What is the magnitude of the inconsistency? If you replace the signal generator with a 50 ohm terminator and increase the gain to near maximum, do you still see the inconsistency?
What power level are you injecting from the signal generator. Sent from my iPhone > On Apr 21, 2021, at 12:27 AM, Mike <[email protected]> wrote: > > Hello, > > I'm hoping someone can shed some light on an apparent inconsistency > issue I'm seeing with received I/Q amplitude. > > I have a B200 directly connected to an arbitrary waveform generator > through an attenuator. The generator is programmed to repeatedly send a > fixed sequence of AM pulses at a set power level. On the host (Ubuntu > 20.04, UHD 3.15.0), a C++ program simply gathers samples (48 MSPS, sc8 > OTW and CPU) and computes the average amplitude as I^2 + Q^2. > > During a run of the host software, the reported amplitudes are > consistent from sequence to sequence. > > However, if the host software is stopped and immediately restarted, > without changing the generator, the reported amplitudes are again > consistent but at a different level than the previous invocation. > > Is there some internal adjustment or variable setting performed during > USRP creation and setup that would cause the received I/Q sample > amplitudes to vary with each startup? > > > Thanks! > > >
