TVs with best reception OTA - Page 2 - Canadian TV, Computing and Home Theatre Forums

Reply
 
LinkBack Thread Tools Search this Thread Display Modes

post #16 of 41 (permalink) Old 2017-09-20, 03:25 PM
Veteran
 
Join Date: Jun 2011
Location: 43░ N, 81.2░ W
Posts: 5,787
@Billiam62 , It sounds like the best place for your antenna is on the neighbor's roof. LOL

But realistically, 17' is kind of low for an antenna, especially if there are houses and trees within sight. Raising it another 5' or 10' may make all the channels available. Plugging different heights into TVFool until they all become 1 edge will give a good height to aim for. LOS would be ideal but is not always easily obtained.
ExDilbert is offline  
Sponsored Links
Advertisement
 
post #17 of 41 (permalink) Old 2017-09-20, 07:39 PM
 
Join Date: Jul 2016
Posts: 43
Mapmaker. I will give that a look. I have not tried the Satellite feature yet.

Since I just moved my antenna mast back to the original position 10 feet to the west, it will require some relearning where getting the three weakest signals is concerned. I am going to put in a cement base and raise the mast to at least 21 feet to get the UHF antenna over the apex of the roof. I think that along with using a 4 or 8 bay again will eliminate the picture breakup. I noted during thunderstorms that both my U4000 and Super G 1483 8 bay would hold a steady picture without breakup while the MXU 47, MXU 59, HBU 22 and new Televes DAT 790 Mix would or will have picture break up at times.
Billiam62 is offline  
post #18 of 41 (permalink) Old 2017-09-21, 12:01 AM
Veteran
 
Join Date: Jan 2009
Posts: 4,258
based on the fact you are using a preamp, as you posted in this other thread, and are only 3.4 miles from transmitters per your tvfool, the symptoms you describe are implying you are having intermod distortion problems, not multipath problems.

correct me if I am wrong here is your tvfool:
4 bay antenna question

Lowering the height, adds more pathloss between your antenna and the transmitters,
ie obstructions like your neighbors houses, etc. reduces the strength overall of signals entering your preamp, which in turn gets it out of intermod trouble, which in turn reduces the noise floor, which results in better reception overall. As described by holl_ands numerous times, if your preamp is in intermod territory, for every 1 dB of reduced input signal, reduces the output noise floor by 3 dB.

Try the same test without the preamp at all, and I suspect you will have much different results. You might have better luck keeping the noise floor under control, using an antenna with only modest gain. Say a GH without any reflectors or even 'stealth hawk'.

I would really suggest getting a PC based tuner that can indicate both Signal Strength, in dBm and SNR in dB, so you will have a better understanding of what is going on.
Many devices like the hauppauge 950q, or the hdhomerun are not that good at accurately displaying the 'strength' of signals to the user, because they "Top Out" too early to be useful for troubleshooting like this. My favorite device for such tests is the newer hauppauge 955Q.
Which seems to have a wide range of SNR indication, and also provides an indication of Strength in dBm.
At least when used in linux it does. I can't speak for windows, since I don't use windows.

DB4E/VHF Yagi rotor FM Bandstop ap-8700 preamp 4way split LG lcd.
majortom is online now  
 
post #19 of 41 (permalink) Old 2017-09-21, 09:53 AM
Veteran
 
Join Date: Jun 2011
Location: 43░ N, 81.2░ W
Posts: 5,787
Nice catch majortom. The number of strong signals and their very high levels definitely indicate an issue when using a preamp. Any preamp in use would need to be extremely resistant to overload and quite moderate in gain in order to prevent tuner overload. It could also explain why the antenna works better when it is aimed at the neighbor's roof as that might reduce the level of all signals, reducing overload issues. Using a preamp in this scenario, I would expect to see IM distortion causing harmonic signals across the UHF band due to preamp or tuner overload. That would interfere with weaker signals.
ExDilbert is offline  
post #20 of 41 (permalink) Old 2017-09-21, 11:12 AM
DHC Supporter
 
Join Date: May 2010
Location: S.E. VA
Posts: 687
Quote:
Originally Posted by majortom View Post
based on the fact you are using a preamp, as you posted in this other thread, and are only 3.4 miles from transmitters per your tvfool, the symptoms you describe are implying you are having intermod distortion problems, not multipath problems.

correct me if I am wrong here is your tvfool:
4 bay antenna question
Quote:
Originally Posted by ExDilbert View Post
Nice catch majortom. The number of strong signals and their very high levels definitely indicate an issue when using a preamp. Any preamp in use would need to be extremely resistant to overload and quite moderate in gain in order to prevent tuner overload.
Well, including holl_ands, that's four of us that think overload when we see his report.

I'm not able to be at his location to make signal measurements, but after seeing a satellite view of his area and reading his posts on another forum, I'm willing to give him the benefit of a doubt.

It would be helpful if Billiam62 could show us some photos of the trees around his house in the north direction.



Using his former username, Billiam gave more background information about his location. The rules of this forum don't allow me to link to another forum, but here are a few quotes that indicated trees are a problem:
Quote:
Originally Posted by Billiam
Potentially another flag on the play.
This morning before a very severe thunderstorm moved into the area I reinstalled the Antennacraft U4000 with the Titan pre amp. I did note that all my channels returned.
However, during the storm I lost several channels including local which I presume was due to the heavy rain and wind. I've never see this happen before except with really weak signals when I was living in a rural area.
This is by far the most perplexing situation I've had for receiving TV signals.
Quote:
Originally Posted by Billiam
The DAT 790 gave me stronger gain than the U4000 but a little less than my Super G 1483. I don't want to use either antenna at this location since there are trees and limbs nearby that could easily damage the antenna. Want something currently in production that can easily be replaced with the identical antenna should it meet an untimely demise due to weather.
Quote:
Originally Posted by Billiam
Rabbit. Yes, trees and buildings are a major issue at this spot. Thus I need a pre amp even for the local channels. Hard to believe but it really does help.
Quote:
Originally Posted by Billiam
I think the leaves on the trees are starting to impact the weaker signals on the TV Fool report. Have noted a bit of a drop in SS tonight though 2, 7 and 22 are still viewable. If this becomes a daily occurrence I will probably buy a larger Yagi or 8 Bay in lieu of the 4 bay.
Quote:
Originally Posted by Billiam
Joe. Thankfully I have not had to worry about overload when using a pre amp at this location. Despite the fact I am very close to some very strong signals, I seem to be in a pit that repels signals which results in none of my local channels getting pegged on the SS meter without a pre amp even when using a Deep Fringe antenna like the Super G 1483 or MXU59.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2017-09-21 at 11:29 AM.
rabbit73 is offline  
post #21 of 41 (permalink) Old 2017-09-21, 06:55 PM
Veteran
 
Join Date: Jan 2009
Posts: 4,258
I can't be there either, but if that is indeed his 'hood, I see no more trees there than any other typical neighborhood, including mine. The trees may actually help. Just like we assume his neighbor's houses are helping.

If it were me I would get a new PC based tuner, so I could see what is going on in terms of strength vs SNR on the various channels. If I wanted to reduce the input signal and keep some semblance of LOS paths, I would add some attenuation between the antenna and preamp, 2 Way splitter, with one port terminated to 75 ohms, plus an extremely long length of RG-6 coax coiled up might be enough to help keep the noise floor under control on the preamp output and is another simple test to try. But without any way to measure what is going on before and after, still kinda guessing.

Seems to work for me here, allowing me to aim straight at Grand Island, and still be able to receive a few of the stronger of stations from the distant CN tower, which is some 60 miles or so right in line behind Grand Island Transmitters. Could never do that before adding the extra attenuation, which for me was only about a 6 dB reduction in signal strength across the board. Previously would have to do that by aiming away from Grand Island. Like putting the welders goggles on to watch that solar eclipse...
But as holl_ands would say could result in up to 18 dB reduction in Noise (IMD to be specific).

DB4E/VHF Yagi rotor FM Bandstop ap-8700 preamp 4way split LG lcd.
majortom is online now  
post #22 of 41 (permalink) Old 2017-09-21, 08:07 PM
 
Join Date: Jul 2016
Posts: 43
On Sunday if I have time I will go ahead and take down the DAT 790 Mix and reinstall the U4000 and also try the Super G 1483. In both cases I didn't see any picture break up like I've had with the DAT 790 Mix even when using the pre amp. The built in pre amp of the DAT 790 may be part of the problem.

This is a bizarre location for TV and radio reception. When I used the mast that was 10 feet further to the east I was able to pick up Ch. 2, 7, 22 and 26 (virtual channels) when the antennas were pointed at 15 degrees. But in the case of the Yagi's I've tried I had to put the antenna at 17 feet at that compass heading to get Ch. 2. Raising it another couple of feet would yield Ch. 7 but I would lose Ch. 2. Ch. 26 comes in better with more height at that spot. Ch. 22 comes in fine regardless of the height. But when pointing the antenna to 100 degrees at my neighbors house I can get Ch. 2, 7 and 22 but not 26. But now with the DAT 790 mix on the mast 10 feet further to the west I don't receive any of the Dayton signals unless I have it pointed to the house at 100 degrees. Still get 2, 7 and 22 but not 26. Writing off 26 now since it will be going bye bye in the Repack. Just need 2, 7 and 22.

Me thinks that the problem will be solved by using the 4 or 8 bay again and pointed at the house. Will try different heights to see what works best.. I can probably get a maximum height of 21 to 22 feet which will get the antenna above the roof line to the NW where Ch. 5 (virtual ch.) is located which is one of the signals that breaks up even when it is pointed at the compass heading in that direction. Don't recall it off the top of my head but I think 346 degrees is about right. The TV Fool report that was mentioned is accurate. Very likely the trees are the problem since they are all over the place. Tall building nearby also contribute to the problem. It is so bad at this spot that I can't even pick up ANY DX! Ugh.

My Samsung TV has a SS readout of the SNR. I use a Mac but don't have a tuner for it. Not sure I would use it even if I had it.

Last edited by Billiam62; 2017-09-21 at 08:28 PM.
Billiam62 is offline  
post #23 of 41 (permalink) Old 2017-09-21, 08:22 PM
Veteran
 
Join Date: Jan 2009
Posts: 4,258
SNR alone doesn't tell the full story. What you need is a tuner that displays a wide range of both SNR and Strength, especially without maxing out in strength. That is where most if not all other consumer devices fail and can mislead.

DB4E/VHF Yagi rotor FM Bandstop ap-8700 preamp 4way split LG lcd.
majortom is online now  
post #24 of 41 (permalink) Old 2017-09-21, 08:27 PM
 
Join Date: Jul 2016
Posts: 43
Yes, I think I know what you mean. I recall my old 2010 Sony had both features. But that is the only TV I've owned that did. All the others like the Insignia and LG had only the SS meter and not the SNR readout.

Do you know of any new TV's that have both? I would rather not buy a stick for a computer which likely would not get used at any time other than the initial use to troubleshoot. And I don't want to buy something, use it once and return it under false pretenses.
Billiam62 is offline  
post #25 of 41 (permalink) Old 2017-09-21, 08:33 PM
Veteran
 
Join Date: Jan 2009
Posts: 4,258
sorry I do not...
Obviously it is not as practical to buy and test multiple TVs, as it is to buy and test numerous PC based tuners.
To demonstrate, below is from the hdhomerun that I have, while aimed straight at the Grand Island Transmitter site which as I mentioned above has a couple flame thrower high power TV transmitters.

If you went by the Strength column, your screwed, because it maxes out at 100 % way too early. That is what the user normally sees if they use the stock hdhomerun application provided.... If you look at the Calc_dBm column (last column on the right), that is my empirically determined real signal strength that we incorporated in to forum member 905Shmick's bash script. And that just happens to correlate fairly well with the dBm value as reported by my 955q, which can report dBm as it sees it straight away. So IMO, it's good enough to get an idea what's really going on. 14, 32, and 43 are the high power stations on GI, while 19, 20, 25 and 41 are distant stations on the CN tower some 70 miles from here that would be impossible to lock if one were to aim straight at the CN tower, which is in line with the much closer high power GI stations.
Remove that extra 6dB attenuation across the board all them signals will increase by 6 dB in strength, which in turn would drive the preamp in to
producing IMD. Remember this is at the bottom of the downlead, after amplification. So you can imagine/back your way in to what the preamp is seeing on the input. If the reduction in attenuation doesn't result in an across the board 1 for 1 increase in strength, the preamp is in compression, causing distortion. Same as if you cranked the volume up on your stereo until it becomes distorted.

The misleading part is that if all your strong signals indicate 100% on whatever device you have, what is that... 100% of what?
You have no clue whatsoever how strong they REALLY are. And that is why I say nearly all consumer devices fail in this regard.

Code:
14 channels found
RF    Strngth    dBmV    dBm    Quality    SNR    Symbol    dbg    Calc_dBmV    Calc_dBm
--------------------------------------------------------------------------------------------
14    100    0.0    -48.8    90    29.7    100    -234    26.0        -22.7
15    100    0.0    -48.8    60    19.8    100    -405    2.1        -46.6
17    100    0.0    -48.8    93    30.7    100    -276    20.2        -28.6
19    71    -17.4    -66.2    65    21.4    100    -550    -18.2        -67.0
20    74    -15.6    -64.3    69    22.8    100    -534    -16.0        -64.7
25    80    -12.0    -60.8    77    25.4    100    -499    -11.1        -59.8
26    89    -6.6    -55.4    60    19.8    100    -456    -5.0        -53.8
29    100    0.0    -48.8    96    31.7    100    -280    19.6        -29.1
32    100    0.0    -48.8    88    29.0    100    -201    30.7        -18.1
33    100    0.0    -48.8    67    22.1    100    -321    13.9        -34.9
39    100    0.0    -48.8    59    19.5    100    -340    11.2        -37.5
41    64    -21.6    -70.3    64    21.1    100    -579    -22.3        -71.0
43    100    0.0    -48.8    96    31.7    100    -280    19.6        -29.1
49    76    -14.4    -63.1    56    18.5    100    -527    -15.0        -63.7

DB4E/VHF Yagi rotor FM Bandstop ap-8700 preamp 4way split LG lcd.
majortom is online now  
post #26 of 41 (permalink) Old 2017-09-21, 09:00 PM
Veteran
 
Join Date: Jun 2011
Location: 43░ N, 81.2░ W
Posts: 5,787
Quote:
This is a bizarre location for TV and radio reception.
Two edge signals tend to be pretty bizarre most of the time. They are often a mix of refracted and reflected signals plus they are weak enough to be totally overridden by tropo, either from their own signal or from other, more distant signals. Throw in some local IM distortion from strong local signals and it's a wonder they come in at all. At least you don't have a lot of strong local adjacent channels like we have here.
ExDilbert is offline  
post #27 of 41 (permalink) Old 2017-09-21, 11:03 PM
 
Join Date: Jul 2016
Posts: 43
I also have my Insignia TV hooked up to the second output on the pre amp from the DAT 790. That TV has a SS meter. Would running that simultaneously with the SS Meter showing for a given channel at the same time I am using the Samsung's SNR readout help at all? The SS Meter on the Insignia is not all that great. Seems to read out by quarters out of 100. Zero, 25%, 50%, 75% and 100%. Never seems to read any percentage in between.
Billiam62 is offline  
post #28 of 41 (permalink) Old 2017-09-22, 10:09 PM
DHC Supporter
 
Join Date: May 2010
Location: S.E. VA
Posts: 687
Quote:
Originally Posted by Billiam62 View Post
I recall my old 2010 Sony had both features. But that is the only TV I've owned that did. All the others like the Insignia and LG had only the SS meter and not the SNR readout.

Do you know of any new TV's that have both? I would rather not buy a stick for a computer which likely would not get used at any time other than the initial use to troubleshoot. And I don't want to buy something, use it once and return it under false pretenses.
I like the Diagnostic screen on the Sony TVs that I have had: two 22", two 32", and one 40". They all have relative signal strength, SNR, and uncorrected errors. Unfortunately, the signal strength scale is different on each model. This is because a design team for a model is given the freedom to design it as they think best. This approach encourages innovation, but is more costly, and it contributed to the financial troubles for Sony.

Now, the bean counters are in charge. The designs are less expensive, but there is less innovation that made Sony famous.

Since I have a signal level meter calibrated in dBmV, I have been able to compare the sensitivity of my Sony tuners by using a splitter, and a variable attenuator in real time. Disconnecting the antenna from one tuner and connecting it to another doesn't work well, because OTA signals are constantly changing in strength. This has also allowed me to calibrate the TV signal strength scale.

My first Sony was a KDL22L5000.

Bad signal with picture freeze, SNR below 15 dB, and uncorrected errors:



Good signal:



Calibration curve:



Note that the calibration curve will MAX out at 0 dBmV, which is about what the cable companies aim for at the wall plate. The tuner is capable of handling signals up to +41 dBmV (-8 dBm) without damage. If you are making improvements to your antenna system, you will not see them if you are already at MAX, and will need to add an attenuator to measure the improvement.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2017-09-22 at 11:34 PM.
rabbit73 is offline  
post #29 of 41 (permalink) Old 2017-09-22, 10:46 PM
DHC Supporter
 
Join Date: May 2010
Location: S.E. VA
Posts: 687
My favorite Sony for antenna work is the KDL32R400A. I added notes and an image of the antenna I was using for that test,



The signal strength scale has a very wide range with one dB steps.


If you can not measure it, you can not improve it.
Lord Kelvin, 1883
rabbit73 is offline  
post #30 of 41 (permalink) Old 2017-09-22, 10:59 PM
DHC Supporter
 
Join Date: May 2010
Location: S.E. VA
Posts: 687
My other 32" Sony, a KDL32BX320 also will MAX out on the signal strength scale at 0 dBmV:



but it is still useful:

picture freeze; signal could not be decoded because of multipath



signal is strong enough, but notches in scan suggest multipath interference:



a reflector was added to the folded dipole to reject multipath reflections:



and the scan looks much better:



The antenna was moved to a better location and the reflector wasn't needed:



better scan and stronger signal


If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2017-09-22 at 11:31 PM.
rabbit73 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Canadian TV, Computing and Home Theatre Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome