USRP - underflow / overflow problem

GNU Radio
1

Hi,

I am using the USRP board with two Basic Tx boards in both the Tx slots.
I am also using both the Rx slots with Basic Tx on A side and TVRX on B
side.

I am using Tx side interpolation rate as 400 and Rx side decimation rate
as 250.

I am using a GUI with one button control to enable the Tx board and also
a scopesink to plot the received waveform. I am using NBFM Tx/Rx blocks,
filter blocks etc. I am using both the Tx and Rx parallely with each
Tx/Rx pair tuned to different frequency (100 MHz and 150Mhz)

As soon as I run the program, I get messages like

uUuUuUuUuUuUuUuUuUuUuUuUuUuOuOuUuOuUuOuOuUuUuOuUuUuOuOuOuUuUuUuUuUuUuUuUuUuUuUuU
uUuUuUuUuUuUuUuUuUuUuUuUuUuUuUuUuUuUuUuOuOuUuUuUuOuOuUuUuUuUuUuUuUuOuOuUuUuOuUuO
uOuUuUuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuUuUuUuUuUuUuOuU
uUuOuUuUuOuUuUuUuUuUuUuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuOuO.

Please let me know what goes wrong and how to get rid of this problem.

Thanks and Regards,
Sivaram

2

Narayanan, Sivaramasubramanian (R&T <Sivaramasubramanian.Narayanan
Honeywell.com> writes:

As soon as I run the program, I get messages like
Â

uUuUuUuUuUuUuUuUuUuUuUuUuUuOuOuUuOuUuOuOuUuUuOuUuUuOuOuOuUuU
Hi,

in the gnuradio docu is something written about “latency”.
Maybe this could fit up your program to solve this.
But before this you should fit up your decimation value.

Since i use the correct decimation value i doesn’t get anymore this
message.
Try to use as small bandwidth as you need. The bandwidth of the signal
used is determined by the decimation. The bandwidth of the signal
relates to the transfer speed.

But i am not 100% sure.

Regards Markus