[hpsdr] VAC, RX2, and application integration

[John Ackermann N8UR]

In getting ready for the CQ VHF contest last weekend (which was a total 
propagation bust up here in far northern Michigan), I've been trying to 
integrate PowerSDR and Hermes with several logging and other 
applications.  The good news is that with DDUtil I've been able to get 
all the serial port related stuff working without too much trouble.

However, using VAC for, e.g., sending voice CQs via Writelog, has been a 
real challenge.  I ultimately was able to get minimal voice file 
playback working, but nothing like the full audio integration Writelog 
is capable of.

Now, I'm messing with CW Skimmer on the theory that it will be helpful 
to monitor the 6M beacon subband.  What I want to do is send raw I/Q to 
CW Skimmer via VAC.  I have gotten things sort of working, but have some 
questions for which I've not found clear answers in the documentation. 
Any help will be hopefully repaid when I document all this integration 
stuff for posterity.

I *think* my goal, for maximum Skimmer usability, is to use RX2, tuned 
to the 6M beacon segment, to output I/Q samples to the Skimmer via one 
of the VAC cables.

1.  What signals can VAC2 handle?

	a.  Is it limited only to RX2?
	b.  Will it send RX2 I/Q data?  (I assume so because of the "Direct 
I/Q" tick box, but haven't successfully done it yet.)

2.  When selecting "Direct I/Q Output to VAC" under either VAC1 or VAC2:

	a.  Does the selected VAC sample rate matter (vs. the radio sample rate)?
	b.  Does the "Stereo" box need to be ticked (or unticked) for I/Q samples?
	c.  Does the VAC RX gain setting have any effect on the I/Q magnitude?
	d.  Are there any other settings that are important to sending I/Q samples?

3.  If I only want to use one Line of a VAC pair, can I disable the 
other line?  (I think I am finding some situations where a feedback loop 
is created between the two lines.)

4.  Is RX2 limited to 48 kHz bandwidth?  That's what I seem to see, 
though I have the HPSDR sample rate set to 96 ksamples.

5.  Is there any reason I would want to select the "Microsoft Sound 
Mapper" input or output when setting up the VAC cables?  What would be 
the result of doing so?

6.  Finally, has anyone gotten PowerSDR/Hermes fully integrated with CW 
Skimmer in this way?

(I know there is an ethernet interface from Hermes directly to CW 
Skimmer, but I believe that setup "hogs" the radio so you can't run the 
skimmer and PowerSDR at the same time.  It's great to feed the Reverse 
Beacon Network, but I want the skimmer to be a second set of eyes while 
the radio operates normally.)

Thanks!

John