FSK with fldigi 4.1.20.43 - need advice #fldigi #rtty


Alex - DH2ID
 
Edited

Hi, I still can't get fldigi and FSK working on my IC-7300.
Is somebody out there, who can either tell me how to set fldigi and the 7300
to work together to produce readable FSK? Or send me his fldigi.prefs file?
Vy 73, Alex - DH2ID


Dave
 

Alex,

I am working on the fldigi / flrig FSK interface today.  Please wait for the announcement of alpha ... .44

73, David, W1HKJ

On 1/16/22 03:49, Dr.Alexander Hahn wrote:
Hi, I still can't get fldigi and FSK working on my IC-7300.
Is somebody out there, who can either tell me how to set fldigi and the 7300
to work together to produce readable FSK? Or send me his ini file?
Vy 73, Alex - DH2ID


K3EUI Barry
 

Alex and other FSK RTTY ops:

I have a question not about HOW to generate a FSK RTTY signal, but rather, WHY you want to generate a FSK signal.

In my statement above I have two questions:

1)  Why operate RTTY mode on HF these days when PSK31, THOR, MFSK, and Olivia take up less spectrum, have both upper and lower case, and copy so well with limited S/N?  I live in the Phila area, and I almost never see or hear RTTY signals on 80m or 40m unless there is a contest - and then the whole digi band is fully of RTTY.


2) I've operated RTTY by both AFSK and by FSK.  Is either method superior to the other in modern rigs?
FSK generates DATA pulses to move a VFO up/down by 170 Hz  -  so the radio itself needs to have this built in.
The data pulses must therefore be timed correctly -  22 milliseconds per tone for 45 baud.

AFSK generates the two-tone RTTY signal first in a sound card, as two distinct audio pitches separated by 170 Hz, and then injects that analog sound into the radio's mic jack or data jack.  The rig just "up-converts" the shifting audio into shifting RF -  but what comes out on the antenna is a RTTY signal. As long as the ALC is zero, I find that 25W from a 100W PEP type rig always works well, and has very low distortion. The big advantage with AFSK over FSK (for my ears) is that I can vary the pitch to anything I want, and use audio anywhere from say 500 Hz out to 2500 Hz on the FLDIGI waterfall. I usually set the radio's bandwidth to something like 500 Hz and I've never had a complaint, even when the band is crowded in a contest. On a 30 year old Kenwood  TS850 I inject the audio into the rig's MIC jack with a SignaLink sound card and adjust the power output to about 25W with more/less audio. I've never had a complaint about a wide RTTY signal.  The TS850 can also generate FSK (true) RTTY but I see no advantage to doing it that way.



I appreciate the efforts Dave and others put in to make FLDIGI more successful.

I just wonder -  what is all the fuss about operating FSK RTTY  - a 70 year old mode that does not offer the same fidelity of PSK31, THOR, Domino, MFSK and Olivia.

For our EMCOMM net in Pennsylvania (PaNBEMS net Sunday mornings 3583 kHz) we find that THOR 22 (22 baud, 78 wpm, 525 Hz bandwidth) is the best compromise mode for copy and speed, over robust NVIS paths on 80m in the mornings. THOR uses the difference in the audio pitch to determine a symbol rather than the absolute pitch itself, and will copy well even if you are 50 Hz off the sender's frequency; thus it works well even on older radios with drfting VFOs. THOR 11  takes up less bandwidth than RTTY, is much more robust, does upper and lower case, has FEC, and is just more pleasant to listen to the  multiple pitch tones (one at a time).

Just curious -  what is the push to make FSK work better on modern rigs with a Windows computer to generate the FSK data pulses?

Why the love affair with FSK RTTY?  I don't get it.



K3EUI  Barry
Philly
Jan 17, 2022


Alex - DH2ID
 

Hello Barry and thank you for your long post.
Technically you're absolutely right. RTTY (AFSK and FSK) is a very old digital mode.
It has no way to autocorrect itself and is prone to QRM and QRN.
Having said that and using a lot of other digimodes like VARA and PACTOR for
EMCOMM, I must confess that I love RTTY.
Why? Well, as a student at Heidelberg I had two RTTY machines in my kitchen.
These were the mechanical ones with a big soundproof casing which still caused
a lot of noise, smell and work. I did duplex RTTY over a repeater near Frankfurt.
I had to punch a lot of tape first, and I loved it.

AFSK is possible, but FSK is still the top mode for RTTY, if you can get your
TRX to transmit ist :-)
Yes, it's old and I am old too. But old isn't always bad. Steam engines are old,
SAQ at Grimeton is old, Morse code is old. All work very well and have a
right to exist side by side with the digimodes. 
Maybe I'm just old-fashioned...
Vy 73, Alex - DH2ID


Michael Black
 

The main advantage to FSK is you don't need an audio card, right?

But if you're already getting audio to/from the rig isn't AFSK better?  Allowing you to decode wider bandwidth and transmit wherever you want without moving the rig frequency?

Mike W9MDB




On Monday, January 17, 2022, 08:07:22 AM CST, Alex - DH2ID <dh2id@...> wrote:


Hello Barry and thank you for your long post.
Technically you're absolutely right. RTTY (AFSK and FSK) is a very old digital mode.
It has no way to autocorrect itself and is prone to QRM and QRN.
Having said that and using a lot of other digimodes like VARA and PACTOR for
EMCOMM, I must confess that I love RTTY.
Why? Well, as a student at Heidelberg I had two RTTY machines in my kitchen.
These were the mechanical ones with a big soundproof casing which still caused
a lot of noise, smell and work. I did duplex RTTY over a repeater near Frankfurt.
I had to punch a lot of tape first, and I loved it.

AFSK is possible, but FSK is still the top mode for RTTY, if you can get your
TRX to transmit ist :-)
Yes, it's old and I am old too. But old isn't always bad. Steam engines are old,
SAQ at Grimeton is old, Morse code is old. All work very well and have a
right to exist side by side with the digimodes. 
Maybe I'm just old-fashioned...
Vy 73, Alex - DH2ID


Dave
 

There are NO signal processing advantages of FSK vice AFSK.  However, if you were running a high power RTTY station then you might find that the FSK generation is less susceptible to RFI.  Most RTTY contesters want to run their equipment with maximum power.  The bigger the signal the better you can overcome the competition.  Trying to achieve maximum power using AFSK might lead one down the primrose path of distorted signals.  All of this AFSK /FSK thrashing is simply to prove that fldigi can generate the correct timing signals.  It only took me 15 years to figure out how on all of the target operating systems; Unix, Linux, OS-X, macOS, Windows(many).  FSK h/w solutions are better.  If you can afford a shiny new transceiver you surely must be able to afford the meager cost of a moRTTY interface.

73, David


On 1/17/22 08:10, Michael Black via groups.io wrote:
The main advantage to FSK is you don't need an audio card, right?

But if you're already getting audio to/from the rig isn't AFSK better?  Allowing you to decode wider bandwidth and transmit wherever you want without moving the rig frequency?

Mike W9MDB




On Monday, January 17, 2022, 08:07:22 AM CST, Alex - DH2ID <dh2id@...> wrote:


Hello Barry and thank you for your long post.
Technically you're absolutely right. RTTY (AFSK and FSK) is a very old digital mode.
It has no way to autocorrect itself and is prone to QRM and QRN.
Having said that and using a lot of other digimodes like VARA and PACTOR for
EMCOMM, I must confess that I love RTTY.
Why? Well, as a student at Heidelberg I had two RTTY machines in my kitchen.
These were the mechanical ones with a big soundproof casing which still caused
a lot of noise, smell and work. I did duplex RTTY over a repeater near Frankfurt.
I had to punch a lot of tape first, and I loved it.

AFSK is possible, but FSK is still the top mode for RTTY, if you can get your
TRX to transmit ist :-)
Yes, it's old and I am old too. But old isn't always bad. Steam engines are old,
SAQ at Grimeton is old, Morse code is old. All work very well and have a
right to exist side by side with the digimodes. 
Maybe I'm just old-fashioned...
Vy 73, Alex - DH2ID


Mike Olbrisch
 

THIS.  I want to is reason enough.  In the 4X4 community I get that all the time.  Why go through the trouble of xxxxxx.  Because that is how I want it.

 

 

Vy73  –  Mike  –  KD5KC – WRFF851 –  El Paso – Texas  –  DM61. 

 

The canyons are calling, colorful and deep.  But I have promises to keep.

And miles to go still in my Jeep...   And miles to go still in my Jeep...

 

 

ADVENTURE:  The respectful pursuit of trouble.  

An EXIT is really an ENTRANCE to someplace new. 

It isn’t an ADVENTURE until something goes wrong!

 

 

 

From: winfldigi@groups.io <winfldigi@groups.io> On Behalf Of Alex - DH2ID
Sent: Monday, January 17, 2022 7:07 AM
To: winfldigi@groups.io
Subject: Re: [winfldigi] FSK with fldigi 4.1.20.43 - need advice #rtty

 

Hello Barry and thank you for your long post.
Technically you're absolutely right. RTTY (AFSK and FSK) is a very old digital mode.
It has no way to autocorrect itself and is prone to QRM and QRN.
Having said that and using a lot of other digimodes like VARA and PACTOR for
EMCOMM, I must confess that I love RTTY.
Why? Well, as a student at Heidelberg I had two RTTY machines in my kitchen.
These were the mechanical ones with a big soundproof casing which still caused
a lot of noise, smell and work. I did duplex RTTY over a repeater near Frankfurt.
I had to punch a lot of tape first, and I loved it.

AFSK is possible, but FSK is still the top mode for RTTY, if you can get your
TRX to transmit ist :-)
Yes, it's old and I am old too. But old isn't always bad. Steam engines are old,
SAQ at Grimeton is old, Morse code is old. All work very well and have a
right to exist side by side with the digimodes. 
Maybe I'm just old-fashioned...
Vy 73, Alex - DH2ID


Joe K8MP
 

Some years ago, I worked an Aussie who was motoring across VK-Land, east to west, in a vehicle something like yours.
He was camping somewhere in the Outback at the time. Fun stuff...

Joe, K8MP

On Mon, Jan 17, 2022 at 10:14 AM, Mike Olbrisch
<mike-2020@...> wrote:

THIS.  I want to is reason enough.  In the 4X4 community I get that all the time.  Why go through the trouble of xxxxxx.  Because that is how I want it.

 

 

Vy73  –  Mike  –  KD5KC – WRFF851 –  El Paso – Texas  –  DM61. 

 

The canyons are calling, colorful and deep.  But I have promises to keep.

And miles to go still in my Jeep...   And miles to go still in my Jeep...

 

 

ADVENTURE:  The respectful pursuit of trouble.  

An EXIT is really an ENTRANCE to someplace new. 

It isn’t an ADVENTURE until something goes wrong!

 

 

 

From: winfldigi@groups.io <winfldigi@groups.io> On Behalf Of Alex - DH2ID
Sent: Monday, January 17, 2022 7:07 AM
To: winfldigi@groups.io
Subject: Re: [winfldigi] FSK with fldigi 4.1.20.43 - need advice #rtty

 

Hello Barry and thank you for your long post.
Technically you're absolutely right. RTTY (AFSK and FSK) is a very old digital mode.
It has no way to autocorrect itself and is prone to QRM and QRN.
Having said that and using a lot of other digimodes like VARA and PACTOR for
EMCOMM, I must confess that I love RTTY.
Why? Well, as a student at Heidelberg I had two RTTY machines in my kitchen.
These were the mechanical ones with a big soundproof casing which still caused
a lot of noise, smell and work. I did duplex RTTY over a repeater near Frankfurt.
I had to punch a lot of tape first, and I loved it.

AFSK is possible, but FSK is still the top mode for RTTY, if you can get your
TRX to transmit ist :-)
Yes, it's old and I am old too. But old isn't always bad. Steam engines are old,
SAQ at Grimeton is old, Morse code is old. All work very well and have a
right to exist side by side with the digimodes. 
Maybe I'm just old-fashioned...
Vy 73, Alex - DH2ID


Dave MARS Maples
 

Barry: The "direct" approach has a potential for greater spectral purity. The disadvantage is that in order to do that the transmitter has to be designed to produce the modulation desired. We aren't there yet as a general rule, and probably won't be except in some high-end situations where a digital modulator produces a direct I/Q data stream at the transmitter IF or at the carrier frequency and passes it directly to an amplifier.

The "indirect" approach (modulating an SSB transmitter with the appropriate audio tones) has the advantage that it can be done with pretty much any SSB transmitter. The issue is that unless the SSB transmitter chain is operated to preserve linearity to the greatest extent possible, the resultant transmitted signal can have more "trash" in it.

The transmitter has to have very good opposite-sideband and carrier suppression. The audio chain in the transmitter has to preserve linearity. That includes making sure that all audio frequencies get through the audio system at the same time.

The transmitter has to be OPERATED to preserve linearity. You are doing some of that by derating the transmitter power. Other hams don't necessarily understand that. Still others use an amplifier but overdrive it or otherwise distort it by not connecting the ALC connection back to the rig.

Either approach can work well, but both require some care in making sure the signal produced is free of extra artifacts.

I hope this helps a bit.

Thanks,
Dave WB4FUR

-----Original Message-----
From: winfldigi@groups.io <winfldigi@groups.io> On Behalf Of K3EUI Barry
Sent: Monday, January 17, 2022 07:41
To: winfldigi@groups.io
Subject: Re: [winfldigi] FSK with fldigi 4.1.20.43 - need advice #rtty

Alex and other FSK RTTY ops:

I have a question not about HOW to generate a FSK RTTY signal, but rather, WHY you want to generate a FSK signal.

In my statement above I have two questions:

1) Why operate RTTY mode on HF these days when PSK31, THOR, MFSK, and Olivia take up less spectrum, have both upper and lower case, and copy so well with limited S/N? I live in the Phila area, and I almost never see or hear RTTY signals on 80m or 40m unless there is a contest - and then the whole digi band is fully of RTTY.


2) I've operated RTTY by both AFSK and by FSK. Is either method superior to the other in modern rigs?
FSK generates DATA pulses to move a VFO up/down by 170 Hz - so the radio itself needs to have this built in.
The data pulses must therefore be timed correctly - 22 milliseconds per tone for 45 baud.

AFSK generates the two-tone RTTY signal first in a sound card, as two distinct audio pitches separated by 170 Hz, and then injects that analog sound into the radio's mic jack or data jack. The rig just "up-converts" the shifting audio into shifting RF - but what comes out on the antenna is a RTTY signal. As long as the ALC is zero, I find that 25W from a 100W PEP type rig always works well, and has very low distortion. The big advantage with AFSK over FSK (for my ears) is that I can vary the pitch to anything I want, and use audio anywhere from say 500 Hz out to 2500 Hz on the FLDIGI waterfall. I usually set the radio's bandwidth to something like 500 Hz and I've never had a complaint, even when the band is crowded in a contest. On a 30 year old Kenwood TS850 I inject the audio into the rig's MIC jack with a SignaLink sound card and adjust the power output to about 25W with more/less audio. I've never had a complaint about a wide RTTY signal. The TS850 can also generate FSK (true) RTTY but I see no advantage to doing it that way.



I appreciate the efforts Dave and others put in to make FLDIGI more successful.

I just wonder - what is all the fuss about operating FSK RTTY - a 70 year old mode that does not offer the same fidelity of PSK31, THOR, Domino, MFSK and Olivia.

For our EMCOMM net in Pennsylvania (PaNBEMS net Sunday mornings 3583 kHz) we find that THOR 22 (22 baud, 78 wpm, 525 Hz bandwidth) is the best compromise mode for copy and speed, over robust NVIS paths on 80m in the mornings. THOR uses the difference in the audio pitch to determine a symbol rather than the absolute pitch itself, and will copy well even if you are 50 Hz off the sender's frequency; thus it works well even on older radios with drfting VFOs. THOR 11 takes up less bandwidth than RTTY, is much more robust, does upper and lower case, has FEC, and is just more pleasant to listen to the multiple pitch tones (one at a time).

Just curious - what is the push to make FSK work better on modern rigs with a Windows computer to generate the FSK data pulses?

Why the love affair with FSK RTTY? I don't get it.



K3EUI Barry
Philly
Jan 17, 2022