ELV EM 1000

[sonic74]

Hello!
Sorry to open an issue for this, I couldn't find another way to contact you.
Thanks for sharing your code!
I'm trying to receive readings from the ELV EM 1000 energy meter sensors. Demodulated AM audio:
http://sven.killig.de/SDR/ELV%20EM%201000-S.wav
"-a" log:
http://sven.killig.de/SDR/ELV%20EM%201000-GZ.txt
I just need a short tip how "pulse_distance" (496/978) and "pulse_start distance" (961/1447) correspond to ".short_limit" and ".long_limit". Thanks in advance!

[merbanan]

Ok, pulse avg length = 466 and it looks like that is varies by 1% or so. That means that the distance between the pulses is the information carrier. Then we need to use the OOK_PWM_D type in the struct. Now we just need to tell the bit decoder how to decide between 1 and 0. From the log we can see that the distance is 500 or 1000. So we set the .short_limit in between there, at 750. That way it should be easy to decide if it is one or the other. Data packets typically repeats and so does this signal. After 108 bits (324/3) we have a pulse_distance of 14459. So set the long limit to half of that (7250). That will make the bit decoder decode into the next row of the bit matrix. Now we just need to set the .reset_limit and we set it to twice the pulse distance of 14459 (~30000). And as the buffer to decode bits is 40 (#define BITBUF_COLS 5) and we have 108 pulses then we need to increase it to 108/8=21. Hook up the debug call back and you should now get the bit pattern from the signal. If you are lucky the 3 packets repeat and you only have 108 bits of info to figure out.

[sonic74]

Looks good :-)
http://sven.killig.de/SDR/ELV%20EM%201000-GZ%20decoded.txt

[sonic74]

Actually, perhaps not so good yet: after the 40th (1-based) bit, there are only "0"s. Is there perhaps somewhere else a limit like the "BITBUF_COLS 5" (*8=40) ?
Bits 33-40 always being "1" also looks a bit strange.

[sonic74]

Aah, found it:
if (p->bits_col_idx>4) {
p->bits_col_idx = 4;
}

[sonic74]

Now (and with "BITBUF_COLS=14" (108/8=13,5) it looks better:
http://sven.killig.de/SDR/ELV%20EM%201000-GZ%20decoded.txt