RTTY Shift DXLog

DL7JAN

Hello,

during the CQWW RTTY contest I experienced the following problem in DXLog in combination with MMTTY...

The spots in the bandmap were all 2.1khz down to the QRG in SmartSDR. So you never could jump or click to the correct QRG.

Example:

W1ABC transmit on 14106.9 which is correct QRG and after clicking bandmap the radio jumps to 14.109

Does someone know the solution to fix it??

73 Jan,DL7JAN

Mike-VA3MW

RTTY signals are actually 2125hz away from the VFO carrier frequency as you saw.

The RTTY Mark is an IF shift of the Slice Receiver indicated frequency which allows click tuning and spot frequency reporting to third-party programs that expect the reported frequency to be the RTTY Mark frequency.

There are settings that impact this. What mode were using on the Radio? RTTY or a Digi mode?

Have a look at section 36.5 in the SmartSDR V3 manual that describes the key parts of the RTTY setup.

If you were using N1MM, then it sound like you do not have it configured correctly, so have a look at their documentation regarding the RTTY offset.

It gets worse as you don't know if the person spotting on a cluster is reporting the VFO reading or the RTTY Mark frequency.

KD0RC

This problem has been with us for a very long time... I wrote an article for QST that was published in the June 1992 edition as a Hints and Kinks piece on page 63. If you are an ARRL member, you can go to the QST archives and take a look. Hopefully, it will lend some clarity to using RTTY frequencies.

The bottom line is that a RTTY frequency can be expressed as the SSB suppressed carrier frequency, or as the Mark frequency, or even as channel center frequency (half way between Mark and Space frequencies). Extra confusion happens if you use LSB vs USB as the Mark and Space would need to be swapped.

As Mike noted above, two stations can be on the same Mark frequency with different frequencies showing on the radio (or conversely, show the same frequency on the radio, and yet be off by the Mark frequency).

I haven't played with RTTY in quite a while, but all this discussion has me interested to see how it works with my 6400...

KD0RC

Was able to get MTTY working right away. I did notice that I need VOX on to transmit, but then the mic picks up ambient audio and transmits it. To solve that, I selected ACC (which has nothing connected) and the problem went away without having to unplug the mic. Is there another setting somewhere that takes care of this?

It looks like the Flex properly reports Mark frequency.

I heard a very weak CE6 on 20, but by the time I got my antenna turned, he was gone. Guess I will have to listen around and see what I can do!

Mike-VA3MW

Hi Len

You should not need VOX in RTTY mode. You can setup N1MM to send CAT PTT commands for digital modes. If the Mic was live, then it sounds like you were not using TX DAX as that is the audio path into the radio.

Mike

KD0RC

Hi Mike, I'm not using N1MM, I'm using MTTY. I did get it all figured out... I found the CAT setup in MTTY and got that working (wasn't obvious where to set that...). That gave me CAT control of PTT which let me turn off VOX. With VOX off, the mic is no longer part of the equation. I also use the RTTYDefault mic profile with RTTY which turns off the mic bias. That way, if I accidentally have VOX on, there will be no audio from the mic.

If DAX is on and VOX is on, ambient noise is still picked up by the mic (and it can key the rig), so that might be something to look into. It appears that when DAX is getting audio from MTTY, no ambient audio makes it to the rig from the mic. If MTTY is in RX, then the audio can trigger the VOX if it is on. Let me know if you can't recreate this, and I would be happy to do a TeamViewer session to show you what I see.

DL7JAN

Hello,

got the solution within the setup in DXLog...

In DXLog you have to do the following:

Options – Interface specific Options – Use Decoder freq correction

„Use Decoder freq correction“ has to be UNCHECKED

…and than the Flexradio follows the correct QRG as shown in the bandmap :-)

73 Jan,DL7JAN

Mike-VA3MW

I believe the DAX / VOX issue is a known bug.

KD0RC

Ah, OK - Thanks Mike. It has easy workarounds, so not the worst thing...

All this discussion has me back into digital modes again. I am not a fan of FT8 (yes, I have tried it...), but had a great QSO with NU4N on PSK31 using 25 Watts. I had no cabling issues, no ground loops no hassle whatsoever! All this because there are no audio cables thanks to DAX. In the old days, I ran a lot of AMTOR and PACTOR on HF. Every time I moved something or plugged/unplugged something, I managed to get a ground loop or RFI.

Mike-VA3MW

I agree Len

I keep trying to grab some RTTY QSO's as well. Just keep calling CQ.

73