Co-Channel and Signal Power how much db difference is necessary
I have a few co-channels in my area and a couple of the stations are ones I want to get.
The problem is that the station I would like to get only gives me 10db to my area but its co-channel station is much weaker at -7db... is there any rule of thumb to know when trying to get a station if its worth trying a bit more or if a co-channel is just going to knock it off the air. 17db is not that great a difference its not like one is 60db and the other -20db I have a few of these type stations and normally one is above and one is below zero but many of the stations i get here are weak and under 20db so i am fighting things.. I want to get abc from one direction and the rest of my lineup from another but some of the cochannels are in the direction of that abc station.... then again i just looked through the zap2it guide for ABC and that station is mostly garbage now heh maybe i can do without it.. but they do play some sports on the weekend and maybe one or two shows in prime time. anyway is there any rule of thumb? or is this pretty much factored into the results page and anytime there is a C you are going to get knocked off |
The directions the stations are located and the type of antenna you have play a key role in this. It would be helpful if you could post your TV Fool report, the make and model of your antenna/preamp and the particular stations you are referring to.
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The general rule for co-channel interference is that your desired signal must be at least 15.5 dB stronger than any other signal on the same channel.
ATSC Recommended Practice: Receiver Performance Guidelines Document A/74:2010, 7 April 2010 RECEIVER PERFORMANCE GUIDELINES 5.4.1 Co-Channel Rejection Quote:
The general rule for adjacent channel interference is that your desired signal must not be any weaker than 33 dB as compared to the signals on either side of it. 5.4.2 Adjacent Channel Rejection Quote:
These rules assume that the signals are in the same direction, they don't take antenna pattern into consideration, and there aren't any spurious signals created by IMD (Intermodulation Distortion) from strong signal overload (as ADTech said). Quote:
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excellent and thank you especially rabbit for digging that up i know it takes a bit of time to do that...
on a couple channels I would like i am very close to that 15.5 but hopefully enough that i can at least try to get signals from 2 directions and it won't knock off my philly fox station.. if not i might actually pickup another fox from baltimore and that one comes with a 24/7 weather station and Sports Network.. did a little testing today .. i might end up getting one of those 8bay uhf antennas that you can point each side in different directions.. one side would be at 31magnetic for philly and the other side at 275 magnetic for baltimore. Right now i have a ClearStream 4v and get channel 12 from philly about 55miles away.. i get 3bars when i pair it with a ChannelMaster 7777 (yeah i can hear ya) a db8e would be wonderful i guess but maybe my budget can only afford a Xtreme Signal HDB8X-NI http://www.amazon.com/Xtreme-Signal-.../dp/B00CXQO00K or a Steller labs Dual Quad Bay Outdoor http://www.amazon.com/Dual-Outdoor-B.../dp/B00DHHMOUW I really like Stellar labs db rating on that thing hahahaha hey who knows though heh but if i can find a deal and they come around once in a while for $50 i might give it a go with one of those three.. and my 7777 since you guys have been very nice with the info here is my report http://www.tvfool.com/?option=com_wr...f1f0bef57dd8d9 today I verified that I get Pointed at about 31degMag fox29philly at 5bars WHYY12 at 3bars WBOC marginal lock but ok once locked Pointed at about 275degMag WMAR i get 5 bars WUTB at one bar - grit tv WBFF 3 bars with weather station & ASN I have a snow storm coming in from the west about 3-5hrs out during testing sun was shining and nice might be getting a slight bounce off that snow storm. thanks again guys |
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