Unexplained dips in message rate?

I can’t remember which thread it was mentioned in before but I’ve had another couple of those odd drops in message rate earlier today (1st July 2022), one around 09:00 for about 90 minutes and another one a short while later.

Did anyone else experience the same thing? @caius @suffolk3000 @alleyoopie etc?

I had the same, located East London and Bedford also…

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Yes, I’ve noticed the same thing happening fairly often over the past few weeks at about the same time.

The odd thing is that there’s also a dip in DF17 messages which are transmitted without interrogation:

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I get same thing im on smart meter so could be that
4am my intercom goes mad but nothing on pic

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Me too, Greenwich.

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The airspy RSSI graphs might be interesting?

I suppose it could be interference … obviously @keithma was closest having the largest dips?

Was it accompanied with a range drop?

Much the same here. Not too far from you @keithma

Please excuse the noise… I’m mucking about with gain :slightly_smiling_face:

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They’re flat and no associated drop in range.

It’s unlikely to be your smart meter affecting us all :slight_smile:

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Again today, same effect noticed on all three receivers.

Aircraft numbers and tracks were unaffected.

Max range didn’t reduce either so I wasn’t losing distant signals.


And the signal level.

You have the gain with that?

It looks like weak signals were detected worse.
So that could be something like pulsed interference. (let’s say 60 % duty cycle)
You’d still get weak signals but at a much reduced rate.

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Gain is flat at 15.

Yes, it could be something pulsing, that would definitely explain the drop in messages but not a lot else - I imagine it’s affecting all the stations in the south of the UK and probably a chunk in the top left of Europe as well, I don’t specifically think it’s local here.

The MTG graphs are identical as are the ones from the RTL based receiver in my loft.

I can vouch for the same dips

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South coast?

My username is misleading :slight_smile: Southend

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i had the same dip in the midlands

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I had some dips in Wigan.

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I get it im in the triangle watisham , mildenhall, lakenheath

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Hove1 looks identicall hmmmm

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Yeah it’s quite widespread I think. I’ve been seeing that effect fairly often in the last few months. There is an increase in average signal strength seen during those periods, and also noise. The minimum noise doesn’t change much at all though:

SNR is pretty constant throughout:

I’ll to try and grab an RF sample if I happen to notice at a time when it’s happening.

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