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Re: [Discuss-gnuradio] interfacing a DSP array card to USRP2
From: |
Jeff Brower |
Subject: |
Re: [Discuss-gnuradio] interfacing a DSP array card to USRP2 |
Date: |
Wed, 31 Mar 2010 15:32:44 -0600 (CST) |
User-agent: |
SquirrelMail/1.4.2-1 |
Firas-
>> From: Jeff Brower <address@hidden>
>>
>> Firas-
>> A couple of brief comments:
>> 1) Sounds like this was a
>> high-speed data acq card, optimized for streaming, not an accelerator
>> card. How big was the
>> FIFO?
>
> The FIFO was 64MByte.
That's huge... and you mentioned a 64k block transfer, much smaller, but still
more than 40 times a large Ethernet
packet. It sounds to me like this particular card mfg was focused on very high
rate streaming (without gaps or drops)
and not on low-latency, small transfers. I would guess they didn't set up
their driver to optimize small transfer
sizes. Maybe even the board didn't support a small size, for example if the
FIFO had to contain a minimum number of
channels and/or data length before it could assert "not empty".
-Jeff