Re: [Discuss-gnuradio] Possible solution to USRP Packet Dropping

[Marcus Müller]

Hi Moses,

two observations:
1. If buffering 4 billion items (or bytes, or what ever "buffer size"
refers to here) helps, then only because it "smoothens" over the CPU
load by storing away seconds to minutes worth of data. If your computer
needs that long to catch up, something is too slow.
2. Instead of using a buffer block, realize that GNU Radio itself is
buffer based [1]. In the "advanced" tab of any block in GRC you can set
the Minimum Output Buffer Size to your liking, and have a 4 GB buffer
without any ado!

Again, if 4GB of buffering is necessary, your system is probably simply
too slow on average, and you'll run into problems, just a bit later.

[1] https://www.gnuradio.org/blog/2017-01-05-buffers/
On Wed, 2019-08-14 at 19:14 +0200, Moses Browne Mwakyanjala wrote:
> Hello everyone, 
> I'm experiencing packet dropping when I operate the USRP X310 (1GBe,
> 1472 bytes buffer) at high sample rates (around 20 MSamples/Second).
> This severely limits the nominal bit rate I was hoping for. Over a
> year ago, I stumbled upon a presentation [1] where the presenter was
> able to go around the problem by creating a block he called buffer.
> Basically, this block converts high rate complex IQ samples into 2-
> byte char and store them somewhere in RAM. The data is then released
> at a low-enough rate such that subsequent blocks cause no overflows.
> Sadly, the code is not public and I was thinking of writing a similar
> block myself. I'm looking for ideas on how to efficiently reproduce
> his results. All suggestions are highly welcomed. 
> 
> Regards,
> Moses.  
> 
> 
> [1] https://youtu.be/sDz9Ove0Dgc?t=581
> 
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