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-   -   Co-channel interference (http://forum.tvfool.com/showthread.php?t=16707)

BrianHawthorne 15-Dec-2019 9:16 PM

Co-channel interference
 
Hi, new to OTA, please excuse me if this is a dumb question. Iíve got a Channel Master 2018 temporarily sitting in a 2nd story bedroom. Pointed 39 degrees magnetic. From there I have a 10 foot section of RG6 going into a Tablo Dual Lite. The tablo is on my WiFi. Doing this as a test, Iíll later install the antenna in my attic, running the coax into a second story bedroom into the Tablo. Donít want to do a roof mount of the antenna.

Hereís my radar map plot:
http://www.tvfool.com/?option=com_wr...903834f43ccf55

I get ABC, NBC now and some other channels. Iíd like to get WFSB, but canít. Report shows co-channel interference. Iím not sure, but maybe the interference is with WTIC, I donít need WTIC. Is there a way to cure the co-channel interference issue? Thank you!

GroundUrMast 15-Dec-2019 10:49 PM

You're correct, there is some potential for co-channel interference... However it looks as if there is enough difference in signal levels (20 dB or more ) that it's reasonable to hope for reception of WFSB.

To be successful, you may need to mount an antenna outdoors, above tree top level. I would also expect to need a full sized UHF antenna or combination UHF/High-VHF. The terrain between you and Hartford forces you to use a substantially larger antenna than you would need if there was a clear line of sight.

the Winegard HD7698P would be a full size combo to consider. One could also combine the 2018 with an Antennas Direct DB8e... Using a UHF/VHF combiner, the DB8E would connect to the UHF port and the 2018 to the VHF port.

rabbit73 15-Dec-2019 11:28 PM

1 Attachment(s)
Quote:

Originally Posted by BrianHawthorne (Post 62512)
Hi, new to OTA, please excuse me if this is a dumb question. I’ve got a Channel Master 2018 temporarily sitting in a 2nd story bedroom. Pointed 39 degrees magnetic.
Here’s my radar map plot:
http://www.tvfool.com/?option=com_wr...903834f43ccf55

I get ABC, NBC now and some other channels. I’d like to get WFSB, but can’t. Report shows co-channel interference. I’m not sure, but maybe the interference is with WTIC, I don’t need WTIC. Is there a way to cure the co-channel interference issue? Thank you!

Hello, Brian. Thank you for the report. You do have co-channel interference, but it is now different because of Repack channel changes.

WFSB has co-channel interference on real channel 36 from WCBS also on 36. WFSB is only about 4 dB stronger than WCBS; it needs to be at least 16 dB stronger. However, since WCBS is in the opposite direction, a high gain directional UHF antenna with a good Front to Back ratio should make WCBS weaker.

This report from rabbitears.info is probably more up to date:
https://www.rabbitears.info/searchma...study_id=35520

This is an extract from that report:

https://forum.tvfool.com/attachment....5&d=1576456127

If you try the 2018 in the attic aimed at WFSB and still don't get it, there are several other things you can try.

The first would be to put a large sheet of cardboard covered with aluminum foil behind the 2018 to block the WCBS signal from the rear.

If that doesn't work, then you will have to do something more complicated like GroundUrMast suggested.

I suggest a two antenna solution. Use the 2018 as a VHF antenna without a preamp, and use an Antennas Direct 91XG or Solid Signal HDB91X with a preamp for UHF. You could try the DB8e for UHF, but the yagi antennas have a higher F to B ratio.

Combine the VHF antenna with the UHF antenna and its preamp with an Antennas Direct UVSJ UHF/VHF Combiner. That UVSJ will pass power to the UHF preamp.
https://store.antennasdirect.com/UHF...Combiners.html

The VHF antenna doesn't need a preamp for ABC.

I can't guarantee that will work with all those trees, but I think it's you best chance if you can't go outside.

Code:


UHF Ant > preamp >
                  \
                UVSJ > coax > power inserter > TV
                  /
    2018 for VHF >


GroundUrMast 16-Dec-2019 2:59 AM

My previous estimate of your location may be inadequate... It would be helpful if you could generate a signal prediction using the search tool at rabbitears.info, https://www.rabbitears.info/searchmap.php

BrianHawthorne 16-Dec-2019 10:07 PM

Thanks
 
GroundUrMast, Rabbit73,
Gentlemen thanks for the in depth information. I plan to start with the aluminum foil trick, to see what happens, and take it from there.
GroundUrMast,
I ran my lat-long through rabbit ears, hereís the link
https://www.rabbitears.info/searchma...study_id=35895

Thanks again,
BrianH

GroundUrMast 17-Dec-2019 1:27 PM

Thanks for posting the additional prediction... My estimate of you position was off target apparently. It looks as if rabbit73 did a better job. Please keep us informed on your progress.


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