[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

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

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


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?



reply via email to

[Prev in Thread] Current Thread [Next in Thread]