USRP N210 growing latencies

[Fabien PELLET]

Hello,

I'm using Gnuradio 3.9 and UHD 4.1 with a N210 with only LFRX and LFTX.

I'm using USRP_source to receive samples, make some treatment in a 
flowgraph and especially a decimation, and finally send the samples to 
an USRP_Sink to get an analog signal resulting of my treatment.

My system is not perfect and a get some underrun sometimes. At each 
underrun, the propagation delay is keep growing more and more. I can 
measure that using an oscilloscope between input signal and output signal.

Why that propagation delay is always growing ?

Is there a way to reset the overall propagation delay at each underrun 
that I could catch using PMT message in a C++ application ?

Thanks for your help,

Best regards,

Fabien, F4CTZ.