hi Firas, thanks for help!
i'm doing pretty much everything you suggested, and in fact, really!!, I
do think that my HD is doing a very
good work.
nevertheless I keep having the same problem,
this is what I also posted to the list:
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
On Wed, 2007-09-05 at 13:15 -0700, Firas abbas wrote:
> Hi Vincenzo,
>
> Sorry for this delay, but I didn't saw your email in the mailing list
> which I usually check. To solve your problem do :
>
> 1) Buy SATA II harddisk drive
> 2) Put Linux in ext3 partition
> 3) Create a small Ext2 partition for your recordings (about
> 4Gbyte)
> 4) Whenever you want to record or replay
data use this ext2 partition
> 5) When you want to record a new file, move the old file from the Ext2
> partition to another partition Ext3. Always keep in mind that the ext2
> partition should be totally empty before any new recording. Also don't
> forget to empty the Trash after each file deletion from the Ext2
> partition.
>
> I hope I made it clear. For more information send me an email.
>
> Best regards,
>
> Firas
>
>
> Vincenzo Pellegrini wrote:
> On Mon, 2007-09-03 at 20:04 -0700, Eng. Firas wrote:
> > Hi Vincenzo,
> >
> >
> > 1) What is your recording system (PC specifications)?.
> > 2) How fast your hard drive can read/write data? because
> working with 8MHz
> > means that your hard
drive must be able to sustain writing
> 32MByte/sec?
> > 3) Do you use ext2 or ext3 ? Ext2 is very efficient in
> writing.
> > 4) Are you recording complex or interleaved Short 8 MHz
> samples?
> >
> > Firas
>
> first of all thanks for listening Firas,
> I'm using a sempron 3000+, 512MiB of Ram, and the HD is a IDE
> with ext3,
> and yes, 32MB/s is at is nominal limit... I'm using complex
> samples..
>
> to bypass the "slow hd problem" before buying a new one, I was
> just
> storing a very few secs of my sample stream to the ram before
> sending it
> out..
>
> in the next stage of my work I will need an hd which is very
> fast in
>
reading a 32MB/s complex sample stream... what would you
> suggest for the
> kind of HD and for the filesystem?
> >
> >
> > Vincenzo Pellegrini wrote:
> > >
> > > Matt,
> > >
> > >
> > > Tonight
> > > I have been recording slices of commercial FM spectrum,
> all centered
> > > right where a good station transmits,
> > >
> > > the first slice was 300Khz wide,
> > > the second was 2MHz
> > > the third was 4MHz
> > >
> > > then I sent all these signals to my Hifi FM receiver via
> the basicTX...
> > > all went fine and I could hear a good stereo sound from my
>
recordings..
> > >
> > > then I tried my nightmare: the 8MHz slice of spectrum....
> > > the output was extremely weak but you could easily tell
> from what you
> > > could hear that the samples were not being sent out at
> 8Msps: the very
> > > poor audio was also "slow" as it happens when you set the
> interpolation
> > > rate too high, compared to the sample rate your samples
> were taken at...
> > > well, this is not just some attenuation next to the
> shoulder of my ofdm
> > > signal.. this is the whole signal .. gone..
> > >
> > > So, I'm really not asking you, Matt, to solve a problem
> which is my duty
> > > to solve...and don't even want to bother the whole
list
> with this
> > > stuff...
> > >
> > > ...but please say it loud, say it clear: "vincenzo, you've
> made very big
> > > mistakes, because the USRP really can transmit an 8MHz
> wide signal
> > > without distorting it significantly, I've tested it"...
> > >
> > > ..so even if this means that I still got much to learn,
> and much to work
> > > to find out where I'm doing wrong...
> > >
> > > ...well, it would be much better than being forced to give
> up what I'm
> > > working upon..
> > >
> > > please...
> > >
> > > thanks
> > >
> > > vincenzo
>
> >
> > > PS.
> > > I'm using default FPGA configuration...
> > >
> > >
> > >
> > > _______________________________________________
> > > Discuss-gnuradio mailing list
> > > address@hidden
> > > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > >
> > >
> >
>
>
>
>