Thank you for the detailed answer, Marcus. All crystal clear now :) Regards, Brais.
2018-03-01 20:48 GMT+01:00 Marcus Müller via USRP-users < usrp-users@lists.ettus.com>: > To expand on that: I might be overusing this figure but: > > > > If your b_sample is sufficiently smaller than the E310's maximum analog > bandwidth (to be exact, smaller than half of 56 MHz, ie. smaller than 28 > MHz, which it better be, because the storage nor network on the E310 really > isn't up to working with very high rates), you can simply use offset > tuning, indeed. > From a user's perspective, this is still baseband sampling: the offset > tuning through tune_request_t happens in the FPGA, so you're still > presented with the same samples around f_target. > > Hope that helps, > Marcus M > On Wed, 2018-02-28 at 17:28 -0500, Marcus D. Leech via USRP-users wrote: > > On 02/28/2018 03:32 PM, Brais Ares via USRP-users wrote: > > Hello, > > We are using a E310 device to capture a signal and further process it in > Matlab. We also have a frontend that lift the received signal around 43 dB > before going into the E310. > > When we use direct RF to baseband conversion we observe a high DC > suppression, around 50 dB (see figure here <https://imgur.com/a/sLWyE>) > > Is there any way to avoid it or the only option is to move this "hole" by > tuning the lo_offset in tune_request_t (then not using direct RF > conversion, but converting to IF first) further away from the signal I'm > interested in? > > And out of curiosity, which would be the exact block of the rx chain which > is performing this DC suppression? > > Regards, > Brais. > > DC offset suppression is performed inside the AD9361. > > If your signal is right at the notional centre frequency and is very > narrowband, you can get significant suppression of it. The way to deal > with this is > to use offset tuning. > > > _______________________________________________ > USRP-users mailing > listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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