WJST-X Slice A Filters Do Not Change Waterfall

  • 1
  • Question
  • Updated 2 years ago
I have set up WJST-X  for my 6700 and have made many FT8 mode DX contacts in my first evening.  There was one weak station up around 2500 and some nearby very red stations.  So I tried to adjust my slice filter to a custom narrow window from 2400 - 2800.  I could hear the nearby stations had disappeared however the waterfall on WSJT-X still showed the same cluttered nearby red stations and the decoding did not change even for signals on the other end near 500... everything looked exactly the same.  My DAX Slice A RX gain is peaking well below 0.

Any advice appreciated. 
Photo of jerry stern

jerry stern

  • 23 Posts
  • 12 Reply Likes

Posted 2 years ago

  • 1
Photo of Mark WS7M

Mark WS7M

  • 505 Posts
  • 155 Reply Likes

The only thing I can think of is that the waterfall in WSJT-X is averaging.  Perhaps given some time the signals might have faded.  Not entirely sure about this.

I have never tried adjusting the filter.  My understanding of WSJT modes is that they are designed to work in cluttered bands and the algorithm picks out the various signals it needs to see.
Photo of John Culliton

John Culliton

  • 7 Posts
  • 0 Reply Likes
In my experience, strong signals near a very weak signal can just make the weak signal undecodeable. I’ve never been able to use the filtering to pull out a weak signal. Happens quite often and sometimes it’s just plain qsb. The software does quite a good job but with strong stuff nearby sometimes the weak transmission gets lost.
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

  • 9399 Posts
  • 3640 Reply Likes
I know for an absolute certainty that changing the slice RX filter bandwidth when connected to Fldigi via DAX shows an immediate, accurate and visible change the in the FFT waterfall display.  Not sure about WSJT-X, but if it isn't changing, I would suspect WSJT-X is responsible for the behavior and not DAX.
Photo of Don, VE2HJ

Don, VE2HJ

  • 38 Posts
  • 2 Reply Likes

Hi Jerry,

Often i use the traking notch filter to get rid of the +15dB and more signal. I see the change in the WSJT-X waterfall. But it is difficult to seperate to signal side by side -22 and +15. Most of the time i lose the weak one.

Photo of John Culliton

John Culliton

  • 37 Posts
  • 3 Reply Likes
" Most of the time i lose the weak one. " Agreed. Yes the filter selection does show on the waterfall for sure.