Request for a FSK/RTTY & FAX mode option

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sat_dxer
Posts: 8
Joined: Tue Nov 02, 2021 1:20 pm

Request for a FSK/RTTY & FAX mode option

#1

Unread post by sat_dxer »

One of this things missed in version 3.2 is a mode switch for FSK/RTTY & FAX signals.
Even my old 1986 JRC NRD 525 boat anchor has a RTTY and a FAX mode option!
Having a RTTY mode would supplement using USB and a FAX mode would allow the 1.9kHz offset to display the frequency correctly in the rx window.

Thanks

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KA1GJU
Posts: 264
Joined: Tue Aug 11, 2020 2:16 pm

Re: Request for a FSK/RTTY & FAX mode option

#2

Unread post by KA1GJU »

There's a RTTY decoder in SDRC, but not WEFAX or FAX...

Ribbon Bar "View", over to the far right "More Options" and hit "Select" and chose what options you want available.
Not much room in tool bar to fit too many, so choose wisely! :D

73 Kriss KA1GJU
73 Kriss KA1GJU Home of the KA1GJU Super Station SDRC Servers in NH, USA (FN42mw & FN43na)

Max
Posts: 858
Joined: Thu Aug 13, 2020 9:47 am

Re: Request for a FSK/RTTY & FAX mode option

#3

Unread post by Max »

KA1GJU wrote: ↑Tue Nov 29, 2022 2:42 pm There's a RTTY decoder in SDRC, but not WEFAX or FAX...

Ribbon Bar "View", over to the far right "More Options" and hit "Select" and chose what options you want available.
Not much room in tool bar to fit too many, so choose wisely! :D

73 Kriss KA1GJU
Kriss, what SatDXer is asking for is that having specific mode switches changes the offset applied to the signal so that when the published WEFAX frequency is entered, it selects USB mode and applies a 1.9kHz offset to place the signal in the correct place to generate the correct audio frequency tones for FAX. So for WEFAX, for example, black tone is represented by a 1500Hz audio tone and white is a 2300Hz audio tone.

Say published WEFAX frequency is 4610 kHz, then to make this so that the tuned frequency displays the same as the published frequency, selecting a dedicated WEFAX mode would actually select USB mode but with "carrier" frequency tuned 1.9kHz lower, i.e. the equivalent "USB" mode tuned frequency (carrier) would be 4608.1 kHz, but the displayed frequency (the frequency readout) would display 4610kHz, which is dead centre of the two tones i.e. ((2300-1500)/2) + 1500 = +1900Hz.

I guess Simon could do this? Alternatively just use USB and enter 4608.1 as the frequency. I must admit I don't recall seeing that many receivers with dedicated WEFAAX mode switching? On the other hand, Simon might be happy to add it?

I guess same logic applies to a dedicated RTTY mode, but what offset? 170Hz, 425Hz, 850Hz? Bit of a minefield? SatDXer, how did the NRD515 cope with that dilemma?

Max

sat_dxer
Posts: 8
Joined: Tue Nov 02, 2021 1:20 pm

Re: Request for a FSK/RTTY & FAX mode option

#4

Unread post by sat_dxer »

Yes, Max is right the request is for "having specific mode switches" for each type of mode.

The RTTY mode switch on the NRD525 is built around a plug in module (CMH-530):
https://www.universal-radio.com/catalog ... rd535.html
The Centronics™ printer port nor the two RCA phone jacks on the back panel, were never used, but rather an external unit (with its own oscilloscope tuning aid) was used to match the mark/space width of the center frequency.
Still testing the digital decoder in SDR Console but it could also use a digital mark/space oscilloscope tuning display.

For reception of FAX center the frequency between Mark (black) 400 Hz and Space (white) 400Hz than the AF output becomes 1.9kHz is how the NRD525 switch works.

regards

Max
Posts: 858
Joined: Thu Aug 13, 2020 9:47 am

Re: Request for a FSK/RTTY & FAX mode option

#5

Unread post by Max »

sat_dxer wrote: ↑Wed Nov 30, 2022 4:15 pm Yes, Max is right the request is for "having specific mode switches" for each type of mode.

regards
Simon, this could be solved by enabling user programmable Modes so that the user can add their own mode definitions with custom offsets? Much along the lines of how the filters are now? Would that be feasible?

Max

Max
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Joined: Thu Aug 13, 2020 9:47 am

Re: Request for a FSK/RTTY & FAX mode option

#6

Unread post by Max »

Max wrote: ↑Wed Nov 30, 2022 7:18 pm Simon, this could be solved by enabling user programmable Modes so that the user can add their own mode definitions with custom offsets? Much along the lines of how the filters are now? Would that be feasible?

Max
OK sat-dxer (have you got a name by any chance?)

After my last post it occurs to me that SDRC already has exactly what you are asking for (except the actual labelling of the Mode button).

In the Modes, select "CW-U". You will then be able to program one of the filters with what you need and label it WEFAX. See the attached picture for all the filter entry number details rather than me explain it in words. Same principal applies to the RTTY offsets.

Happy WEFAX decoding!

Max
WEFAX.jpg

Max
Posts: 858
Joined: Thu Aug 13, 2020 9:47 am

Re: Request for a FSK/RTTY & FAX mode option

#7

Unread post by Max »

Max wrote: ↑Wed Nov 30, 2022 10:07 pm
In the Modes, select "CW-U". You will then be able to program one of the filters with what you need and label it WEFAX. See the attached picture for all the filter entry number details rather than me explain it in words. Same principal applies to the RTTY offsets.

Max

WEFAX.jpg
I should have said the picture also shows my suggested setup in action decoding Hamburg Meteo with the correct frequency displayed, and filter set up with 3kHz bandwidth, correctly decoding the centred WEFAX tones at 1500 Hz and 2300 Hz. I've actually been using it all day with other WEFAX transmissions. All looks good.

Simon, not sure if you are reading this thread, but it might be a nice touch to provide additional CW-L and CW-U buttons as user programmable Mode buttons that recall their own set of default (user programmable in the same way as CW-U and L), but with user definable titles. That way when (for example) WEFAX mode button is pushed it could recall the correct default filter as I have described in my last post. It's basically adding an "Add, Edit" style menu to the Mode buttons three dots menu, the same as currently exists for the Filters now.

But having said all that it's no massive deal to select CW-U and a user definable filter "WEFAX" (or RTTY) as I have shown in my last post. It's just maybe a nice cosmetic option for the Datamodes folk?

Max

sat_dxer
Posts: 8
Joined: Tue Nov 02, 2021 1:20 pm

Re: Request for a FSK/RTTY & FAX mode option

#8

Unread post by sat_dxer »

Hi Max
thanks for the tips, sri for the long delay in the reply.
On a side note is there any way to get the CTCSS feature to decode the PL codes, similar to what a police radio scanner does?

Max
Posts: 858
Joined: Thu Aug 13, 2020 9:47 am

Re: Request for a FSK/RTTY & FAX mode option

#9

Unread post by Max »

sat_dxer wrote: ↑Mon Feb 06, 2023 7:56 pm Hi Max
thanks for the tips, sri for the long delay in the reply.
On a side note is there any way to get the CTCSS feature to decode the PL codes, similar to what a police radio scanner does?
Sorry, no idea on this one. Not my area at all. One for Simon.

Max

sat_dxer
Posts: 8
Joined: Tue Nov 02, 2021 1:20 pm

Re: Request for a FSK/RTTY & FAX mode option

#10

Unread post by sat_dxer »

No problem
Would be interesting to see a SDR# type CTCSS/DSC Detector Plugin added. This would be very useful for spotting sub audio tones from distant 10m repeater locations during the current sun spot cycle.

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