Re: [Discuss-gnuradio] multiple antennas and multiple usrps

[Eric Blossom]

On Wed, Jun 25, 2008 at 02:37:48PM -0700, Dan Halperin wrote:
> Two not-that-related questions... but here goes.
> 
> 1) I notice that multi-antenna.py claims to only work with the BasicRX  
> boards. Any reason I can't use the 2 RX paths on each of 2 RFX2400s  
> assuming the d'board is powered up and configured correctly?

The RFX boards don't actually have two receive paths.  They have two
antenna ports.  The boards output analog I & Q to the usrp
motherboard, and thus two A/D's are required to handle each
daughterboard.  With a single USRP and two RFX2400s you can handle two
inputs and two outputs.

> 2) I have a transmitter USRP and a receiver USRP attached to the same  
> machine. I use usrp.serial_number() as suggested by Eric in many  
> previous mails to distinguish between them. I have a code loop like  
> this:

Are you loading a different fpga image into the different USRPs?

You can get the serial numbers without actually opening them by using
the low level usrp prims.  Take a look at usrp/host/swig/prims.i


from usrpm import usrp_prims

def get_serial_number(which):
    d = usrp_prims.usrp_find_device(which)
    if not d:
        raise RuntimeError, "Unable to find USRP #%d" % (which,)
    if usrp_prims.usrp_unconfigured_usrp_p(d):           # no firmware loaded 
yet
        usrp_prims.usrp_load_standard_bits(which, False) # load the firmware
    return usrp_prims.usrp_usrp_serial_number(d)


Eric




> which = 0
> self.u = usrp.source_c(which, <blah>)
> while self.u.serial_number() != "RX Serial":
>      del self.u
>      which += 1
>      self.u = usrp.source_c(which, <blah>)
> 
> and the analogous loop in the transmitter code. If I start the program  
> that runs USRP #1 first, then this works fine; if I start the program  
> that runs USRP #0 first, then when the other gnu radio script opens  
> USRP #0 again, finds the wrong SN, and then opens #1, the  
> functionality of USRP #0 breaks. (I think). For instance, I can't Ctrl- 
> C out of usrp_siggen.py any more if it's the transmitter running on  
> USRP #0.
> 
> Any suggestions?
> 
> Thanks,
> 
> Dan