "20" or a "30" or a "55", or whatever, I don't know.

Maybe some modest amplification might help, but there's a whole bunch of information that hasn't been provided that is needed to analyze the distribution system.

It may sound strange but I am in a "wait and see" and "trying to confirm this is the best setup for picture quality/no picture issues etc." I attached a jpeg file of what my setup looks like after they got done. What the diagram does not show is a Tinlee AC7 combiner for Channel 49 Fox that they took out (for whatever reason they thought is was causing a loss of signal). My main purpose for bringing out the help was to create the moca network that is separate from the Tv signal network. But, I was wanting them to explore whether some additional amplification could help clear up some of the picture issues I had been seeing at times like small cutting out of the picture I have been seeing on the screen at times (the system had to be adjusted anyway to just send the TV signal to the Roamio connected television).

The Roamio has a "signal strength" meter that can be accessed as well as a "DVR diagnostics" menu. The DVR diagnostics goes beyond just signal strength and gives SNR and other information. So, I am guessing the information is the same as the Premiere. If you could tell me something to check for, I can do that.

I would like to go back to my original question about whether they or right regarding the amplification and thoughts on the setup in general.

ADTech, have I provided enough information to better analyze the situation?

[mulliganman]

Anyone got an opinion siince i posted the diagram?

[rabbit73]

I saw your last post before you edited it.

Most of the people that help with reception problems volunteer their time. Those that are paid to do it probably want to do something else in their free time.

There were probably many people that read your thread, but couldn't think of a suggestion that would help you.

In my case, I'm the care-giver for my wife who is not well, so I come here to forget about my problems.

You probably saw my previous post in your e-mail. I deleted it because I didn't have the time then to make a good analysis of your problem.

He said I could not add an amp to bring up the signal strength of that or other channels for risk of overampage. Is that correct?

If he was talking about using an amp for your strongest and weakest signals, then it would possibly be overload by the strongest signals which would harm FOX by reducing its SNR from spurious signals created in the amp from IMD (intermodulation distortion). But, if you used the amp just for FOX, it wouldn't create that problem.

Thank you posting the diagram. I see that you are using a splitter in reverse to combine your 91XG and you C2V. This is not a good idea because both antennas can pick-up the same UHF channels, and when they arrive at the combiner they might interfere with each other. Sometimes it works, sometimes not.

I really don't have a lot of information about your set-up other than what you have told us, but I'll try to second-guess your installer.

My suggestion would be to use the 91XG just for FOX with an amp to bring it up to the level of your stronger channels and then feed the output of the amp into your CH 49 TinLee AC7, along with the C2V.
http://www.tinlee.com/CATV-Signal-Injector.php?active=1
http://www.tinlee.com/PDF/AC7-custom...kup%20Info.pdf

FOX probably will never be 100% reliable because it is a 2Edge signal.

But I see that you have been down this road before, and am beginning to feel like I have been sent on a Snipe Hunt, so I'm not sure I can add anything useful except to say what you have already been told:

Try each antenna alone to get what you want from it, and then figure out a way to combine them.

Maybe that's why you didn't get any answers this time.

Your previous threads:

help troubleshooting 23-Apr-2014, 7:02 PM
http://forum.tvfool.com/showthread.php?t=14436

inconsistent reception of local Fox 6-Jan-2014, 1:01 PM
http://forum.tvfool.com/showthread.php?t=14046

Need antenna help 7-Jun-2013, 5:35 PM
http://forum.tvfool.com/showthread.php?t=13368

need help in Ozark, MO 24-Jul-2012, 12:46 PM
http://forum.tvfool.com/showthread.php?t=10056

Why don't you talk to a TinLee engineer if your AC7 isn't doing what it's supposed to do?

[ADTech]

I'm trying to understand why, if they were there to help, they would take out the correct device, the AC7, and replace it with a more lossy, incorrect device, then add an el-cheapo amplifier like a Skywalker (probably a SKY38323). If they used that particular amp and a standard splitter, they probably introduced more than 10 dB of extra noise into the system on channel 49

Did they bring any test gear with them, namely a signal level meter or a spectrum analyzer, so they could actually see and measure the relevant signals before making changes to the system?

Look at the SBR reading for UHF 49 on the DVR diagnostics menu. Between that and the error numbers, corrected and uncorrected, it will give you an idea of what the tuners are experiencing.

[rabbit73]

I agree with ADTech.

mulliganman:

If you have any more questions about your antenna system, please use this thread instead of starting new one. It is hard enough as it is for us to make an analysis of your problem if it is spread out over four threads.

If you have trouble finding this thread again just click on your username mulliganman in any of your posts and click on Find More Posts by mulliganman in the dropdown menu.

[mulliganman]

Originally Posted by rabbit73

I saw your last post before you edited it.

Most of the people that help with reception problems volunteer their time. Those that are paid to do it probably want to do something else in their free time.

There were probably many people that read your thread, but couldn't think of a suggestion that would help you.

In my case, I'm the care-giver for my wife who is not well, so I come here to forget about my problems.

You probably saw my previous post in your e-mail. I deleted it because I didn't have the time then to make a good analysis of your problem.

If he was talking about using an amp for your strongest and weakest signals, then it would possibly be overload by the strongest signals which would harm FOX by reducing its SNR from spurious signals created in the amp from IMD (intermodulation distortion). But, if you used the amp just for FOX, it wouldn't create that problem.

Thank you posting the diagram. I see that you are using a splitter in reverse to combine your 91XG and you C2V. This is not a good idea because both antennas can pick-up the same UHF channels, and when they arrive at the combiner they might interfere with each other. Sometimes it works, sometimes not.

I really don't have a lot of information about your set-up other than what you have told us, but I'll try to second-guess your installer.

My suggestion would be to use the 91XG just for FOX with an amp to bring it up to the level of your stronger channels and then feed the output of the amp into your CH 49 TinLee AC7, along with the C2V.
http://www.tinlee.com/CATV-Signal-Injector.php?active=1
http://www.tinlee.com/PDF/AC7-custom...kup%20Info.pdf

FOX probably will never be 100% reliable because it is a 2Edge signal.

But I see that you have been down this road before, and am beginning to feel like I have been sent on a Snipe Hunt, so I'm not sure I can add anything useful except to say what you have already been told:

Try each antenna alone to get what you want from it, and then figure out a way to combine them.

Maybe that's why you didn't get any answers this time.

Your previous threads:

help troubleshooting 23-Apr-2014, 7:02 PM
http://forum.tvfool.com/showthread.php?t=14436

inconsistent reception of local Fox 6-Jan-2014, 1:01 PM
http://forum.tvfool.com/showthread.php?t=14046

Need antenna help 7-Jun-2013, 5:35 PM
http://forum.tvfool.com/showthread.php?t=13368

Why don't you talk to a TinLee engineer if your AC7 isn't doing what it's supposed to do?

Yes I understand about others. That's why I changed my original follow up post. I didn't want it to be misunderstood.

Regarding the reverse splitter, that was one of my concerns I wanted feedback on. I place tremendous value on the feedback given here. That's why I wanted to bring it up. I'll explain more about their thinking regarding the Tinlee combiner in response to ADTech's post.

I don't really understand the SNR. If it would be helpful to understanding and resolving this, if someone could explain I'd appreciate it.

Regarding amplification for Fox alone I have these amps on hand or on the way to me: http://www.amazon.com/Winegard-HDA-2...negard+hda-200

http://www.amazon.com/Winegard-LNA-1...inegard+lna+00

http://www.amazon.com/RCA-TVPRAMP1R-...rds=rca+preamp

I actually have 2 of the RCA.

Regarding the Snipe hunt: I am sorry you feel/felt that way. I debated considerably before started the thread. I was fearful others might feel that way. But, quite frankly I didn't know where else to turn.

[mulliganman]

Originally Posted by rabbit73

I agree with ADTech.

mulliganman:

If you have any more questions about your antenna system, please use this thread instead of starting new one. It is hard enough as it is for us to make an analysis of your problem if it is spread out over four threads.

If you have trouble finding this thread again just click on your username mulliganman in any of your posts and click on Find More Posts by mulliganman in the dropdown menu.

Yes I understand the request and have no problems with it. I thought it best to start a new one because I felt if I posted in one of the other threads it would be too difficult to follow.

[mulliganman]

Originally Posted by ADTech

I'm trying to understand why, if they were there to help, they would take out the correct device, the AC7, and replace it with a more lossy, incorrect device, then add an el-cheapo amplifier like a Skywalker (probably a SKY38323). If they used that particular amp and a standard splitter, they probably introduced more than 10 dB of extra noise into the system on channel 49

Did they bring any test gear with them, namely a signal level meter or a spectrum analyzer, so they could actually see and measure the relevant signals before making changes to the system?

Look at the SBR reading for UHF 49 on the DVR diagnostics menu. Between that and the error numbers, corrected and uncorrected, it will give you an idea of what the tuners are experiencing.

Their first job was to establish the Moca line separate from the TV signal line. But, I had also said that I was experiencing cut-outs (I don't know if they are best described as small pixelation or something else not just exclusive to any single channel). I thought maybe extra amplification might help since I had checked the signal strength percentages on my Roamio. In fact, I specifically mentioned trying the RCA TVPRAMP1R on the 91XG to see what effect that might have. Well when they began to attempt to address what I was describing they took the Tinlee combiner out of the picture feeling like it was causing part of the problem. They chose to use the Skywalker amp I guess because it was already in my attic (even though it was not in use) and felt it would fit the bill for just amplifying Fox (although I had a Winegard LNA 100 they could have used too). They had put it whatever was needed to get Cozi TV and Antenna TV broadcasting in my area so it was tough to try to argue with them....

Regarding what you asked about the Spectrum analyzer or signal level meter, they didn't have that with them. They made mention if this setup they put in (shown in the diagram) didn't work the only other thing they could try is some other antenna they have could be put up in my attic with the help of some signal tool they have.

[mulliganman]

Originally Posted by ADTech

Look at the SBR reading for UHF 49 on the DVR diagnostics menu. Between that and the error numbers, corrected and uncorrected, it will give you an idea of what the tuners are experiencing.

I went into the DVR diagnostics menu on the Roamio to get some info for all channels. Here is what it shown (as setup in the diagram I posted):

Channel 3-1 signal strength 55%, 22 dB SNR, RS Corrected 0, RS Uncorrected 66

Channel 3-2 signal strength 55%, 22dB SNR, RS Corrected 0, RS Uncorrected 60

Channel 3-3 signal strength 57%, 23 dB SNR, RS Corrected 0, RS Uncorrected 81

Channel 10-1 signal strength 67%, 27dB SNR, RS Corrected 0, RS Uncorrected 30

Channel 21-1 signal strength 52%, 21 dB SNR, RS Corrected 0, RS Uncorrected 132

Channel 21-2 signal strength 52%, 21 dB SNR, RS Corrected 0, RS Uncorrected 30

Channel 21-3 signal strength 52%, 21 dB SNR, RS Corrected 0, RS Uncorrected 60

Channel 27-1 signal strength 60%, 24 dB SNR, RS Corrected 0, RS Uncorrected 6

Channel 33-1 signal strength 60%, 24 dB SNR, RS Corrected 0, RS Uncorrected 0

Channel 33-2 signal strength 60%, 24 dB SNR, RS Corrected 0, RS Uncorrected 120

Channel 33-3 signal strength 60%, 24 dB SNR, RS Corrected 0, RS Uncorrected 45

Channel 49-1 signal strength 45%, 18 dB SNR, RS Corrected 0, RS Uncorrected 6

Channel 49-2 signal strength 45%, 18 dB SNR, RS Corrected 0, RS Uncorrected 0

[rabbit73]

antennas needed are determined by real channel:
http://www.rabbitears.info/market.ph...&callsign=krbk

3.1 virtual is real channel 44
10.1 virtual is real channel 10
21.1 virtual is real channel 23
27.1 virtual is real channel 28
33.1 virtual is real channel 19
49.1 virtual is real channel 49

Do you have the corrected and uncorrected numbers reversed?

What happens if you connect each antenna directly to your TV instead of the Roamio? Does your TV have a signal strength indicator?

[mulliganman]

Originally Posted by rabbit73

antennas needed are determined by real channel:
http://www.rabbitears.info/market.ph...&callsign=krbk

3.1 virtual is real channel 44
10.1 virtual is real channel 10
21.1 virtual is real channel 23
27.1 virtual is real channel 28
33.1 virtual is real channel 19
49.1 virtual is real channel 49

What happens if you connect each antenna directly to your TV instead of the Roamio? Does your TV have a signal strength indicator?

Regarding the corrected and uncorrected numbers that is no mistake. Ever since I have had the unit I have never seen anything other than "0" on the RS Corrected column. What I put in the post is what the Tivo Roamio menu showed me.

They did check signal strength levels on the 1 TV while they were here. Since the TV only has 1 tuner it shows very high signal strength on all channels. I think Fox was somewhere near 97%. That's how they were arriving at the conclusion that little amplification should be used. If you need exact signal strength percentages to compare to what I posted for the Roamio I can provide that for all channels. Just let me know.

[rabbit73]

Just wondering about FOX. Does it behave better when the 91XG is connected directly to the TV instead of your present setup?

[mulliganman]

Originally Posted by rabbit73

Just wondering about FOX. Does it behave better when the 91XG is connected directly to the TV instead of your present setup?

Just to be clear, you are saying how is Fox if the coax from the 91XG is just connected to the basement television (minus the Roamio)?

I haven't looked at that in a while but I assume it is probably similar or slightly better since we are only dealing with 1 tuner as opposed to 4.

If I need to connect it that way, I can. i will just need to do at a time when the spouse isn't trying to watch TV because I don't believe the Minis will get a TV signal if the Roamio isn't getting the feed directly.

[ADTech]

I'd like to take a closeup look at your precise location.

Follow the instructions in the fist three paragraphs of this post, then spot the marker on the location on your rooftop s accurately as possible where the 91XG is located. Then copy and past the coordinates that are under the lower left of the map to me in a private massage if you don't want them published in the clear to anyone. I don't need (or want) a plot, I need a very precise location so I can look at your surroundings, especially terrain and foliage in the direction of Springfield.

Swap out the Skywalker for the LNA100 up in the attic. It's got the best noise figure and overload characteristics of any of the amps you have on hand, but it mus be indoors only unless you make an outdoor enclosure for it and provide power. If your coax from the 91XG to the attic amp is more than 25l long, then it would be better to use the RCA as the amp with a very short (3') lad between it and the antenna.

On channel 49, your SNR is only 18 while digital reception, requires 15-16. It's teetering right on the edge of the "digital cliff" and it doesn't take much natural signal variation to push it over the edge into failure. Swapping the LNA100 for the Skywalker *should* improve SNR by 6+ dB and putting the AC7 back in in place of the splitter should pick up another 2-3 or so.

My suggested sequence of connections if using the RCA would be: 91XG > AMP (set to SEPARATE) UHF input > downlead >power inserter>AC7 ch 49 INPUT. The other input of the AC7 would get the C2V signal.

My suggested sequence of connections if using the LNA100 would be: 91XG > downlead (as short as possible) > LNA100>AC7 ch 49 INPUT. The other input of the AC7 would get the C2V signal.

I can tell you from practical experience that not every reception issue can be satisfactorily resolved. Often, one hits the limit of what can be reasonably or willingly done and it's finally time to accept the results. My own home's location (back side of a tree-covered hill) causes the summertime loss of reliable reception of several of the UHF channels from the antenna, but I've just learned to accept that they will be back come November. It does feel better when you stop beating your head against the wall, you know...