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Re: [Discuss-gnuradio] the best file system for reading fast
From: |
Vincenzo Pellegrini |
Subject: |
Re: [Discuss-gnuradio] the best file system for reading fast |
Date: |
Thu, 06 Sep 2007 00:22:59 +0200 |
first of all thanks to all the guys who provided very useful tips for
the the HD+File system setup.
I finally have a 7200rpm disk that does keep up very well with 32MBps
and, I guess, even much more..
is then this assumption correct?
8Msps with gr_complex data type ==> 8e6*8bytes per sample = 64 MB/s
8Msps with interleaved shorts ==> 8e6*2bytes per int * 2channels = 32
MB/s
I'm sure now that my drive can keep up with recording and replaying the
32 MB/s
and I guess that even 64 with my new, xfs formatted clean disk is fine
my problem is that in both cases ( both using complex and interleaved
shorts)
If I work with a 4 MHz bandwidth everything looks allright.
I can record and replay a 4 MHz fm band and perfectly listen to the
station at the center of it when sending it back to the receiver
but
when I try to go 8 MHz I can hear a noisy, extremely weak replica of my
signal, which is SLOW... like an old cassette player with flat batteries
and this is consistent with the fact that a file meant to last 10.717
secs @ 32MB/s, when played with usrp_interp= 16 (8MHz Bandwidth)
lasts MORE than 13 secs, while if played with usrp_interp=32 (4MHz),
it lasts exactly the double of the correct value ie: 10.717*2=21.434
has this ever happened to anybody.. am I making huge mistakes that I
havent discovered yet?
thanks
vincenzo
Re: [Discuss-gnuradio] the best file system for reading fast, Eric Blossom, 2007/09/04
Re: [Discuss-gnuradio] the best file system for reading fast, Chris Stankevitz, 2007/09/04