Query re MSK burn image

[VK4ADC]

In the image from Fast Graph in WSJTX below, there is an angled 'burn' effect that I have never managed to find an explanation for.  For compactness, the burn image is overlaid with the time date and freq from WSJTX itself.   Yagi is typically at 210 degrees as it is during MSK operations to work South (eg VK1,2,3,7).

   

Seeing that it is a new year I think it is time for me to find out.

I periodically see similar burns, always angled but can be either forward or backward, varying intensities and periods, always early in he morning before any local transmit activity starts (ie 5AM).

Anybody have any ideas ??

   
Reference image. Top is a local TXing, Lower is a normal MS burn display

[VK4CZ]

In the image from Fast Graph in WSJTX below, there is an angled 'burn' effect that I have never managed to find an explanation for.  For compactness, the burn image is overlaid with the time date and freq from WSJTX itself.   Yagi is typically at 210 degrees as it is during MSK operations to work South (eg VK1,2,3,7).



Seeing that it is a new year I think it is time for me to find out.

I periodically see similar burns, always angled but can be either forward or backward, varying intensities and periods, always early in he morning before any local transmit activity starts (ie 5AM).

Anybody have any ideas ??

Absolutely no idea - have never seen the effect.

[ZL3RC]

Looking at the top Image it looks like a very strong signal passing across the frequency.
This would explain the slopping blob and its tapped ends as they are following the audio passband response (same as the noise)

But I guess your question is really what was the signal. Its not MSK that's for sure as its not occupying that signals spectrum.
My guess would be someone or something moving across the frequency.

HNY

Roger ZL3RC

[VK4ADC]

Thanks Roger.

Maybe it is a frequency sounder that passes across 6M ??  
I have seen it a number of times across the last few months, sometimes not as defined or strong, and sloping either way. Sometimes multiple "burns" in a given 15S period.

I will keep an eye out and try to make extra screen prints (cut-down) to add here. Enough of them might show a pattern develop.

[VK4ADC]

Spotted it again this morning MSK mode, 50.230, beaming 210 degrees from SEQld, and not just a single angled burn effect, and more of a V effect overall. It was visible in the previous period too but I was too slow to hit Shift+PrtScr to capture it.

This time around  :

   

So about 4-5 seconds between effects reduces likelihood that it is an ionospheric sounder as they seem to only do one pass across the freq (and it was there the previous period too)..  a quick 'zipfff' sound if you will.

Still an unknown..

[VK5PJ]

Hello Doug,
I think you have a wandering birdie some where in your area. While I do not run the MSK144 mode on 1.8 MHz I see a similar thing go through my waterfall here on FT8, strangely it only appears after I have transmitted for a short time and wanders up and down around my TX frequency. If I stop all activity it goes away but returns when I start to transmit. have never worked out what it is.

I would suggest you leave the RX volume up on the rig and see what is sounds like when it appears, it may give you a new insight as to its nature.