Jason and Marcus, thanks for your responses.  I was afraid that this was the
case.

Is there a daughterboard out there (besides the BasicRX) that can support 4
antennas on a single USRP?

The other option that would work for me is connecting antenna 0 to WBX 0 and
connecting antennas 1-3 to WBX 1 through a commutator to switch them at a
sub-1 kHz frequency.  Can you tell me if any of the unpopulated headers on
the WBX board are digital outputs that could potentially be used to generate
a switching signal and/or low rate ADC inputs that could be used to sample a
switching signal generated elsewhere?

Finally, what it would take for 2 USRPs to operate a total of 4 WBXs
coherently?  I assume this would at least require connecting Clock Out on
USRP0 to Clock In on USRP1, but is that enough to get all 4 WBX PLLs locked
together?  Also, does using two USRPs simply mean that the max USB data rate
for each USRP is halved, or is the effect more severe?

Thanks,
Scott
<[email protected]>

On Fri, Sep 10, 2010 at 3:19 PM, Jason Abele <[email protected]> wrote:

> On Fri, Sep 10, 2010 at 12:04 PM, Scott Storck <[email protected]> wrote:
> > I have a USRP and two WBX daughterboards.  Is it possible to use 4
> > independent RX antennas (all tuned to the same frequency) with this
> hardware
> > setup?
>
> Scott,
>
> The WBX has only one (I/Q) receiver per daughterboard.  The two
> Antenna ports (TX/RX and RX2) are for convenience to enable a single
> Antenna on the TX/RX in half duplex or a dedicated RX antenna on RX2.
> The WBX merely switches the input of a single RX chain between those
> two antenna ports based on user settings.
>
> So, only 2 receivers are possible with your USRP + 2 WBX setup
>
> Jason
>

On Fri, Sep 10, 2010 at 3:22 PM, Marcus D. Leech <[email protected]> wrote:

I have a USRP and two WBX daughterboards.  Is it possible to use 4
independent RX antennas (all tuned to the same frequency) with this hardware
setup?
Specifically, here's what I'm trying to achieve:
Antenna 0 -> Side A WBX, RX/TX port -> ADC0 -> DDC0I
Antenna 1 -> Side A WBX, RX2 port -> ADC1 -> DDC1I
Antenna 2 -> Side B WBX, RX/TX port -> ADC2 -> DDC2I
Antenna 3 -> Side B WBX, RX2 port -> ADC3 -> DDC3I

I am trying to modify gnuradio-examples/python/multi-antenna/multi_fft.py to
make this happen.  I've got it running, but I can't seem to get the WBXs to
use the antennas connected to their RX2 ports.

Thanks,
Scott
<[email protected]>


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 No, you will not be able to make that work.  There are *not* two
independant Rx paths within
 the WBX, only two different antenna ports, which you can switch the Rx
chain between, but there
  is only 1 Rx chain.

-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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