On Tue, 2008-11-11 at 08:26 +0100, Vincenzo Pellegrini wrote: > Martin , > sorry for the delay. My exams seem to have gone well even if it's not > official yet. Great > I also had to do a demo for a company I have a temporary > contract with for developing some gnuradio based gsm-r security > sentinels. Also the demo was smooth. (i already listed the project on > the gnuradio wiki) Good work. > so i really hope i'll be able to prepare the 8Mhz stream for you > within the next 2/3 days. Would this still be useful? Yes it really would.
I am also really looking forward for the sources. One of the things I am planning to do is use the structure of your code as a basis for a DVB-T receiver. It is always easier debugging a receiver when you can make a full loop. (transmitter and receiver back-to-back) Greetings, Martin > 2008/11/3, Martin DvH <[EMAIL PROTECTED]>: > > > > On Mon, 2008-11-03 at 14:13 +0100, Martin DvH wrote: > >> > >> > >> > >> ________________________________ > >> > >> > Van: [EMAIL PROTECTED] > >> [mailto:[EMAIL PROTECTED] > >> Namens Vincenzo Pellegrini > >> > Verzonden: maandag 3 november 2008 0:16 > >> > Aan: Martin DvH > >> > CC: discuss-gnuradio > >> > Onderwerp: [Discuss-gnuradio] Re: Soft-DVB DVB-T transmitter > >> > > >> > > >> > This is Great... :) > >> > > >> > Yup, the playback cannot be smooth because of the wrong throughput, > >> definitely. > >> > Did you use the USRP1 with interpolation factor = 16 ? > >> Yes I did. > >> > > >> > I can prepare a modulated signal with the correct throughput for > >> you.. this is not a problem... :) > >> > > >> Please do, this would be great. > >> > what hard disc are you playing your signal back from? > >> > >> Internal 2.5" harddisk of my acer 6930 notebook (Aspire 6930G-734G32BN > >> LX.AVB0X.135) > >> 2.5" 320GB HDD 5400rpm, SATA > > I checked now. It is a: > > Western digital Scorpio 320 GB SATA (WDC WD3200BEVT-22ZCT0) > > 2.5-inch SATA Hard Drive 320 GB, 3 Gb/s, 8 MB Cache, 5400 RPM > > > > Benchmark from tomshardware (h2benchw 3.6): > > http://www.tomshardware.com/charts/2-5-hard-drive-charts/Minimum-Read-Transfer-Performance,687.html > > minimum read transfer rate 33.5 MB/sec > > average read transfer rate 52.2 MB/sec > > maximum read transfer rate 68.2 MB/sec > > > > > > > >> I am not at home right now So I can't check the exact brand and model of > >> the > >> harddisk. > >> It can do around 38 MB/sec so this is just enough (required 32 MB/sec) > >> > >> I also have 4GB of memory in this notebook, so I think it will buffer the > >> complete file. > >> > >> I had to use my notebook because with my desktop PC (ASrock > >> 939-DUAL-SATA2) > >> The USB TX bandwidth is less then 32 MB/sec. > >> (Which is strange because I CAN receive 32 MB/sec) > >> I get UuUuUu on this machine when useing interpolation 16, so unusable. > >> > >> Regards, > >> Martin > >> > >> > > >> > regards > >> > > >> > vincenzo > >> > > >> > > >> > 2008/11/3 Martin DvH <[EMAIL PROTECTED]> > >> > >> > >> > >> Hi, > >> > >> > > In fact: 8 complex Msps implement a 7 MHz channel while > >> 9.142857143 > >> > > complex Msps implement an 8 MHz channel. > >> > > Just try to go as close as possible to such sampling > >> frequency by > >> > > using USRP2 and let me know what happens... it could > >> turn out that we > >> > > need a resampler block. > >> > So if I use a fractional rate resampler with interpolation > >> factor > >> > 10/8=1.25 I get a 7 Mhz channel with 10 Msps samplerate. > >> > If I use a fractional rate resampler with interpolation > >> factor > >> > 10/9.142857143=1.09375 I get a 8 Mhz channel with 10 Msps > >> samplerate > >> > > >> > If I use a fractional rate resampler with DECIMATION > >> factor > >> > 9.142857143/8=8/7=1.142857143 I get a 8 Mhz channel with 8 > >> Msps > >> > samplerate with the out-of-band skirts folded back at the > >> sides. > >> > > >> > Would be interesting to see if this last one works with a > >> USRP1. > >> > > >> > I'll let you know how the experiments go. > >> > >> I resampled and scaled your ofdm_40.dump file so it now will > >> use 8 Mhz bandwidth with a 8 Msps samplerate. > >> The reception never can be perfect this way but it seems > >> good enough for > >> tests. > >> > >> My USB DVB-T receiver receives the transport stream without > >> problems. > >> Mplayer playes the stream without problem for two loops and > >> then crashes > >> with a broken frame. > >> My standalone settopbox DVB-T receiver now also receives the > >> stream. > >> (8 MHz channel on UHF) > >> It has big problems displaying it. Sound is only a chop of > >> sound now and > >> then and video stops, then runs for a second, then stops > >> again. > >> > >> I think this is because the timestamps and framerate > >> (playout speed) > >> don't match the data throughput of the MPEG stream anymore. > >> (It is getting the stream too fast) > >> > >> I put my resampled RF file at: > >> > >> http://www.olifantasia.com/projects/gnuradio/mdvh/OTA/DVB-T/ofdm_40_bw8Mhz_s > >> amplerate_8Msps_cshort.raw > >> > >> format is complex signed short integers (I 16 bit, Q 16 bit) > >> at 8 > >> Msamples/sec. > >> > >> > >> Greetings, > >> Martin > >> > >> > >> > >> > > more details will follow as soon as I find some time... > >> > Thanks and success with your second group of tests. > >> > > >> > Martin > >> > > best regards and greetings > >> > > to all fellow GNURadioers > >> > > > >> > > vincenzo > >> > > > >> > > PS > >> > > Rafael, just have a look back a this thread and you'll > >> find all the > >> > > info you need to do your test broadcast. Thanks for your > >> interest > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > > >> > > 2008/10/31 Martin Dudok van Heel > >> <[EMAIL PROTECTED]> > >> > > Hi Vincenzo. > >> > > How are things going with your exams. > >> > > > >> > > I hope well. > >> > > > >> > > Thanks for your help so far. > >> > > > >> > > I finally got your DVB-T dump streams working. > >> > > I first tried using an undersampled basicTX but > >> never got it > >> > > to work. > >> > > (use a niquist mirror in the VHF range on > >> channel 11 or 12 > >> > > (219.5 Mhz or 226.5 Mhz)) > >> > > > >> > > I now use a RFX900 and that works with a > >> pinnacle PCTV-Solo > >> > > 72e usb DVB-T receiver card plugged into my PC. > >> > > I use 858.0 Mhz (channel 69) > >> > > I used a 10 dB attenuator on the antenna output > >> to limit > >> > > output power. > >> > > I also modified the RFX900 to enable > >> transmitting outside of > >> > > the ISM band. (disable saw-filter. add 220 pF > >> capacitor) > >> > > > >> > > Apparantly the pinnacle 72e can receive 7 Mhz > >> channels on the > >> > > UHF channels. > >> > > My standalone settopbox DVB-T receiver can't > >> handle it. > >> > > > >> > > I noticed you don't use the full possible range > >> in your 16 bit > >> > > streams. > >> > > (only goes from -80 to +80 while you could use > >> -8192 to 8192) > >> > > Is this on purpose? > >> > > I can multiply samples by 64 and get a cleaner > >> signal. (But > >> > > also more output power) > >> > > > >> > > > >> > > I do have a request, I hope it is not too much > >> work. > >> > > Could you make a stream with 10 Msamples/sec > >> samplerate and 8 > >> > > Mhz wide channel. > >> > > This way I can use standard standalone DVB-T > >> receivers and > >> > > don't have the 7Mhz bandwith on UHF problem. > >> > > > >> > > For the 10 Msps stream I would have to use my > >> USRP2 to output > >> > > it. > >> > > It has a 100 Mhz DAC (in stead of 64 Msps in the > >> USRP1) > >> > > It has a gbit ethernet connection for the > >> samples, so I can go > >> > > up to 25 Msps. > >> > > It can only do fixed interpolation rates so I > >> have to choose > >> > > from the table below. > >> > > (8 Msamples/sec is not supported on the USRP2) > >> > > > >> > > > >> > > USRP2 > >> > > dac_rate interp ethernet_sample_rate > >> > > 100 4 25 > >> > > 100 5 20 > >> > > 100 6 16.67 > >> > > 100 7 14.29 > >> > > 100 8 12.5 > >> > > 100 9 11.11 > >> > > 100 10 10 <----I think 10 > >> Msamples/sec > >> > > should be optimal > >> > > 100 11 9.09 > >> > > 100 12 8.33 > >> > > 100 13 7.69 > >> > > 100 14 7.14 > >> > > > >> > > > >> > > I think 10 Msamples/sec would be a good > >> candidate. > >> > > > >> > > Have you also tried using 8 Msamples/sec on the > >> USRP1? > >> > > I know there would be no room left for IF > >> channel filtering, > >> > > but it could in theory still work. > >> > > If this works I would also very much appreciate > >> a 8Mhz > >> > > bandwidth stream with 8 MSPS samplerate so I can > >> demonstrate > >> > > with a standard USRP1. > >> > > > >> > > Thanks for your help so far. > >> > > I appreciate it very much. > >> > > > >> > > And good luck with your exams. > >> > > > >> > > Have a nice weekend. > >> > > > >> > > Greetings, > >> > > Martin > >> > > > >> > > > >> > > > >> > > > >> > > -- > >> > > Vincenzo Pellegrini > >> > >> > >> > >> > >> > >> > >> -- > >> Vincenzo Pellegrini > >> > >> > >> > >> > >> > >> > >> > >> _______________________________________________ > >> Discuss-gnuradio mailing list > >> [email protected] > >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >> > > > > > > _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
