On 07/24/2018 11:42 PM, RizThon via USRP-users wrote:
I have used the b2x0 radios for some applications myself, we have
had no luck sampling much higher than 30MS/s. I think real-world
USB3 speeds max out around 100MB/s.
Will
Thanks Will, that matches my experience. At 28MS/s it tells me I need
to stream at 112MB/s.
You cannot stream faster than about 30Msps from the B210 when in
dual-channel mode. This is a limitation of the data bus
architecture on the AD9371 chip, and not strictly a limitation of
the B2xx FPGA.
Sorry for the misunderstanding. On the B210, I'm in *single channel*,
RX only, and I start having overruns at 28MS/s.
You can try using the "num_recv_frames" option in the device
argument--I'd suggest trying 128 and 256.
I'll also note that, near as I can tell, LimeSDR drivers dont' reliably
report overruns, so you may be getting them without knowing about it.
I was just giving my experience with a Lime where I can stream in dual
channel, RX only, at 56MS/s. In that case though the Lime sends its
data back as SC12, meaning it can pack a bit more samples.
FYI, we fixed a couple of sc12/8 related issues on our latest master
branch. As Marcus says, if you're doing dual channel on the B210, you
can only go to 30.72 Msps though.
Should I play with the OTW format? Does the B210 handle SC12
(https://files.ettus.com/manual/structuhd_1_1stream__args__t.html
mentions/Only some devices/for SC12).
I tried rx_samples_to_file.exe from
http://files.ettus.com/binaries/uhd/latest_release/Windows7/uhd_3.12.0.0-release_Win32_VS2014.exe
. If I choose SC8, then I can stream faster. It seems I can go up to
49MS/s without error, over 20 seconds.
At 50MS/s and up I get an error
rx_samples_to_file.exe --null --time 20 --freq 2450e6 --gain 50 --spb
10000 --rate 50e6 --wirefmt sc8
[ERROR] [STREAMER] The receive packet handler caught a value exception.
ValueError: bad vrt header or packet fragment
Error: Receiver error: ERROR_CODE_BAD_PACKET
I modified the code to allow --wirefmt sc12, I also get an error, even
at 28MS/s
[ERROR] [STREAMER] The receive packet handler caught a value exception.
ValueError: bad vrt header or packet fragment
but again I'm not sure if the B210 handles that format .
UHD 3.13 is just out, so I tried
http://files.ettus.com/binaries/uhd/uhd_003.013.000.000-release/Windows-7-x86_64/uhd_3.13.0.0-release_Win32_VS2014.exe
. I now get 2850 overruns at 28MS/s in SC16, while I'd get up to 5
with the previous version. In SC8 I can go up to 40MS/s only, instead
of 49. With the x64 version I get similar results. So for now I
reverted back to 3.12.
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