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Old 01-26-2018, 8:47 AM
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Default DMR and Analog Repeaters on the same frequency

I'm not an amateur radio operator but have a question about something. I noticed yesterday an analog repeater (CWid N3VNG with a PL of 146.2) and an DMR repeater (CWid KB3UAG) use the same frequency of 145.2500. N3VNG is at Cascade MD on the MD/PA border and is about 30 miles +/- from KB3UAG which is at Saint Thomas PA. I also receive an CWid of KK3L as N3VNG is part of an linked system ( The Target Link System). Monitoring yesterday there wasn't an great deal of traffic on either repeater with talkgroups 3142 and 3172 being the only ones active on the DMR repeater. At times of greater activity wouldn't them being on the same frequency cause interference issues for the users of both repeaters?
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Old 01-26-2018, 9:04 AM
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Capture effect would dictate. FM analogue radios would receive the analog repeater. The digital radio would only open squelch with valid data stream.

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Old 01-26-2018, 10:39 AM
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Quote:
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Capture effect would dictate. FM analogue radios would receive the analog repeater.
Not necessarily. If the DMR signal was stronger, the analog radio would lock on to the digital noise.
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Old 01-26-2018, 11:42 AM
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If there are two repeaters on the same frequency that are 30 miles apart, then either the frequency coordinators failed to coordinate or somebody is running an un-coordinated repeater (which is allowed under Part 97).
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Old 01-26-2018, 12:16 PM
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Quote:
Originally Posted by BM82557 View Post
At times of greater activity wouldn't them being on the same frequency cause interference issues for the users of both repeaters?
Yes, where the coverage overlaps and when they are active.

Using a PL/DPL tone on the analog repeater output (RX side on the end users radio) would help, but around here many/most amateur repeaters don't run any sort of tone/code squelch on their outputs.

Wouldn't be surprising if this was some sort of amateur radio repeater owner "battle". I've seen this on the GMRS side and heard a few low-life amateurs purposely try to interfere with one another.
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Old 01-26-2018, 4:29 PM
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Since they are actually in different states, I wonder if the coordinating body is the same or different. Different coordinators could explain it.

Frank KK4YTM
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Old 01-26-2018, 4:36 PM
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Whenever a new technology comes along, there are those that who embrace it and those who are happy with the status quo.

Eventually DMR and other digital technologies will have their own subbands assigned to them.



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Old 01-26-2018, 4:39 PM
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Quote:
Originally Posted by FKimble View Post
Since they are actually in different states, I wonder if the coordinating body is the same or different. Different coordinators could explain it.

Frank KK4YTM
The coordination process is supposed to take that into account within a certain distance. On 2 meters, that's 120 air miles according to the coordination body for this area.
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Old 01-26-2018, 5:36 PM
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Quote:
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Eventually DMR and other digital technologies will have their own subbands assigned to them.
Maybe. On some bands, there simply isn't enough available spectrum to segregate the digital voice modes from the analog voice modes. And, if a coordinator did implement sub-bands, all of the trustees would have to understand that they might have to move in order to fit the new sub-band.

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The coordination process is supposed to take that into account within a certain distance.
I am the amateur radio repeater frequency coordinator for Indiana. When I coordinate a repeater, I send my proposal to the coordinators in the four states states that touch Indiana plus Wisconsin (northwest Indiana is relatively close to southeast Wisconsin). In my opinion, this is what coordinators are supposed to do. With some of the surrounding states, I have copies of their databases and they have a copy of my database so that when we search for an open frequency, we can see what might interfere from the other state.
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Old 01-26-2018, 7:08 PM
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RF is RF so yes interference on both analog and digital repeater systems in overlap areas will happen
.......
This is what happens when every ham wants to have their own repeater to boost their ego.
.......
So instead of having one or two excellent repeaters in an area there are dozens of lousy ones with zero activity
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Old 01-26-2018, 7:43 PM
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If they are that close I have to agree that one of them is most likely an un-coordinated repeater. Living in Maryland I know our Repeater Coordinators send new proposed repeater information the coordination groups around us to make sure no objections.
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