Martin , sorry for the delay. My exams seem to have gone well even if it's not official yet. 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) 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?
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 >> Discuss-gnuradio@gnu.org >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > -- Vincenzo Pellegrini _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
