decode, computing efficiency about modem HOT 11 OPEN

That CPU does not have NEON, which then needs to be emulated for the Polar list decoder. It also has very little cache.
You could try to lower the list size or replace list decoding with normal decoding and also lower the OSD decoder order or replace with RS decoding but this all will reduce receiver performance by a large margin.
Instead maybe you should get a more modern CPU with NEON, like the one in the Raspberry Pi 400: It only needs 150 ms to decode Rattlegram messages with the untouched code from the short branch and in only 20 ms when lowering the OSD order to 3 instead of the default 4.

from modem.

You should probably play with the OSD ORDER first and set it to two: CODE::OrderedStatisticsDecoder<255, 71, ORDER> osddec;

And then change the list SIZE to maybe four: typedef SIMD<code_type, SIZE> mesg_type;

See if that helps.

from modem.

from modem.

decode.cc of course ;-)

from modem.

from modem.

keep me posted

from modem.

Hello,

My findings so far.

As I posted above, decode modified with your notes now runs very fast in a RPi 1. I wanted to make a comparison on how robust the alternative version was, and planned to record signals and have them processed by the two decode versions. I wanted to do that in a computer as it runs faster. Now I can see that the modified program ends with segmentation fault after showin Es/N0 data. This only happens in the PC, as it runs fine in a RPi. I also tried downloading the latest version of "modem" and compiling it again, unmodified, and it also gives a segfault. But it works in RPi.
Summary:
modem code, weeks old, unmodified. PC: ok. RPi 1: ok, but takes 10s to decode.
modem code, weeks old, modified. PC: seg fault. RPi 1: ok, fast, robustness not yet compared.
modem code, cloned today, unmodified. PC: seg fault. RPi 1: ok, but takes 10s to decode.
I can provide more detailed information like logs, scripts, etc.
regards

from modem.

You should also update the code repository. I made a lot of SIMD related changes lately that might cause the problems you see. If that does not help, please add more info here, and please give me the output of:
grep -m 1 flags /proc/cpuinfo

from modem.

Hello
The modified program runs fast in a Raspberry pi 1 and the sensitivity or ability to decode weak signals seems just as good as the original program. I am doing more experiments. I plan to set up a permanent digipeater and RF to http gateway running on this old rpi.
regards

from modem.

That's good to hear. I did more improvements in the DSP and CODE repositories and would be interested to know how well they work on the old pi as well.

from modem.