I'm recording and replaying interleaved shorts @ 8Msps.. how is the benchmarking software called? I also have noticed a diffference between my main, old gnuradio installation and a fresh one just done from trunk on another disk... the fisrt is all right with transmissions up to 4 MHz the second stops at 2MHz, (using the same scripts of mine on both installations): when, on the fresh installation, I ask for 4MHz I can hear only noise being sent out (I think this is a different problem than the slow flow).. I'm a bit confused...
thanks vincenzo 2007/9/7, Firas abbas <[EMAIL PROTECTED]>: > > Hi Vincenzo, > > Are you recording the 8Msps complex or short ?. In recording, I always > prefer the interleaved complex short, because the real coming samples from > the USRP across the USB is 16 bit short. The conversion to float (32 bit) > complex is being done by software in the PC and thus adds no new information > and does not enhance the data. It only complicate file storage process. If > converting to short does not solve your problem, try to record and play > smaller bandwidth like 6.4MHz (decimation 10) or less. Also test your > PC USB 2 speed by using the benchmark software found the gnuradio truck. > > Best Regards, > > Firas > > *Vincenzo Pellegrini <[EMAIL PROTECTED]>* wrote: > > 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 > > > > Discuss-gnuradio@gnu.org > > > > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > > > > > > > > > > > > > > > > > > > > -- Vincenzo Pellegrini
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