[USRP-users] Using 4 USRP with a Gigabit switch

Damien Serant damien.serant at gmail.com
Wed Feb 6 16:14:23 EST 2013


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
situation:
 - 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
switch.
 - 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 ?

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.

Thanks in advance
Damien
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