---------- Forwarded message ---------- From: *Federico Larroca* <flarr...@gmail.com> Date: Friday, November 27, 2015 Subject: DVBT project receiver probelm To: Ihab Zine <ihab.zin...@gmail.com>
Hi Ihab, You only answered to me, maybe you should forward your mail to the list. Regarding the grc, I would also remove the channel model (used for simulations), as in my experience it consumes much CPU. best Federico 2015-11-27 7:22 GMT-03:00 Ihab Zine <ihab.zin...@gmail.com <javascript:_e(%7B%7D,'cvml','ihab.zin...@gmail.com');>>: > ------------------------------ > Hi Frederico,Marcus and > > *Ron* > > *I just got access to the system, ill try to follow what you have told me > guys and ill let you know how it goes.* > > > *Thanks* > > *Ihab * > > On 26 November 2015 at 17:22, Federico Larroca <flarr...@gmail.com > <javascript:_e(%7B%7D,'cvml','flarr...@gmail.com');>> wrote: > >> Hi Ihab, >> Those "restart aquisition" are generated by the ofdm_sym_acquisition >> block when it does not find a peak on the correlation function he uses to >> detect the beginning of the OFDM symbol. You should verify there is indeed >> a DVB signal precisely at 570 MHz. To do this you may use our "Sym Align >> OFDM" block (not a very nice name) available with gr-isdbt ( >> https://github.com/git-artes/gr-isdbt) and check that you see a >> "triangle" (please refer to the readme, the examples, and even the issues >> on our git). The symbol alignment is totally equivalent between DVB-T and >> ISDB-T. >> Moreover, I see several "O"s, meaning that somewhere samples are being >> dropped. That does not help either. If you do not have a very fast machine, >> you may use at the beginning of the flowgraph a "Stream to Vector" followed >> by a "Vector to Stream" with a very big "Num Items" (some millions). >> best >> Federico >> >> 2015-11-26 12:59 GMT-03:00 Ihab Zine <ihab.zin...@gmail.com >> <javascript:_e(%7B%7D,'cvml','ihab.zin...@gmail.com');>>: >> >>> Hi, >>> >>> I’m trying to receive a live signal from an antenna on the roof through >>> a cable connected to my SDR (hackrf one ).The bandwidth of the DVB-T in >>> ireland is 8 Mhz , and the parametetrs Here in ireland as following: >>> >>> Bandwidth: 8 MHz >>> Stream code rate (hi prio): FEC 2/3 >>> Stream code rate (lo prio): FEC 2/3 >>> Modulation: QAM 64 >>> Transmission mode: 8k mode >>> Guard interval: 1/32 >>> Hierarchy: none >>> >>> net_data_rate = 24.128 Mbits/s >>> >>> I used dvbt_rx_demo_8k_QAM64_rate78.grc flow graph with the following >>> changes : >>> >>> - >>> >>> frequency of hackrf one = 570 Mhz, sampling rate = ((8*8e6)/7). >>> - >>> >>> Cyclic Prefix to (8192/32, is this right?) >>> - >>> >>> Code Rate HP : 2/3 >>> - >>> >>> Code Rate LP : 2/3 >>> - >>> >>> Guard Interval : 1/32 >>> >>> The problem i have is that no output data coming out after the >>> demod_reference_signals BLOCK(no cancellation map), and got the following: >>> >>> restart aquisition >>> >>> OOrestart aquisition >>> >>> d_freq_offset: -5 >>> >>> Od_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> restart aquisition >>> >>> OOd_freq_offset: -5 >>> >>> d_freq_offset: -5 >>> >>> >>> >>> so I had to add a signal source to shift the signal. After shfting the >>> signal i got the following : >>> >>> restart aquisition >>> >>> restart aquisition >>> >>> restart aquisition >>> >>> restart aquisition >>> >>> Orestart aquisition >>> >>> >>> >>> I have read a lot about DVB , mapping ,ofdm and others, i have spent >>> weeks on this but still the same problem, if it is synchronization problem >>> what i should do? >>> >>> So please i need a some help with this problem . >>> >>> >>> >>> Thanks >>> >>> Ihab >>> >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> <javascript:_e(%7B%7D,'cvml','Discuss-gnuradio@gnu.org');> >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >> >
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