Re: Interference

Paul Zoba, W7PEZ

Nicely done!

On Jun 12, 2020, at 11:09 AM, Paul Butzi (W7PFB) <w7pfb@...> wrote:

I think I’ve got this nailed down.

I was wrong about the signal width.  On the waterfall it looks to be about as wide as a normal signal.  But it is very clearly digital.

So.  Close examination gives me:
* sometimes signals are weak.  Sometimes the signal is surprisingly strong.  Hypothesis: I am seeing *different transmitters* on the same frequency.
* The signal looks like DSTAR on the waterfall.  It sounds like DSTAR when you listen on an analog FM receiver.

Aha.  These are the clues we need.

I go to repeaterbook.  I’m looking for a repeater with the INPUT frequency of 146.5, because I think I am hearing different transmitters transmitting TO the repeater.

Repeaterbook gives me this DSTAR listing: KF7CLD 147.5 -1MHz shift, located in Burien.

My conclusion is that we’re hearing DSTAR users working the KF7CLD 147.5 repeater in DSTAR mode.

-p W7PFB
73, Don’t forget to smile and have fun!

On Jun 11, 2020, at 2:33 PM, Paul Butzi (W7PFB) <w7pfb@...> wrote:

I don’t know about anyone else but I am hearing this intermittently, still.

Today I hooked an SDR and took a look.  I had expected to see a pretty wide signal, spread from maybe 146.4 up to 146.6

Rather to my surprise what I saw as a very narrow, very clearly digital signal centered *exactly* on 146.500.  I would say roughly half the bandwidth of an normal analog amateur FM signal.

Some of the time I hear a very faint CW tail after the digital portion of the transmission.  That really, really suggests it’s a VNBD amateur transmission of some sort, because I just can’t imagine some random signal terminating with a CW callsign ID.

Sadly, the CW id is too faint for me to copy.

-p W7PFB
73, Don’t forget to smile and have fun!

On Jun 2, 2020, at 4:43 PM, Paul Butzi (W7PFB) <w7pfb@...> wrote:

I’ve been monitoring.

I have two separate reports:

1.  At one point while I was mobile between Redmond and Fall City, I got what sounded like DMR or DSTAR, moderate signal strength.

2.  In Carnation, HEAVY interference on 146.5, but it sounded like very loud static, with no modulation.  The interference stretched from 146.450 or so all the way up past 146.550, strongest at 146.51 or so.  As I drove from Carnation to my place, the strength of that interference faded.  I get about two bars at my house.

If someone could take a look at a panadapter when they hear the interference, well, it would be mighty nice to know how wide the different signals I heard are.

If it’s DMR or DSTAR then the bandwidth occupied is going to be narrow.  What I heard entering Carnation was really, really wide - 100KHz at least.  Or at least I could pick it up on my Kenwood D710G across a range that wide.

-p W7PFB
73, Don’t forget to smile and have fun!

On Jun 1, 2020, at 6:21 PM, Rowland <rowland.brasch@...> wrote:

When I monitored the noise on 146.500 it hit me at S9 plus and was very loud.



On Mon, Jun 1, 2020 at 5:24 PM Paul Butzi (W7PFB) <w7pfb@...> wrote:
146.500 is in the VNDB repeater output allocation in the WWARA plan.  I was pretty sure there was a DMR repeater there so I looked and sure enough, there’s a DMR repeater listed in the coordinated plan, callsign AF7PR.  

If it’s doing CW ID, just knowing whether it’s IDing as AF7PR would give us a big clue.  I think the repeater is supposed to be way the heck up near Bellingham, which seems like a long shot to the Sno Valley.

-p W7PFB
73, Don’t forget to smile and have fun!

On Jun 1, 2020, at 5:11 PM, Tom WA7TBP via <tomwa7tbp@...> wrote:

Hello all:

I would like to point out that on 146.500 MHz, there is a strong digital signal. I believe it could be a digital paging signal. It is intermittent, but sometimes can last for several minutes. I have heard a Morse code ID once in awhile, but have not been in a position to copy the code. Please take a listen and see if you hear the signal. Rowland and I have both heard it. If you can get any information about this signal, let me know and I will do what I can to get some time of action started to rectify the situation.

Thank you in advance for taking a listen.



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