[USRP-users] Using 4 USRP with a Gigabit switch
josh at ettus.com
Wed Feb 6 23:59:34 EST 2013
On 02/06/2013 03:14 PM, Damien Serant wrote:
> Hi list,
> I am experiencing some issue with my configuration using an Ethernet switch
> even if i read on the list that it should work seamlessly . Here is the
> - I use 2 pairs of USRPN200. In each pair, the 2 USRP are connected
> together with a MIMO cable, and the master USRP of each pair has the
> internal GPSDO from Ettus.
> - The master USRP of each pair is connected to a Netgear 8 port Gigabit
> - My PC is also connected to this switch.
> - I wrote a simple UHD program (based on multi_sample_to_file) to record
> the sample of each USRP. I use 1 multi_usrp object constructed with the 4
> IP address of my USRP2 (all different of course). 1 have 1 rx_stream mapped
> over my four channels so obtained.
> - I record 4 files as expected, but the program spends more than 30 seconds
> to record 5 seconds of signal as if there was some bottle-neck somewhere
> (the same without writing to the HDD). The problem is that the sampling
> frequency is 200 kHz so the Gigabit network should handle that without any
> issue, no ?
That sounds like a few MB worth of data. Shouldnt take much time at all.
Are you requesting continuous or finite streaming? I would recommend to
first count the number of samples coming out of the recv() call and make
sure its what is expected.
I guess another good approach would be to add in one device at a time
and see where the application starts getting funny / breaking assumptions.
> So my conclusion is that i am doing wrong somewhere. Actually i'm not sure
> how to handle my 4 usrp with UHD:
> - Treat each USRP pair in different USRP object ?
> - Use one multi_usrp object, but one rx_stream per pair ?
> - Execute multi_sample_to_file.exe for each pair ? -> i tried this
> solution but it does not work : the files of one of two pair remains empty.
All of those options should work. Usually ganging all 4 devices together
into one object is a just convenience for dealing w/ alignment.
> Thanks in advance
> USRP-users mailing list
> USRP-users at lists.ettus.com
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