Strong broadcast signal fades in and out. Why?

Brucemck2 · 8-May-2013, 11:59 PM

I am not sure whether I am having antenna size issues or antenna mounting location issues or tuner hardware issues, or something else.

I have a pretty new Tivo Series 4 that I use for my OTA tuner. My OTA antenna is a Channel Master 2016. It is mounted in a third story attic directly facing the broadcast antenna farm. No radiant barrier or similar inside the attic (foam insulation), although there are some HVAC flex ducts several feet away. No hills or major obstructions between the antenna and the broadcast stations. All major channels in my area are directly to the south, approximately 13 miles away, so the CM2016 should be more than adequate.

My TVfool link: http://www.tvfool.com/?option=com_wr...1dda24dbfb3f4b

Here is my issue:

Most of the major channels, except for KPRC (NBC on RF Channel 35) have great signal strength and corresponding SNR. Most channels read 40+ signal strength and 20+ SNR on the Tivo's signal strength meter. When I watch the meters signal strength fluctuates a point or two, but not more than that.

However, KPRC (NBC RF 35) has a wildly fluctuating signal strength and SNR. Over a two minute span I observed 55, 20, 0, 46, 57, 30, 0, 48 for signal strength (with corresponding SNR of 24, 12, 0, 21, 25, 14, 0, and 22). There was no wind or rain. That channel has "stuttering" and "breakup" on the picture and sound, corresponding to the signal fluctuation, and is not watchable for more than a few minutes as a result.

I get inconsistent results on RF channels slightly above and below KPRC RF 35. I get a very high signal strength reading, above 65, from KIAH (CW on RF 38). I get very low and fluctuating signal strength from KPXB (ion RF 32) and from KFTH (Univision RF 36), in a range that fluctuates between zero and 24 for both stations.

Based on the above do you think I have too small an antenna, or, interference from the HVAC ducts/location, or Tivo tuner hardware problems, or something else?

Brucemck2 · 9-May-2013, 2:33 AM

I am not sure whether I am having antenna size issues or antenna mounting location issues or tuner hardware issues or something else.

I have a pretty new Tivo Series 4 that I use for my OTA tuner. My OTA antenna is a Channel Master 2016. It is mounted in a third story attic. No radiant barrier or similar inside the attic (foam insulation), although there is some HVAC flex duct a few feet away. No hills or major obstructions between the antenna and the broadcast stations. All major channels in my area are directly to the south, approximately 13 miles away, so the CM2016 should be more than adequate?

My TVfool link: http://www.tvfool.com/?option=com_wr...1dda24dbfb3f4b

Here is my issue:

Most of the major channels, except for KPRC (NBC on RF Channel 35) have great signal strength and corresponding SNR. Most channels read 40+ signal strength and 20+ SNR on the Tivo's signal strength meter. When I watch the meters signal strength fluctuates a point or two, but not more than that. The picture quality on all of those is terrific.

However, KPRC (NBC RF 35) has a wildly fluctuating signal strength and SNR. Over a two minute span I observed 55, 20, 0, 46, 57, 30, 0, 48 for signal strength (with corresponding SNR of 24, 12, 0, 21, 25, 14, 0, and 22). There was no wind or rain. That channel has "stuttering" and "breakup" on the picture and sound, corresponding to the signal fluctuation, and is not watchable for more than a few minutes as a result.

I get inconsistent results on RF channels slightly above and below KPRC RF 35, all of which come from the same general transmission area. I get a very high signal strength reading, above 65, from KIAH (CW on RF 38). I get very low and fluctuating signal strength from KPXB (ion RF 32) and from KFTH (Univision RF 36), in a range that fluctuates between zero and 24 for both stations.

Based on the above do you think I have too little gain on my antenna, or, interference from the HVAC ducts/location, or Tivo tuner hardware problems, or something else?

elmo · 10-May-2013, 1:45 AM

Hmmm. I don't have a clue. Have you ever tried the antenna outside? To rule out the attic. How's the coax run? Maybe try a direct test run to rule that out?

ADTech · 10-May-2013, 5:42 PM

You have multi-path that's affecting the frequencies at and around channel 35. Move the antenna several feet away and start over. Repeat as needed until you find a spot where the signals cooperate.

13-May-2013, 11:34 PM

Tivo's are Known to have on going tuner issues.

Tivo tuners do not cope well with less then perfect digital broadcast tv signals.

---->ALL digital broadcast tv signals are less then perfect.<----

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As a Test of reception.

Connect the antenna directly to a Digital Tv , bypass the tivo Completely.

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Attics Are Not a reception friendly environment and Never Will Be a reception friendly environment.
Multi-path/reflections , absorbing , blocking , Tv reception.

Also the Houston area has many - moving multi-path issues due the airplane flight paths.

The airplanes are metal , The Tv transmissions bounce off the metal and are reflected at all manner of angles to your receiving antenna.

This moving multi-path is not good for reliable reception.

Digital Tv Tuners can compensate for and correct multi-path to certain point and then the digital tuner is overloaded , the tuner tries to lock on , loses the lock , the signal strength and quality readings , jump up and down up and down , resulting in pixelation and the screen goes blank.

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Try relocating and aiming directions the antenna in the attic.

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The signal strengths are plenty strong at your location.

Do not use any type or kind of preamplifier or distribution amplifier or any other type or kind of antenna system amplifier.

A amplifier will amplify the problems and make the reception worse.

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Also try locating the antenna above the roof in such a manner that the roof and house are not blocking reception to the , south and east and north west.

First try aiming the antenna at the south group of Tv stations at 186 degree magnetic compass direction.

Try aiming the antenna at a in between aim direction of the south group and east group of Tv stations at about 136 in between degree magnetic compass direction.

Here is how to aim antennas , http://www.kyes.com/pointing/pointing.html.
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As always , the starting antenna aim direction is the --> starting antenna aim direction.

The aim direction can be adjusted for best reception.

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Most Digital Tv's have a signal strength meter and some Digital Tv's have also have a signal quality meter.

If the Tv has a signal quality meter , locate and adjust the antenna for best signal quality.

Brucemck2 · 15-May-2013, 11:54 PM

Appreciate the help ...

Can anyone recommend a good OTA tuner that has a remote control? Ideally it will have ability to record, HDMI output, and rs232 too.

16-May-2013, 6:41 AM

Channel Master is top of the line.

http://www.channelmasterstore.com.

Has stand alone digital tuners with dvr and more.

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ePVision is Top Of The Line.

http://www.epvision.com.

Has stand alone digital tuners with dvr and more.

ADTech · 16-May-2013, 4:46 PM

Not too many choices. Magnavox (Funei) makes one or two. Channelmaster, I think has an offering. ePVision PHD-VRX is out there. Haven't used any of them personally.

Beyond that, you'd have to get into the PC-based or networked stuff.