Re: [Discuss-gnuradio] Hard Disk Bottleneck

[Martin Dvh]

Vincenzo Pellegrini wrote:
> Hi everybody,
> 
> just a quick question: has anybody managed so far to provide the usrp
> with the 8 Complex Msps needed to transmit an 8 MHz wide band?
> 
> My problem is that such a bandwidth yields a 32MiBps throughput and,
> even if the USB2 bus and the CPU speed of my machine are all right with
> this, it looks like my IDE HARD DISK cannot provide such a data rate.
> 
> Can anyone please confirm whether he's been successful in something
> similar, and, if so, with what kind of HD?
> 
> thanks
> 
> vincenzo 
If I have to read/send signals I can't process in realtime I allways do one of 
the following.

Small files:    use a ramdisk
Big files:      use a dedicated partition at the very start of the drive, 
formatted with a fast filesystem (non-journalling) with nothing
further on it.

I have a 2.5 GB fat32 partition at the start of my drive (/dev/hda1).

For RX this can just keep up with 32 MiB/sec.

For TX I never have been able to get more then 16 MiB/sec, even when using a 
ramdisk or using a null_source.

I don't know why there is a difference between TX and RX. Maybe there is a 
subtle buffering, timing or other difference in the communication
with the usrp.

Has anobody else have been able to do more then 16 MiB/sec on the TX side?

Greetings,
Martin


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