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DMR Interference on 435.350

Clint Bradford
 

Recently there has been a DMR signal QRM'ing the AO-92 uplink on 435.350 or close by. Hotspots, repeaters, terrestrial simplex (anything not satellite) should not be in 145.8-146.0 or 435-438 by international bandplan. Please QSY these radios ASAP. Please pass this info around - thank you!

- de AMSAT-NA

PETER HEAD
 

I’d never use a satellite frequency for that.

One of the issues here is a lack of established frequencies for hotspots and digital voice simplex frequencies. At least there is some minimal guidance for the latter.

Then when people ask they get unhelpful answers like ‘check the band plan’ or ask your local coordinator. I’ve done both of those and the band plan mentions packet/digital, which is in some cases also the satellite sub band. I’ve seen people recommend using sat frequencies and people think it’s actually ok, the justifications are mind blowing.

Frequency coordination isn’t helpful in my area, it’s a mess.  I live adjacent to 2 coordinating bodies and not far enough from a 3rd to be insignificant. Plus they are only ‘coordinating’ repeaters here anyway, no mention of anything else. The interference is a joke sometimes.

In any case I’m still in search for a good frequency for said things. I haven’t turned on my hotspot since I’m listening trying to find something free, and I’m surrounded by iron mountains.

Just an observation!
-Peter


--
KC2ASA (active on APRS - try Voice Alert or send a MSG)

On Aug 27, 2018, at 14:48, Clint Bradford via Groups.Io <clintbradford@...> wrote:

Recently there has been a DMR signal QRM'ing the AO-92 uplink on 435.350 or close by. Hotspots, repeaters, terrestrial simplex (anything not satellite) should not be in 145.8-146.0 or 435-438 by international bandplan. Please QSY these radios ASAP. Please pass this info around - thank you!

- de AMSAT-NA

WA1RJJ
 

Here in Connecticut, we have a very well-developed and largely adhered-to DMR frequency band plan ( http://www.ctares.org/CT-ARES_DMR_Network_Info_12July17.pdf ); that said, the recent boom in mobile/personal DMR hotspots is raising havoc with the status quo, even to the point where some new/rogue Brandmeister DMR operator can bring our network to it's knees.  It's rather bizarre that somebody is operating in DMR mode around 435.xxxMHz - he himself would suffer from normal satellite traffic.  It almost sounds deliberate.  Time to team up with your local club and "foxhunt" this guy down.


On 8/27/2018 3:32 PM, PETER HEAD wrote:
I’d never use a satellite frequency for that.

One of the issues here is a lack of established frequencies for hotspots and digital voice simplex frequencies. At least there is some minimal guidance for the latter.

Then when people ask they get unhelpful answers like ‘check the band plan’ or ask your local coordinator. I’ve done both of those and the band plan mentions packet/digital, which is in some cases also the satellite sub band. I’ve seen people recommend using sat frequencies and people think it’s actually ok, the justifications are mind blowing.

Frequency coordination isn’t helpful in my area, it’s a mess.  I live adjacent to 2 coordinating bodies and not far enough from a 3rd to be insignificant. Plus they are only ‘coordinating’ repeaters here anyway, no mention of anything else. The interference is a joke sometimes.

In any case I’m still in search for a good frequency for said things. I haven’t turned on my hotspot since I’m listening trying to find something free, and I’m surrounded by iron mountains.

Just an observation!
-Peter


--
KC2ASA (active on APRS - try Voice Alert or send a MSG)

On Aug 27, 2018, at 14:48, Clint Bradford via Groups.Io <clintbradford@...> wrote:

Recently there has been a DMR signal QRM'ing the AO-92 uplink on 435.350 or close by. Hotspots, repeaters, terrestrial simplex (anything not satellite) should not be in 145.8-146.0 or 435-438 by international bandplan. Please QSY these radios ASAP. Please pass this info around - thank you!

- de AMSAT-NA


Clint Bradford
 

PETER HEAD
 

That document is at least somewhat helpful. But the Texas band plan doesn't go below 440. And also it's mentioning which frequencies to avoid instead of suggesting the frequencies to use. The ARRL band plan requires some knowledge to interpret. Some people will have no idea what OSCAR is.
I just came upon an interesting problem, I just started to setup my SharkRF openSPOT and it's default frequency is 436.000. Ugh. Now to figure out where this thing belongs, is it a repeater (not really), simplex (sort of), experimental (hmm, think it's past that point). This is why people just pick a frequency with a dart, it needs to be more cut and dry.
-Peter

--
KC2ASA (active on APRS - try Voice Alert or send a MSG)
Skywarn Spotter# 13-249NYC
Wx station: http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KNYSLOAT1