[Discuss-gnuradio] DVBT project receiver probelm

[Ihab Zine]

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 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

dvbt_rx_demo_8k_QAM64_rate23_TestComReg.grc.png
Description: PNG image

dvbt_rx_demo_8k_QAM64_rate23_TestComReg.grc
Description: application/gnuradio-grc