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General Scanning Discussion For general questions not specific to a model of scanner or general discussion of use of a scanner. Location specific posts should be directed to the regional forums listed below.

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Old 11-25-2012, 2:50 PM
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Default P25 Trunked Simulcast recieve

The area I live in switched to a statewide P25 trunked system, and the towers in the metro area are simulcasting which is not always playing well on the scanner. Here's my question (in case someone has tried this already, or knows a better fix):

Would the recieve signal improve by cutting an 800 MHz yagi and directing it at the tower farthest away from the rest, in hopes of isolating it and cleaning up the signal? I'm not worried about picking up other bands or towers with that reciever, so thats not an issue.

Any experience with this would be appreciated before I sink money into an idea.

thanks
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Old 11-25-2012, 2:57 PM
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Quote:
Originally Posted by kc8kek View Post
The area I live in switched to a statewide P25 trunked system, and the towers in the metro area are simulcasting which is not always playing well on the scanner. Here's my question (in case someone has tried this already, or knows a better fix):

Would the recieve signal improve by cutting an 800 MHz yagi and directing it at the tower farthest away from the rest, in hopes of isolating it and cleaning up the signal? I'm not worried about picking up other bands or towers with that reciever, so thats not an issue.

Any experience with this would be appreciated before I sink money into an idea.

thanks
I think the #1 thing you need to do is omit [or significantly cut the signal strength] of as many of the simulcast sites [as seen at your antenna]. However you can manage that best is the way to go.

For some it may be best to direct a yagi right at the closest tower. For some it might be to orient the yagi in such a way that the vast majority of sites are off the back/side of the yagi.

A difficult example for me is the West Virginia SIRN simulcast sites in Ohio Co, West Virginia. In all cases they are basically in the same direction from me. I cannot point my yagi toward any one tower and effectively null out enough signal from one of hte other ones. In my case, I usually get he best performance by pointing my yagi about 20-30 degrees north of the closest site (which is sw of me). And the null at the side seems to cut down on the other sites enough to give me a decent decode.

It's a challenge for everyone. But I think you're on the right path using a yagi. If you get a decent signal on it from within your house on a ducky antenna as a general rule, you might not even want to put the yagi outside [too much signal to capture from all sites]. You might want to put it in a corner of your house and point it directly at the closest tower site and try to use some fancy tinfoil setup to block signal from everywhere but where the yagi is pointing, if your situation is severe enough to require that.

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Old 11-25-2012, 5:35 PM
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I monitor the ILL-Starcom State P25 system...In my area i can hear three of the towers within 5-25miles very well using the RS 20-176 25-1.3 grnd-plane ant's in my attic with LMR400 coax...My antennas out on the tower don't do a very good job because of multi-path or simulcasting of the system overload...I have a tri-level home and on my H/H scanners upstairs the RS 800 duck in spots does well...Its a tough game digital multipath towers but i think your beam should do well....
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Old 11-26-2012, 5:30 PM
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At home it was near impossible for me to scan the county simulcast system because of multipath distortion. A yagi may work for you and I nearly tried that as well, but decided to build something myself to see how that turned out.

I've been listening like this for months now, and after much tweaking of my antenna's direction, frankly its perfect. Now when I get distortion my first thought is its the fault of the transmitting radio, and most of the time that is confirmed by the person on the other end of the conversation. That's how well its been working for me.

Building antenna to scan P25
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