Meriden ARC Web Site | Castle Craig Chapter 10-10


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FSK vs AFSK
#1
I know we don't have a bunch of RTTY radio-sport folks in the club, but those that are may find this interesting.

Back in '14 when I got my TS-2000 I built up an external interface box so I could do JT65 and other digital modes.  This box also allowed me to operate the Kenwood in true FSK mode for RTTY.  At the time I thought that was 'better' than letting my PC sound card create the tones for RTTY operation and placing the Kenwood in SSB mode.  I operated that way for a few years until the IC-7610 made it's home in my shack.  That too has  RTTY mode and when running with N1MM+ I continued to allow the radio to create the diddles of RTTY versus letting the PC sound card create those tones.  Life was good, or so I thought so.

I've been a user of Ham Radio Deluxe since getting on the air, so I've got about 10 years of use with this program.  I used the last free version until I decide to pay the HRD folks some cash about three months ago; purchasing the latest version of the software.  The interesting thing about HRD is they have FSK and AFSK mode for RTTY mode BUT FSK mode doesn't transmit decodable signals on either the Kenwood or Icom radio.  Of course, the HRD folks didn't believe me, and after opening a case with them and one of the owners finally taking over the case, they finally agreed with me (and many other users) that HRD FSK mode doesn't work with some radios.

So I continue on my way using N1MM+ for RTTY contests in the FSK mode..... until I watched and read a few videos and articles.

The first article is from the NCJ's latest issue;
   

You can read the entire article on the ARRL website if you are a member.

Next was this very informative video from YCCC.  
RTTY FSK vs AFSK

After listening to and reading these two articles and videos I'll be using AFSK in the future with MMTTY / N1MM+.

And I've been operating RTTY in USB mode forever and apparently, that's not the norm... LSB is where you need to be.  So I'll be on LSB from now on as well.  Here are a few screenshots of AFSK with MMTTY and HRD and FSK with MMTTY.  FSK, where the Icom radio sends the two tones out, has very little filtering and splatters quite a bit.  HRD in AFSK mode (PC generates two tones) is a little better.  MMTTY with the 512 tap TX filter enabled is the best at keeping splatter down and energy where it needs to be.

   

73,
Steve
KC1SA
73, Steve - KC1SA
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