I'm working on a radar project that requires sending a series of short pulses. Looking at the pulses on a scope, I'm seeing large voltage spikes at the beginning and the end of each transmission.
As shown in the attached screenshot, before the transmission starts, there is a 90 mV spike lasting about 10 us. After the transmission, there's a -25 mV spike lasting about 20 us. The setup for this is simply a USRP B205mini-i connected to a 50 ohm input on a scope through a 30 dB attenuator. The signal is at 435 MHz with the scope sampling at 20 Gsps. Our initial thought was that we must be seeing some effects of some of the RF frontend components turning on and off. I found this previous mailing list post and tried the suggested fix in b200_impl.cpp but nothing changed: http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2015-January/012269.html Any ideas why we might be seeing these spikes or what we could do about it? Does the fix suggested in the above mailing list post still apply to the current codebase? Thanks, Thomas
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