Beginning in RTTY

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Hello everyone.
This morning I was listening FT4JA in RTTY mode and I was delighted with the pile up.
I opened the FLdigi, RTTY in the Flex 6300 and started decoding...disappointing
I am a PSK operator, then realized I did not know anything about RTTY.
Someone would have a tutorial on how to configure the SmartSDR and software (FLDigi maybe) to receive and transmit RTTY properly?
Remember, I never used RTTY mode.
Sorry if the subject has been much discussed or if it is ridiculous to many, but I am a happy learner.
Thank you all.
Claudio - PY2PP
Brazil - SA
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Claudio - PY2PP

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Posted 2 years ago

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Bill Turner

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Hi Claudio and welcome to RTTY. I would suggest two sources for more info on RTTY:  1. Don, AA5AU has an excellent website at http://www.rttycontesting.com/rtty/ Much of his website is oriented to contesting but much is for casual RTTY ops too.  2. Please join the RTTY Reflector at contesting.com:  http://lists.contesting.com/mailman/listinfo/RTTY  This group is one of the oldest ham radio groups on the internet with more than 1000 members and you will find lots of help there.


73, Bill W6WRT

RTTY List Administrator at contesting.com


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Larry Loen WO7R

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Running RTTY as a mode is relatively straightforward.  I'm sure there's good tutorials. If the split stays within about 3 KHz, or is simplex, it's no particular problem.

Running RTTY pileups with wide splits is a big problem.  I have asked for a real VFO emulation, but so far, no dice.  So, the typical tricks other rigs use (and the software tacitly expects) such as swap A and B or a "momentary" switch from one slice to the other just isn't there.

Because of that, the only way I have found to reliably run wide splits in RTTY is to involve two slices and have two different software programs running in each slice.  In more recent versions, the SmartSDR software really wants the transmit to be in Slice A, so configure acordingly.
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Walt

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Last time I used FLDigi in RTTY - it was all reversed.  In other words, you had to use an USB mode on your radio, or operate FLDigi in reverse mode to get any decoding.

I suggest a good starter would be the software MMTTY.  It is an old standby and is used a lot in contests.  There is lots written on how to configure it with default tones and FLEX RTTY mode has those tones ready to go.  (you can change those tones in the DSP button, in the Freq. window on the panadapter - but start off with the default standards until you are ready for more)

And remember FLEX is an AFSK transmitter only - no direct FSK keying. (will stay off soapbox about that)

Cheers and have a pint or two for your hard work when you do a good decode.
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Ken - NM9P, Elmer

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@Guy and Walt, I still prefer MMTTY for RTTY. It is just simpler that most of the others. For me. But I use FLDigi for most of my other digital stuff.

Pete, I hope to make some tutorials for RTTY and other digital modes, eventually. But the schedule of free time has been a bit thin. But they are on my list, not that most of the contests and other obligations are about over for the season.
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k3Tim

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Quick help:
the fldigi XML files are at:

https://sourceforge.net/projects/fldigi/files/xmls/flex/

To setup multiple independent slices one has to copy the files created / used by FLDIG in the users work area (not the program file area - ie. app code):

For example: copy these setup files:
"C:\Users\TIM\fldigi.files"
to:
"C:\Users\TIM\fldigi.files_VFO_B"
to use slice for A and slice B. (I prefer VFO over slice - call me old skool)
(copy paste the entire directory via ctrl-C and ctrl-V keys)
You will need to create two shortcut icons on the desktop to start fldigi in the separate directories just created:

"C:\Program Files (x86)\Fldigi-3.23.09\fldigi.exe" --config-dir "C:\Users\TIM\fldigi.files"

"C:\Program Files (x86)\Fldigi-3.23.09\fldigi.exe" --config-dir "C:\Users\TIM\fldigi.filesVFO_B"

Obviously I'm running version 3.23.09 at this station. When new updates for the app are available I hand edit the shortcut to match.

The interested stugent will be able to make additional instances should it be required.

Using RTTY mode in the 6x00 is a big plus.  I change the mark frequency from 2125 to 1000. This makes the 'carrier' only 1 kc higher than the actual "tones".
In the fldigi, configuration - MISC - Sweetspot one has to set this to be at the center of the "audio tones". In my case it is (1000 + 1170) / 2 = 1085. The diligent stugent can easily derive their setting. 
On the 6x00  "PHNE" sub panel  make sure the high and low cut frequencies will pass the RTTY audio tones. It seems one can make these "tight" to match the audio tone pairs but I do not believe there is any advantage to this. Anyone know the answer?

I believe FLDIGI does use shaping of the transmit AFSK signal, which is important to a clean Xmit signal. Some of the aforementioned websites go into length about this. 

IF FRS were to implement FSK, they would have to perform wave shaping and not a simple FSK (even if it were phase coherent),  At least that is how I read the RTTY writeups.

AFSK on the 6x00 is a bit of a misnomer if you ask me. AFSK implies the audio signal is floating around in analog as in the old days of RTTY. This is not the case but the audio is pure digital going into the 6x00 and stays in the digital domain until it hits that antenna connector. From a mathematically / signal processing wise I can see no advantage of FSK over AFSK. The proper term for AFSK in this case should be baseband FSK. 

3k splits -   I tried a 10,000 split using same slice / RTTY and it works fine. I believe there was a s/w revision that allowed splits to be > 3kc. (again, the interested stugent would study the release notes to verify)

Begards,

_..--
k3TiM
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Guy G4DWV/4X1LT

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Tim, when the RTTY mode first came out, the sweet spot grew for FLDigi was 2210 or something very close to that. Cannot check that at the moment as not at home. Thank for your post. It is still not 100% clear what the Flex RTTY mode brings to the table...it's a way of getting the "correct" freq AAUI. I was told that using a narrow bandwidth in FLDigi was bad for performance.
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k3Tim

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Hi Guy,

You are correct, 2210 is normal sweetspot (2125 + 2295) / 2  using standard tones and 170 shift.

Narrow B/W.  I believe using to narrow a b/w will hurt demodulator, especially if it uses a matched filter or similar algorithm.  In the paper "The Essentials of RTTY Contesting" (slide 40) the author says to turn off the twin-peak filters.

RTTY Mode: While I did not observe an improvement in RTTY mod/demod using this mode, the panafall and tuning are more intuitive in RTTY mode over the previous DIGU.  This is especially true for split mode. If one doesn't see step up in RTTY mode over digu, I take that to mean the user understood the mapping of RTTY onto digu well. 

Best,
K3TiM
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Tim - W4TME, Customer Experience Manager

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Spots also work correctly because the MARK frequency is the Slice "dial" frequency.
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Guy G4DWV/4X1LT

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With all due respect. I would avoid using MMTTY for a noob, as I am. I would advise using FLDigi as it covers many digi modes with only one program to use. Support is excellent, documentation brilliant and active Yahoo group.

To use MMTTY, I'd advise using it with WinWarbler. Part of the DXLabs suit with excellent support via the Yahoo group and possibly the best documentation on the planet. 2Tone can also be used at the same time as MMTTY is very scary to a noob if used without hiding the UI.

Sorry if post does not make much sense. Being written post op.
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Claudio - PY2PP

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Thanks to all the information.
Bill - W6WRT, I read all the tutorial carefully and try to learn something.
Thank you.
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Walt

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Makes sense to me, Guy - another good prospective.  I use 2tone a bit too.

And get well soon - like seeing your posts in here,

Cheers
 
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Guy G4DWV/4X1LT

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Walt, mni tnx for ur kind words. Cheers, Guy.
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k3Tim

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Guy -

Get well fast my friend...

Tim
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Guy G4DWV/4X1LT

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Mni tnx fer that, Tim
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Claudio - PY2PP

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First station worked... 5V7D with FLDigi. \o/

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