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Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM
From: |
Ron Economos |
Subject: |
Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM |
Date: |
Thu, 15 Mar 2018 13:40:37 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 |
The test file adv16.cfile is only meant to work with the parameters of
the test flow graph dvbt_rx_8k.grc. Specifically, 16QAM, 2/3 rate, 1/32
guard interval.
The GNU Radio DVB-T receiver is very CPU resource intensive. I have an
E5-1650 based workstation (6 cores/12 threads at 3.6 GHz) and it can
just barely do 64QAM 2/3 rate in an 8 MHz channel.
Depending on your CPU, you may have to drop down to QPSK and/or a
smaller channel size. To change the channel size, change the sample rate
equation from (8000000.0 * 8) / 7 to:
(8000000.0 * 7) / 7 /* 7 MHz */
(8000000.0 * 6) / 7 /* 6 MHz */
(8000000.0 * 5) / 7 /* 5 MHz */
or as low as you need to go to make things work. Note that any overflow
will restart the symbol acquisition, and a chunk of video will be lost
causing glitchy playback. If there are too many overflows, the receiver
will never lock.
Ron
On 03/14/2018 07:46 AM, Juan Antonio wrote:
Hello, I am trying to receive a real channel of 8K 64QAM 1/4 2/3 using
as a base the example dvbt_rx_demo_8k and a hackrf
If I use the adv16.cfile file as a source, the constellation hooks
independently of whether I put 16QAM or 64 QAM (the representation is
only 16 points). But if I do use the hackrf (many
oooooooooooooooooooooo) or the hackrf recording using gqrx (here there
is no ooooooo ) I only get a central point in the output of the FFT block
and many points moving wildly at the exit of the block
dtv_dvbt_demod_reference_signals_0
If the signal does not engage in the constellation in my opinion it is
clear that everything that comes after will not be useful at all
Best Regards
- [Discuss-gnuradio] Problems with dvbt 8k 64QAM, Juan Antonio, 2018/03/14
- Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM,
Ron Economos <=
- Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM, Juan Antonio, 2018/03/15
- Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM, Juan Antonio, 2018/03/15
- Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM, Juan Antonio, 2018/03/16
- Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM, Juan Antonio, 2018/03/16
- Re: [Discuss-gnuradio] Problems with dvbt 8k 64QAM, Juan Antonio, 2018/03/19