Monday, June 8, 2015

MDSR Software IF interface ... and Asus T100...continued

(newer info at bottom)

I got a mobile device audio adapter for the Asus T100...

Mobile devices that have microphone inputs now use a single conductor jack. (common, L,R, Mic).  I got an adapter that had a 4 conductor 3.5mm jack, and the output is a pair of 3.5mm stereo plugs, one for headphone out, one for audio/mic in.  (I got mine through Amazon... search for 3.5mm 4pin splitter)

I needed that so I could use the audio for digital modes.  First some screenshots of the digital modes in use on the Asus T100, and then screenshots of settings for the audio devices.

Messy desktop with JT65-HF and MDSR running...note all the decoded contacts listed.

With Fldigi  and the MDSR-SA on the desktop...attempting to tune in some CW and have Fldigi decode.

Now the sound inputs (Recording).   With theses settings I can hear the audio with headphones plugged into the adapter, and the digital mode decoders have audio to decode.

And the Audio Output (Playback) settings.


Apparently the audio input on the Asus T100 is only mic level.   So some attenuation is needed. (I haven't added that yet)

Alex Schwarz (one of the MDSR designers) has a diagram of an mic input attenuation circuit at the MDSR Yahoo Group.

This web page also has some examples.  I will have to dig through my resistor drawer and see what I have available.

These shots are to prove the setup works, and maybe help with the settings.

I have found the audio input to the T100 is very flakey.  I don't know what criteria it uses to decide if an external mic is plugged in vs the internal mic...but I have plugged a standard mobile phone earbud/mic set and the T100 recognized the mic.  I plugged that adapter at the top in with my headset/mic which uses two plugs (that match the 2 plugs on the splitter).  The T100 kept the internal mic installed, even if I unplugged and plugged in a few times.

What that means is the audio in from the Xonar card isn't going I can't use a digital mode decoder.

In addition the MDSR software is no longer working correctly.

At this point it is a problem with the T100 and Win8.1.   If I plug the USB cord into my laptop, and plug the mic in, it all works just fine there (Win7).

So for me, I don't think I will pursue MDSR on the T100...

Part 1.

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