[Discuss-gnuradio] Trying to figure out time of packet arrival in USRP

[Sapna Dasarath]

Hello,

I am running usrp_transmit_path.py for transmission on one USRP and usrp_receive_path.py for reception of signals on another USRP.

I want to determine the exact arrival time of a packet on the USRP.

I get the message stream which is received from packetutils.

The code in PacketUtils.py gets a packet from the USRP.

This is populated from copy_from_usrp_buffer  in usrp_source_base.cc.

I am assuming there is some polling mechanism to invoke usrp_basic_rx::read for this.

I want to track the point where this buffer is populated. The time stamp of the packet when it is detected by USRP without any modifications by higher layers. 

Can this be done without any changes in Firmware? Any pointers on how to proceed will be appreciated.

Thanks.