[USRP-users] N310 Images with external LO

Robert.Poehlmann at dlr.de Robert.Poehlmann at dlr.de
Wed Feb 13 11:04:27 EST 2019


Hi Kai,

I faced the same issue. Apparently it is linked to the quadrature error correction (QEC) and can be solved turning off this calibration. This can be done by setting init_cals=BASIC, where you can add the relevant calibrations but avoid RX_QEC_INIT, see https://files.ettus.com/manual/page_usrp_n3xx.html#n3xx_mg_calibrations.

Robert

From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Kai-Uwe Storek via USRP-users
Sent: Wednesday, February 13, 2019 4:53 PM
To: usrp-users at lists.ettus.com
Subject: [USRP-users] N310 Images with external LO

Hey Folks,

I'm struggling with the external LO feature of my N310. This issue might be related to http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2018-April/056233.html.

Setup:
Signal generator outputs a continuous wave at 2.002 GHz (-50dBm) to the RX2 of RF0. With internal LO everything is fine (see pic1).

Problem:
In the next step I use the device argument "rx_lo_source=external" and provide a 4 GHz CW with 3 dBm at LO IN 0/1 RX. The spectrum now shows a significant image of the input signal. I played around with level of external LO without any changes.

Any ideas?
Thanks in advance! :)

Kai

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