[USRP-users] TwinRX RX1 LO1 occasionally at wrong frequency

Neunteufel, Daniel daniel.neunteufel at tuwien.ac.at
Thu Nov 7 13:51:07 EST 2019

Hi all,

I'm using two X310, each with two TwinRX daughterboards, connected to a host via two 10Gbit SFP+ links per X310. The host machine runs UHD using DPDK on ubuntu 18.04.

When applying a CW (2.44 GHz) signal at the input of all 8 ports and running rx_samples_to_file for all channels, occasionally, the obtained IQ data does not contain the applied signal. This happens randomly, in about 50 % of the cases, only on the TwinRX RX1 channels and only on three out of four TwinRX daughterboards.

I tried to debug the problem and it turns out that in those cases the LO1 of the affected channels cannot be observed at 3.69 GHz as expected, but rather around 3.25 GHz.
The UHD API, however, claims that everything is in best order when reading back the LO values. Inserting delays after setting the frequency values as recommended does not help, either.
All LO sources are set to "internal".

Any ideas what could be the issue here? Thanks!


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