devin kelly wrote:
Hello everyone,
I'm doing a project with the USRP2 that where I need to know the Time
of Arrival(TOA) of the waveforms. This is for a geolocation application.
My understanding as of now is that the hooks to get TOA are there in
the USRP2, but the firmware does not provide access to them at this
point. Is this correct?
If the firmware can provide TOA, how can I get that information??
Thanks,
Devin
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The timestamp on the frame of *samples* is indeed available - and if you
use the low-level interface to the USRP2 (libusrp2) you can see those
timestamps. However, the gr-usrp2 interface (i.e. the default source
block for working with the USRP2) does not. If you want to see the
timestamps in a GNURadio flowgraph, you'll need to create a custom block
based on the usrp2_source_[32fc or 16sc] block.
However, that won't give you the TOA of a received signal *directly*.
You'll need some scheme to decide that a signal has arrived, and then
calculate the TOA based on the timestamp corresponding to that sample
(the timestamps you get from libusrp2 are for the first signal in the
frame of samples - so you'd need to either calculate the running
timestamp for each sample, or keep track of the offset within the frame
somehow).
Good luck!
Doug
--
Douglas Geiger
Code 5545
U.S. Naval Research Laboratory
Washington, DC 20375
(202) 767-9048
douglas.gei...@nrl.navy.mil
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