USRP TX/RX. Lost bytes and "U" in flowgraph execution

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pilot327
Posts: 3
Joined: Fri Apr 20, 2018 7:15 am

USRP TX/RX. Lost bytes and "U" in flowgraph execution

Post by pilot327 » Fri Apr 20, 2018 7:51 am

Hello everybody

I have the flowgraph below PIC 1 (01_01_flowgraph)
USRP transmits file (txt, picture and video) and receives this file at the same time

Transmitted video is received without some bytes and i see letters "U". PIC 1 and PIC 2 at gnuradio terminal

1. What do this letters "U" mean?
1* I think there are anothers error letters. Where can i know about it?
2. I don't know on what it (letters) depends, but when i have 3 or more "U", video  doesn't play (but despite the lack of few bytes and 3 "U" received picture is displayed normal). Why?
3. Why I lost my bytes? PIC 2 (lost_bytes)

i use gnuradio 3.7.10 and USRP1.

if you want to answer please do it considering i new in gnuradio and usrp
Attachments
01_01_flowgraph.png
PIC 1
01_01_flowgraph.png (469.14 KiB) Viewed 460 times
lost_bytes.png
PIC 2
lost_bytes.png (324.08 KiB) Viewed 460 times

rtlsdrblog
Site Admin
Posts: 1726
Joined: Mon Nov 19, 2012 11:54 pm

Re: USRP TX/RX. Lost bytes and "U" in flowgraph execution

Post by rtlsdrblog » Sat Apr 21, 2018 3:16 am

Those UU's mean buffer underruns, caused by your computer not being fast enough, or the USB transfer not being fast enough.

pilot327
Posts: 3
Joined: Fri Apr 20, 2018 7:15 am

Re: USRP TX/RX. Lost bytes and "U" in flowgraph execution

Post by pilot327 » Wed Apr 25, 2018 8:30 am

rtlsdrblog wrote:
Sat Apr 21, 2018 3:16 am
Those UU's mean buffer underruns, caused by your computer not being fast enough, or the USB transfer not being fast enough.

Thank you. How can I know characteristics of data processing usrp1 and computer?

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