Hello! I have been doing a simple test where an impulse (with a rather small duty cycle) is sent over a (short) wire and then captured by two N32x boards synchronized with White Rabbit. The B210 has a sampling rate of 4 Msps, while I’ve tried using both 10 Msps and 5 Msps for the N32x (with the bandwidths adjusted correspondingly).
To my surprise, the amplitudes of the signals seem to be “modulated” — see, for instance, a plot of the absolute value of the signals here: https://ibb.co/PggyT06 This effect “magically” disappears if I configure the two boards to have a coherent frontend — by connecting “out0” of the N321 board to the LO input on the N320, and “out1” to “in1”, where I do the latter despite using only the first channel of each board. Even weirder, if I just configure the N321 board to use the coherent frontend (thus being a timing source and destination), while I leave the N320 as it is, the signal on the N321 is just fine while the other gets largely distorted: https://ibb.co/Q9qqKcq My guess is that I’ve misconfigured something…. but what?\ The only differences are the commands: `usrp->set_rx_lo_source("external", "lo1", 0);`\ `usrp->set_rx_lo_source("external", "lo1", 1);`\ `usrp->set_rx_lo_export_enabled(true, "lo1", 0);`\ `usrp->get_device()->get_tree()->access<bool>("/blocks/0/Radio#0/dboard/rx_frontends/0/los/lo1/lo_distribution/LO_OUT_0/export").set(true);`\ `usrp->get_device()->get_tree()->access<bool>("/blocks/0/Radio#0/dboard/rx_frontends/0/los/lo1/lo_distribution/LO_OUT_1/export").set(true);` on the N321, with just the first two lines for the N320 — but I cannot see how this could affect the acquired signals… Thanks a lot in advance for any help! Best,\ Rob (note: I’ve also asked help on this on dsp-related, thinking this was an issue with my understanding of SDRs, but the last test mentioned above made me wonder whether this was an issue due to a misconfiguration of the N32x boards…)
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