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kit-cel / gr-radar

GNU Radio Radar Toolbox
GNU General Public License v3.0
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Change the frequency while the echotimer is running #33

Closed IMchanging closed 3 years ago

IMchanging commented 5 years ago

I want to change the frequency to implement a step-freq radar by Echotimer. I have modified some codes in echotimer to make the center-TX/RX-frequency alternative. And the baseband signal I used is CW.But here‘s the problem,the phases of each frequency are not changed as my desired,even randomly.So what's the problems ?Is there something wrong about the synchronous？

dkozel commented 4 years ago

@IMchanging I'm sure this is quite late as a response, but retuning a USRP will result in a new phase offset between TX and RX. With some USRPs this offset will be the same every time for a given frequency.

IMchanging commented 4 years ago

@IMchanging I'm sure this is quite late as a response, but retuning a USRP will result in a new phase offset between TX and RX. With some USRPs this offset will be the same every time for a given frequency.

So kind of you,Thanks for your response! I have solve the phase problem by using 2 RX channals. However I found changing the center freq takes times to wait LO stable. And how can I reduce this time consumption as much as possible?

dkozel commented 4 years ago

That depends a lot on the different USRPs and daughterboards. In many cases there's not much to do, the LO takes however long to stabilize. If you are retuning at known time intervals you could modify the echotimer code to used timed commands for tuning though which removes the delay from issuing the tune command until the tune actually starts (USB/network delays, C++ scheduling, etc).

IMchanging commented 4 years ago

That depends a lot on the different USRPs and daughterboards. In many cases there's not much to do, the LO takes however long to stabilize. If you are retuning at known time intervals you could modify the echotimer code to used timed commands for tuning though which removes the delay from issuing the tune command until the tune actually starts (USB/network delays, C++ scheduling, etc).

I truly appreciate your help in resolving my problem！Thanks a lot！