Multi-path Issue/Intermittent Reception Problem

wperry1 · 6-Jun-2011, 6:16 PM

Hi everyone,

I am new here but wasn't able to find any threads that seem to address my issue.

I live just outside Portland, OR and have LOS to my local towers at ~4 mi.

Here is a link to my Signal Analysis results
Current Setup ~15': http://www.tvfool.com/?option=com_wr...2193e1300b87a9
Attic/Roof Option ~25': http://www.tvfool.com/?option=com_wr...21930ab63b50f5

I am currently using a simple dipole from speaker wire (i know, i know, I'm cheap) in to my TivoHD. 90% of the time I get 90%+ signal on all the stations I care about (43, 40, 8, 10, 12, 22, 33, 30) but the other 10% never seems to happen when I am watching live TV so I can't see what the signal looks like at that point. Our top channels are 43, 40, 8, and 21 and they have all had the problem as some point. Adjusting the antenna seems to move the problem from channel to channel.

So, now that I have detailed my problem, my question is, does this sound like multi-path distortion, other interference, or something else entirely? What are my options for the most likely cause of the problem.

PS: About an hour ago, I threw together a single bow-tie antenna with no reflector which is now using shielded RG6 to get to the TV ( <6ft cable ). I am seeing slightly higher signals than with the old antenna 95%+ but I have no idea what to expect when it starts recording later.

Thanks in advanced for any help. From the posts I have read so far you guys have a good group here!

PPS: I just found a more detailed signal information screen on my Tivo which shows the Signal Strength in the high 90s and SNR between 29 and 32 for to channels mentioned above.

John Candle · 6-Jun-2011, 7:51 PM

Is this a , warehouse , a shop , house , condo , high rise , apt. , basement , mobile home , motor home , etc.?? If above ground - how many floors?? Is the building wrapped with any type or kind of metal such as but not limited to metal siding?? Are the walls made of poured concrete?? Is there brick from ground to roof?? Does the building have a metal roof??

John Candle · 6-Jun-2011, 7:56 PM

Read and understand this about , REAL Digital Broadcast Tv Channels , Virtual Digital Broadcast Tv Channels , Analog Broadcast Tv Channels , http://forum.tvfool.com/showthread.php?t=695

wperry1 · 6-Jun-2011, 8:35 PM

Quote:

Originally Posted by John Candle

Is this a , warehouse , a shop , house , condo , high rise , apt. , basement , mobile home , motor home , etc.?? If above ground - how many floors?? Is the building wrapped with any type or kind of metal such as but not limited to metal siding?? Are the walls made of poured concrete?? Is there brick from ground to roof?? Does the building have a metal roof??

Sorry I left that out. I am in a 2 story house with lower story being half under gound. The TV and antenna are on the second floor so the antenna behind the TV is about 15' off the ground. The TV is at the NW corner of the house with the back facing N so there is clear shot (except the wall) to the towers. The walls from inside to outside are Drywall , 2x4 and thin insulation, Plywood, Wood siding. The rest of the house is wood construction, no metal aside from nails, pipes, and wires. (there are no pipes in the wall in question).

Also, per your reference to the issue with virtual vs real channels, I have updated my original post with the real channels for the stations I am concerned with.

Thank you for your reply and please let me know if you need any more info.

John Candle · 7-Jun-2011, 8:30 AM

The television transmissions are VERY STRONG Do Not use any type or kind of amplifier. Here are indoor antennas to use , http://forum.tvfool.com/showthread.php?t=233. Point the Tv antenna at about 40 degree magnetic compass. Here is how to aim Tv antennas , http://www.kyes.com/antenna/pointing/pointing.html The transmissions are so strong that I recommend variable attenuator , Antennas Direct , model number 1296F , to Dial Down the signal strength and the multipath signal strength.

wperry1 · 8-Jun-2011, 6:37 PM

Quote:

Originally Posted by John Candle

The television transmissions are VERY STRONG Do Not use any type or kind of amplifier. Here are indoor antennas to use , http://forum.tvfool.com/showthread.php?t=233. Point the Tv antenna at about 40 degree magnetic compass. Here is how to aim Tv antennas , http://www.kyes.com/antenna/pointing/pointing.html The transmissions are so strong that I recommend variable attenuator , Antennas Direct , model number 1296F , to Dial Down the signal strength and the multipath signal strength.

Thank you. I have a local electronics shop where I can pick up attenuators so I'll try that first and look to order a directional antenna if that doesn't do the trick.

John Candle · 8-Jun-2011, 10:35 PM

If you will like to install a outdoor roof top Tv antenna then I suggest the Winegard HD7000R. And keep the variable attenuator handy to dial down those strong signals. If you use a outdoor antenna , ground the coax with a coax grounding block. The place to ground to is the house ground rod. The next best place to ground to is a cold water pipe , it must be real metal pipe not plastic. Grounding the shied of the coax directs unwanted signals to ground. Homedepot and Lowes have all manner of grounding supplies.