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 > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
