Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
Hi vincenzo, No need to be confused , lets put it together again: 1) The USB benchmark software can be found in the gnuradio/gnuradio-examples/python/usrp/benchmark_usb.py 2) What do you mean by another disk? are both gnuradrio installation work from the same operating system ? or each drive has its own OS? 3) What is you OS? 4) What is the reading of [hdparm -t /mnt/sda ] on both drives? 5) Describe you setup please and what do you want to do. Fortunately, for one day or less, I have function generator and spectrum analyzer in my home with the USRP system and I can run a copy of your experiments at my home to see the result on my system. Firas Vincenzo Pellegrini [EMAIL PROTECTED] wrote: 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
Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
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
Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
I've just checked, at 4 MHz I can not only tune the central station of my fm band, really I can perfectly tune all them, all the stations in the snaphotted band, even at he extremes, the CIC roll off reall gives me no problem at this stage.. with 8 MHz all this good stuff is simply ..gone enormous amount of noise and what I can hear is clearly being sent out slower than it's due.. any hint? thanks vincenzo ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
Vincenzo Pellegrini wrote: I've just checked, at 4 MHz I can not only tune the central station of my fm band, really I can perfectly tune all them, all the stations in the snaphotted band, even at he extremes, the CIC roll off reall gives me no problem at this stage.. with 8 MHz all this good stuff is simply ..gone enormous amount of noise and what I can hear is clearly being sent out slower than it's due.. Do you get overruns? That means your machine can't keep up. Matt ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
really I was expecting them but I cannot see them, they should be in the terminal right? like uO when receiving and uU when transming right? I cannot see these ones thanks On Wed, 2007-09-05 at 16:35 -0700, Matt Ettus wrote: Vincenzo Pellegrini wrote: I've just checked, at 4 MHz I can not only tune the central station of my fm band, really I can perfectly tune all them, all the stations in the snaphotted band, even at he extremes, the CIC roll off reall gives me no problem at this stage.. with 8 MHz all this good stuff is simply ..gone enormous amount of noise and what I can hear is clearly being sent out slower than it's due.. Do you get overruns? That means your machine can't keep up. Matt ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
Vincenzo Pellegrini wrote: Matt, ...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... I really don't know what you're looking for here. There are a lot of people transmitting a lot of different signals with the USRP and not having issues. There are some things you seem to be missing, though. No system is capable of using 100% of the nyquist bandwidth, and the USRP is no exception. On receive, our passband is flat out to about 75 or 80% of nyquist. For 8 MS/s complex sampling, that gives more than 6 MHz of flat bandwidth. On transmit, there are no halfband filters in there, so you will see more rolloff from the CIC filters. If this is a problem, you have 3 options: - If your generated signal is at less than 8 MS/s complex, then you should just upsample in software. - If your generated signal is at the full 8 MS/s then you can predistort your signal to compensate for the CIC rolloff. - Otherwise, I would suggest making a new FPGA image with halfband filters in the TX side. You can make room in there by removing one receive chain (leaving only one). Matt PS There is no need to send emails to both the list and to me. I am on the list, and don't need 2 copies of every email. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
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
Re: [Discuss-gnuradio] 8MHz Tx Bandwidth.. Nightmare and Fear
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 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 -- View this message in context: http://www.nabble.com/8MHz-Tx-Bandwidth..-Nightmare-and-Fear-tf4374848.html#a12471008 Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
