Tuesday, November 29, 2011

Re: [Discuss-gnuradio] UHD vs. USRP2 driver questions

On 11/29/2011 03:37 PM, Josh Blum wrote:
>
>
> On 11/29/2011 02:38 PM, Kevin Tien wrote:
>> Hi,
>>
>> We're using USRP2s with the RFX2400 daughterboards, and we've recently
>> switched from the old USRP drivers to the UHD drivers as per general
>> recommendation. However, we've run into a few problems that have us
>> stumped:
>>
>> 1) Previously, our receiver gains were set to 0 dB and we had no
>> problem receiving a signal with>30 or 40 dB SNR. However, now the UHD
>> receiver blocks need specified gain around 30 or 40 dB to achieve this
>> same performance; did baseline values change?
>>
>
> Are you selecting the correct antenna? Its possible the default RX
> antenna setting is different.
>

Yes, I believe the default under the old usrp drivers was "TX/RX". The
default under the new setup is "RX2". You can make a call
usrp->set_rx_antenna("TX/RX"). That should, in theory, restore the old
behavior (although I've seen what might be unpredictable behavior in
this mode - I don't know for sure though) unless you have some full
duplex shenanigans going on. Alternatively, you can just screw on an
antenna on the RX2 port and you should see a strong signal, which is the
approach I often use.

Arun

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