Re: raspberry pi + dvb-t2

[Adrian Musceac]

  Ok, thanks!

On March 18, 2021 1:01:41 PM UTC, Ron Economos <w6rz@comcast.net> wrote:

There are no libvolk optimizations for the LDPC encoder. I don't even think it's possible. The encoder is just a giant XOR, but the XOR operands are not from contiguous locations in memory.

Ron

On 3/18/21 05:42, Adrian Musceac wrote:

Hi Ron,
Tangential to the subject only, do you know if LDPC has optimizations for ARM archs in libvolk? Arm64 mainly.

Thanks,
Adrian

On March 18, 2021 11:54:42 AM UTC, Ron Economos <w6rz@comcast.net> wrote:

I haven't tried it, but it may be possible on a Raspberry Pi 4. I 
wouldn't bother with anything less than a RPi4. I have successfully run 
a modified DVB-T2 flow graph on a Beagleboard-X15, but only at 5 MHz 
channel width (5.714285 Msps).

I've attached the flow graph. It uses short frames and 5/6 code rate to 
limit the amount of LDPC processing. It also sends a lot of dummy 
symbols, again to limit the amount of processing. However, it still 
attains 19.057285 Mbps at 5 MHz channel width. If you can get it to run 
at 8 MHz channel width, the bitrate will be 30.491656 Mbps.

It's also tuned for UHD v3.13.0.3-rc1. If you're using a later version 
of UHD, change send_frame_size=65536 to send_frame_size=8192 in the UHD 
Sink block. Using large USB frames helps to significantly lower 
processor load, but this feature has been removed from later versions of 
UHD.

Ron

On 3/18/21 04:17, Ali G. Dezfuli wrote:
 Hi all,

 Is there any experience in transmitting DVB-T2 with gnuradio and 
 raspberry pi (any version)?
 I just wonder if it can work real-time with about 9 MHz sampling 
 frequency of 8 MHz DVB-T2.
 Thank you!

 BR,
 AGD