We didn't record anything, just looked at a spectrum analyzer and saw a lot of noise in the GPS band when in USB3 mode. The radio was controlled with a small headless computer connected by a short USB3 cable (<2 meters). We put the computer and radio in a metal box sealed with metal tape so the only thing outside was the antenna at the end of a few feet of cable. Stuffing the antenna and its cable in the box with the radio eliminated the problem, confirming that the shielding was effective.
The network analyzer was connected to an antenna a few feet away, I may try using a probe to look for a hot spot. I'll probably also try replacing the antenna with a dummy load at the end of a coax to see if the radiation is coming from the cable or the antenna. On Sun, 2019-01-20 at 13:59 +0330, hossein talaiee wrote: > Could you share your EMI test results here for B210 ? > > On Sun, Jan 20, 2019 at 12:23 PM Mark-Jan Bastian via USRP-users < > usrp-users@lists.ettus.com> wrote: > > Hi Dave, > > > > You could try a shorter USB 3.0 cable, they can be as short as .2 > > meters. > > If running from a laptop, run the laptop from battery, reduces a > > radiating > > power cord and DC/DC charger/switch mode powersupplies from your > > setup. > > > > Use a second laptop with/or dedicated spectrum analyser and RF > > probes to get > > an idea of the sources and power levels, and (sub) harmonics of > > clocks > > involved in your cabling setup, and determine how to might enter > > one of > > the GNSS bands and how you are going to attenuate them. > > > > Mark-Jan > > > > On Sat, Jan 19, 2019 at 06:36:03PM +0000, d.des via USRP-users > > wrote: > > > We've experienced some GPS degradation with the B210 running USB3 > > that > > > was bad enough to kick us off a small test platform. The only way > > we've > > > found to reduce the EMI to acceptable levels was to use a USB2 > > cable to > > > force the controller down to the slower speed, and the bandwidth > > > reduction makes for a less-useful test. We did a little chamber > > testing > > > and putting the radio in a metal box didn't even help unless we > > put the > > > connected antenna in the box with it. Can anyone share experience > > or > > > ideas? I'm sorry if this has been covered on the list before, I > > follow > > > it sporadically and don't know of a good way to search the > > archives. > > > > > > Thanks, > > > > > > Dave > > > > > > > > > _______________________________________________ > > > USRP-users mailing list > > > USRP-users@lists.ettus.com > > > > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > _______________________________________________ > > USRP-users mailing list > > USRP-users@lists.ettus.com > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
