[USRP-users] tunnel.py doesn't receive packages when transmit and receive frequencies are different

Josh Blum josh at ettus.com
Fri Jun 29 17:38:51 EDT 2012


> The wired thing is that when I set the frequencies of transmit and receive
> different above 2.5GHz, packages can be again transmitted and received:
> on machine A:
> *sudo ./tunnel.py --tx-freq=2.51G --rx-freq=2.512G; sudo ifconfig gr0
> 192.168.200.1 *
> on machine B:
> *sudo ./tunnel.py --tx-freq=2.512G --rx-freq=2.51G; sudo ifconfig gr0
> 192.168.200.2*
> 
> I am using USRP N210s and the daughter boards are both XCVR2450. Does
> anyone can explain why the tunnel.py doesn't receive packages when transmit
> and receive frequencies are different under 2.5GHz?
>  --


XCVR2450 has a shared LO for both RX and TX. You must make sure that the
LO is the same frequency for the RX and TX setting. Otherwise, when you
tune RX it will break the TX setting, and vice-versa.

-josh




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