# Discussion of Bug: 811 OTA reception (Is there more 49% lock issue since P284)



## jla376 (Oct 14, 2004)

I am getting only a 49% signal(it will jump to 60% for a moment occasionally) on one of my local digital channels. I have tried (several times) clearing my favorites and unplugging the receiver, only to continue having the problem.

Local station info:
NBC 27.1 to 5.1
Bristol, VA
signal mid to upper 80's

ABC 28.1 to 19.1
Kingsport, TN
signal upper 70's

CBS 58.1 to 11.1
Johnson City, TN
www.tricities.com
signal 49%

My receiver is showing software version 284(problem seemed to start with this download)

All three transmitters atop same mountain, I don't even have to move my antenna.

Any suggestions appreciated.


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## moman19 (Oct 22, 2004)

jla376 said:


> I am getting only a 49% signal(it will jump to 60% for a moment occasionally) on one of my local digital channels. I have tried (several times) clearing my favorites and unplugging the receiver, only to continue having the problem.
> 
> Local station info:
> NBC 27.1 to 5.1
> ...


I saw this once. Try all you did again. Delete your OTA's first. Then the favorites. Unplug the 811 and wait a full minute. Start from scratch. Good luck. It worked for me & has been working fine ever since.


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## Jason Nipp (Jun 10, 2004)

Have you tried adjusting your antenna?, Seriously? Indoor, Outdoor? 

Here's a tip courtesy of Tom. Is your antenna 75 ohm matched. Tom was having a multipath issue and pretty much fixed it by cutting the 300 ohm leads off and putting a 75 ohm matching transformer right at the antenna.

But I'd try Moman's suggestion of dumping your map and pulling the plug first.


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## Ron Barry (Dec 10, 2002)

I would also suggest contacting the station to make sure they did not lower power or possible make some PSIP changes recently. My general plan of action is to rule out external factors first if possible before trying to debug your system. You might find that you system is fine, but the station lowered its power.


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## jla376 (Oct 14, 2004)

Jason Nipp said:


> Have you tried adjusting your antenna?, Seriously? Indoor, Outdoor?
> 
> Here's a tip courtesy of Tom. Is your antenna 75 ohm matched. Tom was having a multipath issue and pretty much fixed it by cutting the 300 ohm leads off and putting a 75 ohm matching transformer right at the antenna.
> 
> But I'd try Moman's suggestion of dumping your map and pulling the plug first.


I am using an outside top of the line Radio Shack antenna with a 75 ohm connection to a Winegard amp, with a Channel Master rotator and approx. 40 ft above ground level. All towers are approx. 9 miles from me, as the crow flies, and are situated side by side (within a couple degress lat/lon) on the mountain top.

I will try the dump and unplug again tonight.


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## rocatman (Nov 28, 2003)

jla376 said:


> I am using an outside top of the line Radio Shack antenna with a 75 ohm connection to a Winegard amp, with a Channel Master rotator and approx. 40 ft above ground level. All towers are approx. 9 miles from me, as the crow flies, and are situated side by side (within a couple degress lat/lon) on the mountain top.
> 
> I will try the dump and unplug again tonight.


Sounds like a multipath issue. Unless the station you are having problems with is transmitting at a very low power, you should be able to get all your stations with an indoor antenna from 9 miles away. I used to have a similar setup to yours with a top of the line Radio Shack antenna and amp with towers about 20 miles away. I tried taking the amp out, and that helped but then I tried an amplified indoor antenna in my attic garage. There was a great improvement and I really have not had a problem with my locals since.


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## Ron Barry (Dec 10, 2002)

gsel said:


> I certainly sounds like you have a plenty strong signal. Do you have a very long run to your receiver from the antenna (more than 100 feet), or are you splitting the signal to several TVs (more than two)? If neither of these is the case, try it without any amplification. This could increase the multipath as well as the signal to a point where the receiver cannot deal with it.


qsel makes a good point. If you are only 9 miles away you should not need an amp in most cases. Especially with a single receiver hooked up. Are you running this through a power conditionar or surge protector? At 9 miles, I would take out any external devices from the loop.. I would also look into a possibility of a antenna that is more directional in nature if your RS one is not of that type.

But ofcourse, first step is to do the task that does not require any external modifications. The one moman suggested.


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## Jason Nipp (Jun 10, 2004)

There is an exception to this rule WJD and GSEL. It is a phenomenon known as the umbrella effect. You see transmitters are designed to transmit it's signal a certain wavelength or distance for that matter. As such you could be getting an umbrella effect were as you are actually too close to the tower and it broadcasts the cleanest undistorted signals right over your head. Ya I know it sounds like B.S. But anyone that studied RF or microwave communications knows that there is many factors that could impact transmission: like the atmospheric propagations of Tropospheric Scatter, Ionospheric Propagation, F2 Propagation, or Trans-equatorial Skip, Aircraft Scatter, Aurora and Sea path ducting, etc. The list goes on and on. Multipathing, weak signal, bad PSIP data, clip on antennas with a gazillon diplexors, 300 ohm antennas in your basements, etc.  

Of course it's always easiest to blame the receiving equipment. After all it doesn't look like there is anything else in an OTA setup that could contribute. :sure:


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## Ron Barry (Dec 10, 2002)

Jason Nipp said:


> There is an exception to this rule WJD and GSEL. It is a phenomenon known as the umbrella effect. You see transmitters are designed to transmit it's signal a certain wavelength or distance for that matter. As such you could be getting an umbrella effect were as you are actually too close to the tower and it broadcasts the cleanest undistorted signals right over your head. Ya I know it sounds like B.S. But anyone that studied RF or microwave communications knows that there is many factors that could impact transmission: like the atmospheric propagations of Tropospheric Scatter, Ionospheric Propagation, F2 Propagation, or Trans-equatorial Skip, Aircraft Scatter, Aurora and Sea path ducting, etc. The list goes on and on. Multipathing, weak signal, bad PSIP data, clip on antennas with a gazillon diplexors, 300 ohm antennas in your basements, etc.
> 
> Of course it's always easiest to blame the receiving equipment. After all it doesn't look like there is anything else in an OTA setup that could contribute. :sure:


That is why you Rock Jason. I thought about being too close as a possibility since I have heard some reports of this scenario. However, I could not put it down in the same way you could. I am a software guy not a hardware guy.  This is why OTA is an art and not a science to some extent. Tricky stuff!


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## Jason Nipp (Jun 10, 2004)

gsel, your explanations and tone very much remind me of somebody I know. 

Don't get me wrong, I am not challenging you. I think alot of bases have been covered by this thread and I am venturing a guess somebody learned from it. 

Good stuff keep up the good posts.


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## moman19 (Oct 22, 2004)

WOW! You guys have over-analyzed this issue to DEATH! At 9 miles out, the guy should get good reception with a bobby pin. He said he has the top-of-the-line antenna 40 feet in the air. That's great when you live 100 miles away from civilization. But unless it's pointed 108 degrees in the wrong direction (i'll bet it would still work!) he should be getting signal in the upper 90s.

I'll bet the it's one of two things: Either the 60-second unplug, start-from-scratch will resolve this or; he's simply overloading the RF inputs with such a huge antenna so close to the towers. If the latter, a simple attenuator at the input might just do the trick.

Then again, it could be sun spots


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## Jason Nipp (Jun 10, 2004)

moman19 said:


> he should be getting signal in the upper 90s.
> 
> I'll bet the it's one of two things: Either the 60-second unplug, start-from-scratch will resolve this or; he's simply overloading the RF inputs with such a huge antenna so close to the towers. If the latter, a simple attenuator at the input might just do the trick.


Where's it say he has a top of the line antenna? Rad Shack? Just because an antenna is a retail stores top of the line doesn't mean it's the best for the application. This is why it is important to go up to antennaweb.org or checkhd.com and spec out a proper antenna for your application and geographic. If the transmitter is on a mountain top and he at the base of the mountain that even introduces more variables. There's many guys in here that will take your challenge on that one. :grin:

As far as Signal strength on the 811, you must remember the bar and percentage is not merely signal strength alone. I have learned that on the 811, the reading for signal strength when you are tuning to the DTV channel is more like a combination of strength and quality rather than just strength. When it shows 49%, it is typically getting a strong enough but distorted signal. If the distortion can be resolved by the tuner, it will be seen as changing around often from 49% to 0% and then maybe finally lock in at something like 80%. This is the receiver trying to get all the phase noise or multipath out of the signal digitally to make up for the problem in the feed.


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## Ramasis (Mar 6, 2005)

I Get a lot of these calls per day. What we also suggest is either a TERK antenna, or Rooftop antenna. I have seen the bowtie ( indoor) TERK antenna work to pick up the Digital locals in my area. Have heard from techs in the field that 49 is a good signal.


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## Ron Barry (Dec 10, 2002)

Ramasis said:


> I Get a lot of these calls per day. What we also suggest is either a TERK antenna, or Rooftop antenna. I have seen the bowtie ( indoor) TERK antenna work to pick up the Digital locals in my area. Have heard from techs in the field that 49 is a good signal.


To get Reliable OTA on an 811, you need to have a signal around 70% from what I can tell. 49 is not going to do it in 811 terms.


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## Jason Nipp (Jun 10, 2004)

Ramasis said:


> I Get a lot of these calls per day. What we also suggest is either a TERK antenna, or Rooftop antenna. I have seen the bowtie ( indoor) TERK antenna work to pick up the Digital locals in my area. Have heard from techs in the field that 49 is a good signal.


At 49 an 811 will not lock onto a Digital OTA Signal.


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## jla376 (Oct 14, 2004)

Well the clear and unplug made no difference. I tried it five times.

To answer a couple of your questions:

Cable(rg-6 quad shield) run less than 75' to 811 only.

Awaiting email response from station engineer concerning power and psip.

As I stated before I received all three stations prior to download of 284 update.

I will try bypassing amp as soon as the weather permits(very windy).


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## the_bear (Oct 18, 2004)

I too think multi-path rejection was made worse with P284. If you leave the no signal screen up for 15 minutes does the 811 eventually lock? This was the case me.


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## Cokeswigga (Jan 25, 2005)

the_bear said:


> I too think multi-path rejection was made worse with P284. If you leave the no signal screen up for 15 minutes does the 811 eventually lock? This was the case me.


Yes I have the same issue with KABC-DT (ch 53) from Los Angeles. I live about 70 miles southeast of L.A.

KABC-DT is the only channel which does not immediatly lock in. The error message comes up, and then if I wait for about 15-30 *seconds* and then it will tune in, with a good signal strength of about 80+ (but this only happens about 75% of the time the other 25% I have to either not watch this channel or keep trying to tune it in sometimes after a few minutes it will tune in too).

*Question* Does multipathing effect a broad range of frequencies or usually just one?
Would ganging another antenna, help with multipath rejection or make it worse?

I have no problem tuning in any other channels.


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## Ron Barry (Dec 10, 2002)

I am also in SoCal. Like I mentioned earlier. Not sure if 2.84 is more problematic with locking. I am getting KABC-DT. KABC-DT has been one of the more problematic stations for me even before 2.84. 

I did notice some unusual about a week ago. KABC started to not lock on. I would get a blank screen. However when I would bring up the EPG a second time it would immediately lock. The process was Press EPG and select KABC, get a blank screen, the blank screen would sit there for what seem like a minut or so, I would then press the EPG again and the picture would appear in the EPG PIP. I then would select KABC again and everything was cool.

THis was occuring for about a day. I thought my 811 was having an issue so I did not reboot. Well after about a day it cleared up. This makes me feel it was something on the deliver side. 

Cokes, Try my procedure and see if you get the same results as I did. Maybe there is some funky state the 811 gets into. In my case it eventually got out. 

I assume that your condition is happening all the time? like I said, Mine only happen once and it lasted for a day and cleared up without a reboot. I assumed it was on the delivery side.


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## Broadband Lab Rat (Nov 4, 2003)

My 811 w/2.84 still has serious 49% issues, but no more than it did with the other releases.

I have one weak station (FOX) that is always the culprit. It starts the 49% problem every 3 to 4 weeks, but I flush my favorites and scanned channels, power cycle, and rescan... it always recovers with 65-75% on the same station that was 49% beforehand.

My HTPC using a MyHD MDP-130 card never has any issues receiving the same station. My old Samsung OTA receiver always works as well... 

I doubt the problem will ever be solved with the 811, as it''s surely been attempted many times...


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## Cokeswigga (Jan 25, 2005)

Ron Barry said:


> Cokes, Try my procedure and see if you get the same results as I did. Maybe there is some funky state the 811 gets into. In my case it eventually got out.
> 
> I assume that your condition is happening all the time? like I said, Mine only happen once and it lasted for a day and cleared up without a reboot. I assumed it was on the delivery side.


Well I tried your method, and I get a black picture in the little picture box when the EPG is up.

I think my receiever just has a hard time tuning in KABC. It usually tunes it in with in about 40 seconds. But all my other channels tune in right away.

Some people have suggested that i am experiencing multipath.

would stacking another antenna make this problem better or worse?


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## Ron Barry (Dec 10, 2002)

I am not sure if stacking an antenna would help.. It does sound like a multipathing issue and I would expect techniques to limit multipathing would help. Not sure what those are though.. I am a software guy.  Have you checked out AVSForums and see what people are doing in your area? 

For what it is worth. I am using a channel master 3022/4308 Magnadyne and channel master 7778 Preamp. Not sure what type of antenna you have, but going to something more directional based also might help.


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## misterdsp (Apr 22, 2004)

I didn't notice any difference in locking ability with 2.84.

Most of my channels are in the low 80's or mid 70's. I have one channel that hovers around 72%, but will drop to 60 for a blink and then pop back up. That's pretty annoying, because the picture will break up and the sound will screw up.

The exact same signal into my FusionHDTV PCI card locks with no problems, no dropouts. My best estimate is that the 811 is about 2dB less sensitive than the FusionHDTV, and the 811 isn't as resistant to whatever is causing it to dropout (maybe multipath, but I can't say for sure). At this phase of the 811 development (i.e. it's been available for more than 12 months) I have to believe the OTA reception is as good as it's going to get and not to expect any improvements.

According to antennaweb, I am in a blue and violet antenna zone. I use a ChannelMaster 3020 with a 25dB preamp.


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## Cokeswigga (Jan 25, 2005)

Ron Barry said:


> I am not sure if stacking an antenna would help.. It does sound like a multipathing issue and I would expect techniques to limit multipathing would help. Not sure what those are though.. I am a software guy.  Have you checked out AVSForums and see what people are doing in your area?
> 
> For what it is worth. I am using a channel master 3022/4308 Magnadyne and channel master 7778 Preamp. Not sure what type of antenna you have, but going to something more directional based also might help.


It's a winegard hd9095p with a AP-4700 preamp.


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## the_bear (Oct 18, 2004)

I pulled my antenna amp out. This did not make a difference on the 811 signal quality meter, and resulted in a little faster locks. This tells me the signal loss in the coax is negligible. I was probably amplifying the unwanted signals as well. Since I never had great reception, the really slow locks gave me the needed incentive to upgrade my antenna, now 13 feet long, which also helped considerably. This seemed easier than stacking. I also considered using an attenuator, but since my signal is already pretty weak (62-74 varies with weather), I do not think it would help.

I do not have line-of-sight to the transmitting antennas, so I point mine to a nearby valley. This results in severe multi-path. There is an analog station on the same transmitting antenna at a nearby frequency which shows multiple very pronounced ghost images. I am somewhat amazed that I can lock anything. The antenna crew from a local station came by my house and was also amazed I could lock at all. With that being said, I have seen posts that other tuners are even better at handling multi-path than the 811, which really makes me wonder what the 942 will be like, since I still get occasional dropouts.


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## Ron Barry (Dec 10, 2002)

I have heard the 942 does have a better OTA tuner than the 811. I can't verify it, but I have heard it mentioned in one or two places.


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## waltinvt (Feb 9, 2004)

Jason Nipp said:


> <snip>......As far as Signal strength on the 811, you must remember the bar and percentage is not merely signal strength alone. I have learned that on the 811, the reading for signal strength when you are tuning to the DTV channel is more like a combination of strength and quality rather than just strength. When it shows 49%, it is typically getting a strong enough but distorted signal. If the distortion can be resolved by the tuner, it will be seen as changing around often from 49% to 0% and then maybe finally lock in at something like 80%. This is the receiver trying to get all the phase noise or multipath out of the signal digitally to make up for the problem in the feed.


I have a similar 811 / 49% question.

I'm at about 680 feet with a rooftop antenna: (getting these off the installer's invoice) a CWI9022 UHF (Yagi type) antenna, 9521A rotor and AP8275 Amp.

I get one digital PBS station that's 40 miles away that locks in well with mid 80s signal.

I also am getting signal activity from 3 or 4 other stations that range from 70 to 120 miles away. If I get the antenna rotated just right, I can get the meter to stay solid at 49% with occasional split second peaks of 56 to 63%.

Is there much chance of ever locking these stations ?

Right now my antenna is mounted on the side of a dormer and extends up about 2 feet above a metal roof. Also the metal roof is between the antenna and the signal source so I'm wondering if it could be interfearing.

Looking at the system, I don't see that the antenna could be raised more that a few inchs without changing the mast length or how it's mounted. I probably could relocate it to the other side of the house so it wouldn't have to "look" over the roof when pointed at those stations. The only other option would be going on the roof itself with a longer mast and guide wires.

I guess I'd like to know if I stand much chance before I attempt either.

Thanks,
Walt


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## the_bear (Oct 18, 2004)

waltinvt said:


> I also am getting signal activity from 3 or 4 other stations that range from 70 to 120 miles away. If I get the antenna rotated just right, I can get the meter to stay solid at 49% with occasional split second peaks of 56 to 63%.


70 miles is a pretty long distance for UHF. Your problem is probably distance, rather than multi-path. I think you would need a much bigger/higher antenna to get these. You can find more info at:

http://www.avsforum.com/avs-vb/forumdisplay.php?s=&forumid=45


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## Cokeswigga (Jan 25, 2005)

I discovered something interesting today.

I am supposed to get KABC (which is at 297 degrees about 70 miles away
Problem is that it takes about 30 seconds to lock in if it locks in at all. (usally about 75% of the time it does lock in eventually, it just takes some time. Once it locks, it comes in at 80+

Now today.. I was trying to tune in san diego stations at 180 degrees.. (which points right to a mountain a few miles away)and guess what channel popped in during the scan... KABC with a signal strength of 61. Guess what, it immediatly locked in, with no problems.

So is this to lead me to believe that my locking problem is due to multipath at 180 degrees?

My question is, why is the weaker signal (from 180, i guess bouncing off the mountain) tune in *without* a problem, and the stronger signal (from 297) *has a problem * tuning in.


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## Grandude (Oct 21, 2004)

My guess is that there is more than one multipath signal from KABC when pointing at 297 degrees and when you pointed at 180 degrees the main signal from 297 was at a null point in the antennas reception pattern. Some antennas pick up pretty good off the back. What antenna are you using?


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## Cokeswigga (Jan 25, 2005)

I am using a winegard 9095

I noticed that the winegard 9032 has a much higher front to back ratio, 

but the antenna itself does not look as high of a build quality as the 9095, and it's inexpensive ($35) vs the 9095 at $70+


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## jla376 (Oct 14, 2004)

Just thought I would let you guys know I have solved the problem. 

I took down the large multdirectional antenna and replaced it with a 4-bowtie unit that I have had in storage for last 2 or 3 years. Now I am receiving all 3 local networks(in hd).

I appreciate everyone's help and suggestions. The people are what makes DBSTalk valuable.


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## the_bear (Oct 18, 2004)

When I was buying some batteries at Radio Shack yesterday, the salesman said they got a new ASTC tuner. I asked how the muli-path capabilities were. He said, “Why don’t you try it out?” So I did. Not a single station would lock. Its back to the 811.


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