Re: USRP X410 Underflows and Overflows

[Marcus Müller]

Hi Olivia,

generally, Python blocks for signal processing are pretty limited in speed; so I'd really 
recommend you compare your code's performance with Signal Source (sawtooth) -> frequency 
modulator or Signal Source (sawtooth) -> multiply with itself (giving you the square) -> 
phase modulator (maybe you remember Lars Gölz's chirp modulation Bachelor Thesis: that's 
what he did!).

Other than that, you're sadly not sharing the code of your chirp generation, nor the flow 
graph, but only partial screenshots of text – that's not very helpful to help you!

Best,
Marcus

On 14.02.24 12:48, Mammadova, Olivia wrote:
> Hello together,
>
> i wrote a code for a linear chirp and added the code to the python generated by grc, 
> because GNU Radio has no building block for a linear chirp  except using Signal source and 
> VCO Block.
>
> I tried to simulate the linear chirp signal on USRP X410 and send  the chirp signa to USRP 
> X410 l and check the output with the spectrum analyzer. Unfortunately, the simulation 
> causes underflows and overflows for  the sample rate starting at 1 MHz and i cannot 
> receive a proper linear chirp at UHD Source. Moreover, the CPU Usage during the python 
> simulation is below 10%..  When i stop the simulation and want to restart the simulation, 
> RFoncError occurs: Attempting to reconnect input port.
>
> I tried to resize the buffer using sudo nano /etc/sysctl.d/99-custom.conf and added 
> net.core.rmem_max=250000000 and applied the changes using sudo sysctl -p 
> /etc/sysctl.d/99-custom.conf.  The the buffer size is resized, but the overflows and 
> underflows are yet occuring and the cpu usage is below 10%.
>
> I am sending you the screenshots of my simulation console and hope that you 
> help me!
>
> Thank you in advance!
>
> Best regards,
>
> Olivia Mammadova