HPSDR Diversity

[WA1GFZ]

I just got my HPSDR with dual RX boards up and running with ethernet interface.
I put one RX on the 80 meter dipole and the other on the 160 meter antenna.
I was listening to the guys on 3880 and could null Bob KBW to under S9, and he was strapping. This will be fun once I put up some low noise RX antennas later this summer. the newest version of Power SDR  allows me to run this stuff at full bore. The interface is only 100T but hardware will go 1000T at some point.
It has been a few late nights getting this thing going with the help of some smart hPSDR guys.

[W1VD]

Cool stuff Frank. Anyone working on diversity transmit?

[W3GMS]

Hi Frank,

That could come in handy when you don't want to hear someone that is 10 KC off your listening frequency  .

Joe, W3GMS

[WA1GFZ]

Joe the single RX set up will allow you to listen to another QSO within the pass band of the spectrum display. I do it all the time.
It was funny to listen to Blaine on 3880 talking about wanting an SDR rig with Ethernet interface as I look at my working system that will do 1000T at some point.

[K1JJ]

I was listening to the guys on 3880 and could null Bob KBW to under S9, and he was strapping. This will be fun once I put up some low noise RX antennas later this summer.

Pretty impressive.

Now that we have T-storms around, try it while listening to Europe on 75M. Can you find any nulls on the T-storm static?  I had poor results with T-storm nulling using analog methods as well as others using digital nulling like you're doing.

Having one antenna with a different polarization (dipole/vertical) might give the edge needed to null the higher angle T-storms that may appear a few hundred miles to the west.  Now that wud be cool and worthwhile. Even 5-10db nulls would be worthwhile. The active auto-nulling method might be the only way, since T-storm prop is so widespread and ever-changing in vertical or horizontal angles. (As well as strikinging in random places - too fast to give the system a chance to work.)

However, standard integrated "hissing" atmospheric static that can be nulled with a standard Yagi would work FB with your system too. There are nights when the general accumulated noise from the west can be dropped down 15-20db by beaming northeast to Eu. Those are the nights that the dipole guys are deaf and the directive array guys with the 4-squares or Yagis are working the pileups.

Usually, when working DX there is no ham QRM 95% of the time - so atmospheric static /T-storm nulling wud be an edge if it can be accomplished.

T

[WA1GFZ]

Tom,
I plan to bring both 40 meter loops into the shack and do phasing in the shack with a half wave run of coax is series with both 75 ohm stubs. This way I can connect both loops to the receivers. I plan to do this soon to see how well the phasing works. Also planning to put low noise loops back up later.

[K1JJ]

Think about introducing vertical polarization too. Maybe the sharp high angle vertical null of a vertical will help to drop out some high angle T-storm static at times when the T-storms are still to the west and you're listening NE for Eu. Or, when they are to the NE and you want to hear west for AM. Worth a try.

[WA1GFZ]

Tom,
I went up the tower and added another feedline to the loops. Now I have 50 feet of LMR400 hanging off each RG11 stub so I'll have to retune but can interface to both mercury boards. I have not made the 122 MHz clock modification to get best performance but was able to null WTIC pretty well I think it was 20 to 30 dB. I also looked at some EU BC stations above 40M.
Then WWV on 15. It is pretty easy to get 10 to 15 dB of null but you have to tune carefully to go higher. Changing conditions effect the null depth. I suspect changing angles and QSB. I want to put up some low noise RX antennas next.
BTW Joe told me there was a problem with ozy software and it is fixed. That is the reason it would not work. I guess I'm the first guy to try to use it. he also modified his set up instructions to make them clearer.