[USRP-users] Help improving USRP B200 throughput

Martin Braun martin.braun at ettus.com
Sun Sep 7 05:52:58 EDT 2014


Hey Jason,

sorry for not giving you an answer sooner. As you already pointed out,
USB3 high rate operations is still a bit wonky in general; with USRPs,
you don't only need to be able to sustain high rates, but also to keep
them up reliably without backing up.

Four questions:
- What exactly do you mean by x% reliability?
- What's your CPU usage during ops?
- Have you tried benchmark_rate to see if your app has an influence?
- Have you tried other machines for testing purposes, see if other USB
chipsets or hardware matter?

M


On 09/04/2014 10:57 PM, Jason Heym via USRP-users wrote:
> Bumping this thread...
> 
> Any suggestions?
> 
> On Fri, Aug 29, 2014 at 6:47 PM, Jason Heym <jpheym at gmail.com> wrote:
>> I have been testing a recently-purchased USRP B200 with an Asus G750 laptop.
>>
>> My goal is full duplex 32 million samples/second TX and RX.
>> Reliability is very important. This is for some radar experiments that
>> need maximum TX and RX bandwidth continuously for periods of several
>> minutes.
>>
>> Please see the attached test results.
>>
>> Note I'm doing TX and RX of 50M samples for each run. So each run
>> represents a few seconds of TX and RX. Fewer samples per run will have
>> less chance of interruption and produce higher success rates. But my
>> goal is interruption-free operation over at least a few minutes.
>>
>> Basically for 2 to 8 MSPS symmetric (TX and RX) reliability is around
>> 50% to 60%. At 16 MSPS reliability drops to 25%. At 32 MSPS there is
>> total failure. Reducing the RX data rate while keeping the TX rate
>> fixed can improve success rates. However the opposite (reducing TX
>> data rate and keeping RX fixed) does not help. I do need symmetric
>> data rates.
>>
>> What can I do to improve the throughput or better diagnose and address
>> the problem?
>>
>> I prefer a laptop for portable / field operation. This laptop performs
>> well with a Point Grey Grasshopper3 USB 3.0 camera, achieving 350
>> MB/second error-free for extended periods (a few hours). Obviously
>> this is mostly camera-to-host throughput, not symmetric full duplex.
>>
>> The B200 and AD9361 have enormous potential. I just need to improve
>> the throughput situation. I recognize that USB 3.0 SuperSpeed has its
>> challenges, probably especially for full-duplex symmetric throughput.
>>
>> Thank you!
>> Jason Heym
> 
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