Consitent breakup on PBS-HD via OTA

[Andy22]

I love the quality of the local PBS broadcast and especially the kids shows that are in highdef. However, I am getting a consistent but short breakup where the picture pixelizes, loses audio and then returns to normal. Happens every few minutes. The other OTA channels do not have this problem. I am using a $20 OTA antenna from Circuit City so it's definitely not the top of the line but it works ok on the other channels. Would I be better off getting a higher quality antenna?

Edit: I guess this may not be the best forum for this but this is where I "hang out" :)

[sr6376]

In all likelihood, a "higher-end" antenna would not solve your problem totally. I have a roof mounted antenna (from D*) and have pretty consistent "pixellation" issues on my OTA channels. I am in pretty close proximity to the local antennas, and am not completely convinced that the issue is not with the H20/HR20receiver itself. If your $20 OTA antenna works for you on everything else, stick with it IMHO.

[donshan]

I love the quality of the local PBS broadcast and especially the kids shows that are in highdef. However, I am getting a consistent but short breakup where the picture pixelizes, loses audio and then returns to normal. Happens every few minutes. The other OTA channels do not have this problem. I am using a $20 OTA antenna from Circuit City so it's definitely not the top of the line but it works ok on the other channels. Would I be better off getting a higher quality antenna?

Edit: I guess this may not be the best forum for this but this is where I "hang out" :)


A better place to find local OTA in Memphis would be on this AVS thread with about 164 pages(!) of info. Usually posters on these local threads know all the reception and antenna OTA issues in their area better than anyone, even the station engineers!:)

http://www.avsforum.com/avs-vb/showthread.php?t=167943&highlight=memphis

[shoelessjoe]

I love the quality of the local PBS broadcast and especially the kids shows that are in highdef. However, I am getting a consistent but short breakup where the picture pixelizes, loses audio and then returns to normal. Happens every few minutes. The other OTA channels do not have this problem. I am using a $20 OTA antenna from Circuit City so it's definitely not the top of the line but it works ok on the other channels. Would I be better off getting a higher quality antenna?

Edit: I guess this may not be the best forum for this but this is where I "hang out" :)

The tuner in the HR20 is just not as good as the tv's tuner. There are about 7 channels I get clear w/o any problems via the tv tuner, but some channels will not even come in with the HR20. I am assuming you are only using the HR20 tuner.

[Skins Fan]

I believe it is the HR20 or H20 also. My antenna HD locals are usually pretty good on my H20. When it is giving me persistent breakup, I check a TV with a Sony HD300 and it is rock solid. So, I just always chalk it up to the H20 acting up because it is getting a weaker signal for some reason.:confused:

[Andy22]

Thanks for the feedback guys. Now that you mention it I did not see the problem when it was hooked up straight to the tv :|

Thanks for the link Donshan...I will check that thread out.

[donshan]

Thanks for the feedback guys. Now that you mention it I did not see the problem when it was hooked up straight to the tv :|

Thanks for the link Donshan...I will check that thread out.

Good luck. :) Here is some general info I use locally on our OTA AVS thread for similar problems. Use any portion that applies since this subject takes a book to cover all the local issues.

The tuner in the HR20 does not "scan" for channels like the one in your HDTV. Instead it uses channels from a list downloaded from D* for your market that they support in the Guide to permit DVR recording. However feed the HR20 a good signal and it works OK, but no OTA tuners in satellite receivers are "top quality". Below I discuss multipath reflection problems. As each new generation of OTA tuner has improved, the error correction of multipath reflections has also improved, which may explain why your HDTV works and your HR-20 does not on this one channel. Does the signal strength meter in the HR20 on that channel fluctuate up and down more than the others? If so read on- it may be a correctable multipath problem.

Except when the station itself has digital problems ( which happens too often) I get 95-100 % signal strength on my HR10-700 and flawless OTA reception from 5 local UHF band HD stations using a roof mount 4 bay bowtie UHF antenna (Antenna Direct DB-4) from towers about 10 miles away. Two bay and eight bay types also are available for different distance ranges. Where your digital channels are only in the UHF band ( check antennaweb.org) I feel this bowtie back reflector antenna type is both economical, easy to install and very effective. Unfortunately in my area BB, CC, and RS do not carry this type of antenna which are made by Channel Master, and Antennas Direct and others, but they are widely available on the web. These links have pictures of the types I am referring to:

http://www.solidsignal.com/prod_display.asp?prod=AD-DB4

http://www.solidsignal.com/prod_display.asp?PROD=ANC4228

http://www.solidsignal.com/prod_display.asp?PROD=ANC3021

The Silver Sensor and the DB-2 are good indoor or attic antennas for areas close to the towers and high signal strength.

http://www.solidsignal.com/prod_display.asp?prod=ZHDTV1

When pixelation issues persist even with a good antenna- antenna pointing direction to the station OR multipath reflections are two issues often involved.

1. If your stations do not all come from one direction within at least a 90 degree beam width arc ( the beam width of the 8 bay is very highly directional at only 15 degree beam width) then it is impossible to pick up all well without a rotor. Also if you also have VHF digital channels a different antenna design of the combo VHF-UHF type is needed. check antennaweb.org for digital channels and direction.

2. Multipath is the digital equivalent of ghosts in old analog TV and it can sometimes help to hook up an old analog TV and tune an analog UHF station near your digital channel to see if there are ghosts. (If I have it correct your PBS WKNO 10 is actually broadcasting on UHF channel 29). Multipath is commonly caused by reflections off of nearby hills or tall buildings , but can also be caused by misalignment of the antenna and in attic installs reflections off of metal ducts or brackets in the attic or other reflections from the rear such as your roof. When it occurs it is deadly to OTA reception. I once got it only on one channel when the wind rotated my antenna out of alignment. If your signal strength on that channel is fluctuating more than +/- 3 to 5 I would suspect multipath could be causing the dropouts on the dips. The cure is a better back reflector on the antenna, a more directional antenna, relocation of the antenna, or better pointing. In the UHF band even 5 to 10 feet relocation can make a difference. Using the narrow beam width of the 8 bay type could also be a cure where a hill or building reflection is involved.

This is a complicated subject only skimmed here. Again the AVS local forum threads have the best local details especially for areas with BOTH UHF and VHF digital channels, and note that some stations now using UHF are going to revert to their old VHF channel after the Feb, 2009 cutoff which could render an antenna obsolete. Check your local station's plans.

Rant warning: There is no such thing as a special HDTV antenna. Each channel frequency requires a different length antenna element to receive it perfectly so bow tie and log-perodic antenna types do best. Many antennas sold in the major chain stores use a single loop or one rod with a built in amplifier then try to defy physics and are a ripoff IMHO. The old style multiple element UHF, log-periodic, and yagi antenna types developed 50 years ago are still the best HDTV antennas and amplifers usually hurt more than they help except in deep fringe areas where low noise preamps help.

[bobnielsen]

Another factor is that PBS stations tend to cram several subchannels into the digital signal, which can result in increased problems. KCTS in Seattle used to time-share between HD and a Kids subchannel. They dropped the latter when the HD subchannel went full-time (they also switched the HD version from 1080i to 720p). They have since added a Spanish-language subchannel and it makes a (slight) difference.