What does the signal look like in the time domain? Is it driving the amplifier on the B205mini into saturation?
Brian On Wed, May 8, 2019 at 7:57 PM Michael Deacon <micha...@sysware.com> wrote: > I added some attenuation. The overload is gone but the condition persists. > > > > Thanks, > > > > Mike > > > > *From:* Brian Padalino <bpadal...@gmail.com> > *Sent:* Wednesday, May 8, 2019 4:37 PM > *To:* Michael Deacon <micha...@sysware.com> > *Cc:* usrp-users@lists.ettus.com > *Subject:* Re: [USRP-users] Relationship between IQ values, gain and > noise on B205mini transmitter > > > > On Wed, May 8, 2019 at 7:28 PM Michael Deacon via USRP-users < > usrp-users@lists.ettus.com> wrote: > > Hello, > > > > I have a simple transmitter consisting of a file source connected to a > USRP sink (attached image radio.png). The file contains interleaved > floating point IQ representing a few seconds of LTE. The IQ amplitude > values are normalized between +1.0 and -1.0. The sink is configured to > 60db, 7.5MHz sample rate, 385MHz center frequency and 5MHz bandwidth. The > output looks exactly like the original on a spectrum analyzer (see attached > good.jpg). If I turn up the gain on the sink or increase the amplitude of > the IQ data I get what looks to be noise on either side of the signal > spectrum (see attached bad.jpg). Any idea what is going on here? > > > > Your bad.jpg picture has the spectrum analyzer saying OLVD. Try changing > your reference level of the spectrum analyzer to be higher so you don't > saturate the input of the spectrum analyzer. > > > > Tell us if that fixes it for you. > > > > Brian >
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