[Discuss-gnuradio] UHD vs. USRP2 driver questions

[Kevin Tien]

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?

2) As far as we can tell through searching the Internet, the sampling
rate in the Tx/Rx blocks has replaced the decimation and interpolation
fields from the legacy blocks. But what exactly are we specifying with
the sampling rate now? Is it the sampling rate the rate at which the
transmitter transmits samples, with interpolation assumed if the data
going into the block isn't throttled? In which case, would higher
sampling rate imply lower 'interpolation' rate? Bottom line, we have
no idea how to play around with the sample rate, or how important it
is.

Thanks for your help,
Kevin Tien