Poor RTTY decoding FLDIGI Signal Browser

Bill W2PKY

Signal Browser does not decode RTTY signals correctly most of the time , although occasionally a short stream of correct letters will appear. Using the latest version. 6300/DAX connection.
Main window is correct.
 

Andrew O'Brien

Squelch setting in Fldigi ?
Andy K3UK

np2g

Who says there all the same . 
No problem with DM780 .

Bill W2PKY

Squelch is at it's lowest setting -12. Have tried various signal levels in DAX. Does the signal have to be very strong to appear in the Signal Browser window?

np2g

Loaded Fldigi to see what you are talking about 

Perfect copy is only possible with  a strong station. The lesser the signal strength adjusting the squelch away from the  noise threshold(increasing)  will limit  random character  garbage  .

This is not a failure of Flex or any program  it's normal. 

So if you set the squelch  control UP to some level  higher than you have it now you will not be decoding  the Noise floor  . 

There is a break even point of decoding signal strength vs noise .

Also having your DAX (REC)  level too high  will also help produce random characters .

RTTY does not have FEC   forward error correction. So with weak signals 100 % copy is impossible .

The Flex  using Dax and just about any digi program  is just a super functional machine. 

Bill W2PKY

Down loaded HRD; Noticed I had to select reverse for the main window to decode RTTY The SuperSweeper window does not decode properly either. I'm on DIGL why do I need reverse in the main window to decode properly?

np2g

because you should be DIDU 

Bill W2PKY

Thanks, thought RTTY was LSB everywhere???? Works now!

np2g

Think DM780 is a lot easier to use and their squelch composite works .
JA's or on 20 Go get them 

Bill W2PKY

DM780 decodes much better, especially the SuperSweeper.
listening to W1AW/5 run'em..
Worked a JJ  few mornings ago. Thx for the help.
73;

Bill

np2g

OK Now for the icing on the cake 

I run DDU with the HRD apps enabled . this replaces the necessity to run HRD .
Also set the ports to switch PTT with DDUtil

This will allow you to center your frequency on the band pass I use 1500 HZS 

This way when you add filtration with the flex  the signal is optimized at this center point.
Far better copy when adding filters  to the copy.

Bill W2PKY

I will try the narrower bandpass; 
Tnx again.

Brad - N6SPM

Bill, I had a very similar problem. My USB soundcard (Signalink) worked flawlessly on digital modes (warbler, fldigi etc), but when I switched to DAX I had a poor SNR and terrible decoding. I tried everything and finally opened a trouble ticket. While awaiting Flex to contact me, I loaded SSDR on my Gaming machine and everything worked flawlessly? I cancelled the trouble ticket and gave up trying to figure out what was wrong.

Good luck

Bill W2PKY

I am using a Ethernet pigtail adapter to a USB 3.0 HUB into the USB 3.0 port on a Surface Pro 2 for my connection to the 6300.

HRD seems to work better, the SuperSweeper decodes fairly well. Good enough for now.
JT-65 and PSK are very good.

Tnx for the reply.

Bill

Andrew O'Brien

I don't recall if HRD's RTTY uses the MMTTY engine or not, but be aware that HRD is quite old.   MMTTY has had a few tweaks to its decoding methods in the past couple of years, so MMTTY's engine is probably the best RTTY decoder at the moment.   HRD is also more CPU intensive than most RTTY software, so in a situation where the user is CPU concerned, other software might be better. 
Andy K3UK

np2g

Actually the most widely used program for digi  presently is HRD .
MTTY isn't even a close last . 

Everyone can't be wrong. 

I started out with a homegrown  program for rtty on my model 19   and have had the pleasure to use just about every program  out there Including MMTTY . 

When Better  get's   here I.ll go for it.