The file gnuradio/gr-dtv/examples/README.dvbt2 contains links to TS
files crafted with the correct bitrate for each example flow graph. For
the vv011-1kfft.grc flow graph, it's:
https://www.w6rz.net/vv011-1kfft.ts
The correct invocation for dvbt2rate is:
./dvbt2rate 8 1 2 1966 48 1 1 0 0 3 0
FFT size = 1024
guard interval = 1/8
number of data symbols = 1966
number of FEC blocks = 48
code rate = 1/2
constellation = QPSK
frame size = normal
carrier mode = normal
pilot pattern = PP3
L1 constellation = BPSK
clock rate = 9142857.142857, TF = 249.956000 ms
Normal mode bitrate = 6169661.860487
High Efficiency mode bitrate = 6202654.704661
max symbols = 1984, max blocks = 48
symbols = 1982, max blocks = 48
cells = 1577708, stream = 1555200, L1 = 3344, dummy = 18944, unmodulated
= 220
PAPR max symbols = 1984, max blocks = 48
symbols = 1982, max blocks = 47
cells = 1558048, stream = 1555200, L1 = 3344, dummy = -716, unmodulated
= 220
I'll admit it's a little painful to use. 😳
Ron
On 9/30/24 06:58, Ali G. Dezfuli wrote:
Thanks Ron!
How can I make the related TS file? (e.g. for vv011-1kfft.grc)
The list in https://github.com/drmpeg/dtv-utils does not include QPSK!
On Mon, Sep 30, 2024 at 4:29 PM Ron Economos <w...@comcast.net> wrote:
You could try DVB-T2 configurations that use less CPU. Both
smaller FFT size and lower bitrate help. For example try the
following test flow graphs:
vv009-4kfft.grc 27.588664 Mbps
vv010-2kfft.grc 14.364704 Mbps
vv011-1kfft.grc 6.169662 Mbps
If your receiver allows it, you can also use smaller channel
bandwidths such as 5, 6, or 7 MHz. The bitrate will be scaled
accordingly.
The DVB-T2 bitrate calculator is here.
https://github.com/drmpeg/dtv-utils/blob/master/dvbt2rate.c
Ron
On 9/29/24 22:30, Ali G. Dezfuli wrote:
When I run dvbt2 transmitter examples from gr-dtv without any
hardware, “Probe Rate” block in GRC shows 15e6 samples per second
at the output of the Tx (which needs about 9 Msps to work in
real-time.)
Next, I connected USRP B200mini, but it showed underruns.
Talking to the community, they said UHD is heavy and suggested
other SDR modules like LimeSDR.
But the problem still exists using LimeSDR-USB!
I wonder if there is a way to make “LimeSDR Sink (TX)” catch up
with other blocks.
Details:
HW: Orange Pi 5 plus (32GB)
OS: Ubuntu 22.04
GR: v3.10.11.0
Thanks!
