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 MOn 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)
> >
> >
> >
> > 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.
>
>
>
>
>
>
>
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