Using with other programs

You may want to link the output of your SDR software with other signal processing programs.  There are at least four methods (and I would be grateful if someone who has used one or more these methods could please expand this sections).


Creating the chain


Physically link the line-out and line-in ports of your sound card


Use the Stereo Mix function of your sound card


Sigi, DG9BFC notes: Hello eddy ... if you did not tell that answer first ... I would have said similar (use stereo mix).  For any application that can use the speaker signal in parallel ... example any packet, SSTV, RTTY whatever software ... then you can use stereo mix (if your system has it available).  For any software that works between and NOT in parallel (example any audio filter software like dsp-filter from makito mori) you have to use VAC.

2 different things


Sigi notes more possibilities here (but they may require editing the registry and there is little detail).  He also notes:


Here are videos showing how to get Stereo Mix added:


Most problematic seems to be Windows Vista ... with a Sigmatel audio card ... but even that can be solved :


On some Windows Vista systems it does not work ... so make a system restore point right before you try that out ... (maybe the guy were it did not work made a fault?).


John's experience with Stereo Mix


[Note from John, who had been working with Sigi, DG9BFC]


Thank you Siegfried, at last I have found it.  Going to the speaker symbol [in the system tray] did not bring up the options you have shown in the pictures.  Instead I had to go to Control Panel, Hardware and Sound, Manage audio devices, which brings up another panel for settings.  Then I had to go to the Recording tab, which did not contain stereomix (I have did this many times before), but on

a thought I RIGHT clicked on "line in" as NO other option appeared anywhere to choose anything or change anything, the "configure" option below the panel was always grayed out and unavailable.  Then I could see the option "Show disabled devices".  After selecting it and clicking on OK button the Stereo Mix option then was shown in the panel with the other options, and I then chose Properties and enabled it. 


The panel  you showed when you click on the speaker icon does not come up in my version, it shows only a speaker and Mixer right below it.  When I click on mixer I get another panel that contains "Device" with "Speakers" below it and next "Applications" with "System sounds" below it, and no options to select anything or change anything.  It does not contain any of the many inputs yours shows. This is with the very latest of drivers available.  I have been through all these actions more times than I care to remember in the past looking for stereomix.  The only thing I did not try was RIGHT clicking on Line In in the recording panel, and why should I have?  No where is this mentioned or covered.


Thank you for your help and time! Maybe I can return it someway and sometime.


John also notes: In some windows 7 installations where the Realtek audio chipset is used it is hard to even find the Stereomix option. First go to "control panel", then select "hardware and sound", then "manage audio devices".  On the panel that comes up click on the "recording" tab at top of panel. In this panel RIGHT click on "line in". This brings up a sub-panel with various options with "show disabled devices".  Left click in front of it to select it.  Stereomix should now show in the "recording" panel.  Right click on it and select enable at the top of the sub-panel that comes up.  You will now have the Stereomix function.  This is the only way I could find the stereomix option in my system, and also for a Toshiba L675D laptop with Realtek chipset, both running the latest drivers.


But I don't have Stereo Mix available on my PC?


Colin VK5HI notes: when I came to find it on my Windows-7 machine I was disappointed that it was not present under Recording in the Control Panel => Sound dialog.  Doing a search I found that in some cases it is "hidden" by default, and if that should that be the case try the following:


Apple Mac and Boot Camp


Richard B. Langley reports: It seems that Apple does not support Stereo Mix with Boot Camp.  So, I opted to install the trial version of Virtual Audio Cable and, with Fldigi, I was successful in decoding a recorded VOA Radiogram in MFSK32/1500 Hz mode.  So I'll be ponying-up for the full version.


Use free software


There are a number of free programs which work like the VAC software listed below:



Use the Virtual Audio Cable software


There is Virtual Audio Cable software available which allows the output of one program to feed into another.  Here is a screen-shot showing HDSDR feeding MultiPSK.





Using MAP65 with Linrad for moon-bounce


Using the FUNcube Dongle PRO+ with CW Skimmer


Data Mode Reception


Sean Gilbert kindly provided this information on the Yahoo group in this message


He writes: Any sound-card digital mode decoding software can be made to work with the FCD pro+ (and whatever SDR program you wish to use) by routing the audio through a virtual sound card (VAC).  As to which one to choose, personally I have a selection of programs dependent on which mode I wish to receive.

The main ones I use are:



and these two, that have been developed for specific modes:



With the combination of the first 3, I can decode virtually anything I hear (being able to identify the mode by sight/sound is extremely useful, then you can choose the best program for the job, without spending ages going through each mode until you get a decode.  RSID helps, but only if the transmitting station includes it in their transmission, and your software can decode the RSID - which most can now).


How to identify the mode?


You may also like to check out the digital modes page on my website, as that has screen shots and sound bites from most of
the common modes, and some more obscure (all taken off air as they tend to sound a little different from tones that are generated and taken straight from the PC, rather than from the 'real world', with all the associated noises etc).  It's not complete, or definitive,  but it tends to help newcomers to get acquainted with digimodes.


73, Sean - G4UCJ


Weather Satellite Reception


These examples both use a DVB-T TV reception dongle, but should work equally well with the FUNcube Dongle, although the detailed instructions will differ.


From: Roberto Rizzardi, Italy


"Good results even if I have an old PC machine (Win XP, Pentium-4 3 GHz, 2Gb RAM, Realtek AC'97 sound-card)."  (Page in Italian, from: this SDR# group post)


From Akos Czerman, Cork, Ireland


"For about 25 Euros you can receive a weather satellite images ....."