• 1
  • Question
  • Updated 2 years ago

I know...there were a lot similar questions but the major questions are 4 years old.

Any News about RTTY FSK and TWIN Peak filter Mode for RTTY for SSDR ?

Greatings from Cologne,

Sven, DF9MV

Photo of Sven Duhme

Sven Duhme

  • 1 Post
  • 0 Reply Likes

Posted 2 years ago

  • 1
Photo of Mike va3mw

Mike va3mw

  • 824 Posts
  • 199 Reply Likes

I watched a presentation by Stu Philips K6TU in Dayton about RTTY and filtering and essentially he clearly showed that the developers of the decoding software don't want twin peak filters.

I was as surprised as anyone else as anyone else.  

The developers want the passband opened up as much as possible.  I defer to the software developers for the details.

Mike va3mw
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

  • 9478 Posts
  • 3666 Reply Likes
For proper decoding of RTTY signals, the decoders need to receive the Bessel sidebands generated from both mark and space.  Using a filter that narrowly allows the mark and space signal to pass is removing that signal content.  At 140 Hz spacing, it is hard to get tight enough notch in-between the signals that don't eliminate the Bessel sidebands
Photo of Chris Tate  - N6WM

Chris Tate - N6WM, Elmer

  • 1017 Posts
  • 282 Reply Likes
Pretty much every top RTTY operator, including Ed Muns, W0YK recommend against use of this filtration technique.  Thats not to say that it doesnt have its occasional usefulness, but in general that would be a rare exception.  As it stands SSDR and the 6000 platform does an exceptionally good job at decoding rtty signals as it is implemented now.