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Author Topic: RTTY settings?  (Read 4199 times)
WA7KPK
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Posts: 129




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« on: May 12, 2012, 07:04:18 PM »

I hate to sound like a dolt . . . but in this case I pretty much am.

I'm trying to listen to the hams piling up to work 7O6T on 20m and I can't get an intelligible RTTY signal out of any of them, even the loudest and brightest on the fldigi waterfall. What settings do I need on my receiver (an FT-857, if that matters) and my software (fldigi) to get these signals to decode? I think I've tried every single combination of "DIG MODE" (menu #38 - PSK-U, RTTY-L, etc.) and RTTY mode (RTTY 45.45/170, RTTY 50/170, etc) with no luck.

Thanks.

73, Creede
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VA7CPC
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Posts: 2403




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« Reply #1 on: May 12, 2012, 10:46:23 PM »

If you can hear the signals, and see them on the waterfall, fldigi should be able to decode them.  The "mode" options affect transmission, but fldigi is just decoding audio -- you could receive RTTY with the rig in "CW" mode and get good copy.

They're almost certainly RTTY-45  (45 baud, 170 Hz shift, Baudot coding).

However, you may be listening in the wrong sideband.  That reverses "mark" and "space", and makes everything decoded into nonsense.

Either shift the rig from USB to LSB (and change the carrier frequency appropriately if necessary), or:

. . . use the "Rv" button on fldigi's display (toward the lower right-hand corner)
. . . to shift fldigi's decoding algorithm from "mark high" to "mark low".

I'm assuming that the "Rv" button does that -- I haven't checked the documentation.  but every other RTTY decoder has than option, usually labelled "REV".

         Charles
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WA7KPK
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Posts: 129




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« Reply #2 on: May 13, 2012, 04:00:15 PM »

Thanks Charles. Yeah, I would think decoding would be automatic, but for some reason I'm getting nothing but gibberish. If it was a string like KPK KPK KPK I could guess people were just sending their suffixes, and the transmissions are short enough that I suspect some people are. But that's not what I'm seeing - it's all just random strings.

I think maybe I need to hunt down a solid source of copy like the ARRL RTTY bulletins and make sure I can copy that before I move on to weaker signals. Thanks again.
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HS0ZJU
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Posts: 163




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« Reply #3 on: May 14, 2012, 04:40:48 AM »

Not sure what radio you have but for testing receive try using fsk if you have it....this should take some variables away...
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W5DQ
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Posts: 1209


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« Reply #4 on: May 14, 2012, 10:08:42 AM »

Not sure what radio you have but for testing receive try using fsk if you have it....this should take some variables away...

Problem with FSK mode is it usually comes out of a different port on the radio than AFSK does or at least on different pins if same port. FSK also requires a bit more interfacing than a standard generic audio soundcard interfacing.

Sounds like he is on the wrong sideband or needs to select (or unselect) REVerse, which ever is appropriate. I did notice that this weekend while listening to the 7O6T RTTY pileups, I noticed that the signals were so piled on top of one another, my setup, which is usually a smooth copy on 95+% signals, was having issues and getting alot more jibberish than expected so that may have contributed to his issues.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
HS0ZJU
Member

Posts: 163




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« Reply #5 on: May 14, 2012, 10:58:40 AM »

Not sure what radio you have but for testing receive try using fsk if you have it....this should take some variables away...

Problem with FSK mode is it usually comes out of a different port on the radio than AFSK does or at least on different pins if same port. FSK also requires a bit more interfacing than a standard generic audio soundcard interfacing.

Sounds like he is on the wrong sideband or needs to select (or unselect) REVerse, which ever is appropriate. I did notice that this weekend while listening to the 7O6T RTTY pileups, I noticed that the signals were so piled on top of one another, my setup, which is usually a smooth copy on 95+% signals, was having issues and getting alot more jibberish than expected so that may have contributed to his issues.

Gene W5DQ

If he just uses it to test his receive not tx the settings should be the same...
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W5DQ
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Posts: 1209


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« Reply #6 on: May 14, 2012, 11:12:38 AM »

Not sure what radio you have but for testing receive try using fsk if you have it....this should take some variables away...

Problem with FSK mode is it usually comes out of a different port on the radio than AFSK does or at least on different pins if same port. FSK also requires a bit more interfacing than a standard generic audio soundcard interfacing.

Sounds like he is on the wrong sideband or needs to select (or unselect) REVerse, which ever is appropriate. I did notice that this weekend while listening to the 7O6T RTTY pileups, I noticed that the signals were so piled on top of one another, my setup, which is usually a smooth copy on 95+% signals, was having issues and getting alot more jibberish than expected so that may have contributed to his issues.

Gene W5DQ

If he just uses it to test his receive not tx the settings should be the same...

You may be right for some as I haven't alot of experience on all rigs but I know on my setup using a soundcard input, when I select the FSK mode vice the SSB mode, I get nothing on the software display as the FSK inputs are on a different set of jacks (which as empty and unused) from the 13 pin ACCY2 input on the back of my TS-940S. Maybe on the newer rigs it is all in one jack/plug lash up but on most older gear I have dealt with, they have seperate FSK IN/OUT jacks.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
AA4PB
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Posts: 12980




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« Reply #7 on: May 14, 2012, 11:47:46 AM »

A massive pile up is not the place to be trying to sort out your RTTY setup  Cheesy Too many possible variables.
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WA7KPK
Member

Posts: 129




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« Reply #8 on: May 16, 2012, 11:25:20 AM »

A massive pile up is not the place to be trying to sort out your RTTY setup  Cheesy Too many possible variables.


Agreed, which is why I mentioned the bit about the RTTY transmissions from W1AW.

But! I did get RTTY sorted out, or as much as I'm likely to. The issue, as VA7CPC suggested, was that I needed to hit the "RV" button.

And yeah, I figured it out in the middle of a pileup of people looking for both Yemen and the Somali operation. Lots of signals to test on in there. I parked on top of the strongest signal in the pileup, hit RV and his call came right up. I hope he worked both of 'em.  Grin
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