[hpsdr] ozy/janus as soundcard for digital modes

[Phil Harman]

Hi Stephen,


> At this point the clue I am looking for is where the problem lies, Janus
> firmware or PowerSDR code?
>

I don't think there is a problem, simply a difference. If you feed the
audio out from your TS480 into a sound card or Janus then you are faced
with the limitations of having a real as apposed to a complex signal.

With a sound card you can feed the digitised signal into various PC
programs to demodulate digital modes etc. Such programs generally expect a
real signal so all is well.

Janus *only* works with PowerSDR and expects a complex input. If you feed
it a real signal then each signal will appear twice on the bandscope and
one will tune in there reverse direction.

If you tune to one of these signals, and feed it to a suitable digital
mode program then it will demodulate correctly. The issue is that all the
signals on the band will create images and some of these *may* fall within
the bandwidth of the signal you are trying to copy.

If you feed in a complex signal, say from a SoftRock, then these images
can be substantially reduced in amplitude.

Janus is a very high performance ADC, up there with the top end sound
cards. But, without a suitable driver, its not, and was not intended to
be, a sound card.

Now... about writing a Windows driver.... :)

73 Phil...VK6APH


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