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kopia lustrzana https://github.com/xaelsouth/rtl-wmbus
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Xael South 2021-02-16 09:07:54 +00:00
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11
README.md
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@ -47,19 +47,22 @@ To save an I/Q-stream on disk and decode that off-line:
* rtl_sdr samples.bin -f 868.95M -s 1600000
* cat samples.bin | build/rtl_wmbus
To run continuously:
To save an I/Q-stream and decode this immediately to see what's going on right now:
* rtl_sdr -f 868.95M -s 1600000 - 2>/dev/null | tee samples.bin | build/rtl_wmbus
To run continuously without saving anything on disk:
* rtl_sdr -f 868.95M -s 1600000 - 2>/dev/null | build/rtl_wmbus
To run continuously with rx_sdr (or even with a higher sampling and decimation rate)
* rx_sdr -f 868.95M -s 1600000 - 2>/dev/null | build/rtl_wmbus
* rx_sdr -f 868.95M -s 4000000 - 2>/dev/null | build/rtl_wmbus -d 5
Notice "-d 5" in the last line: it's a multiple of 800kHz resulting from the sample rate of 4000000.
Notice "-d 5" in the last line: it's a multiple of 800kHz resulting from the sample rate of 4MHz.
To count "good" (no 3 out of 6 errors, no checksum errors) packets:
* cat samples.bin | build/rtl_wmbus 2>/dev/null | grep "[T,C,S]1;1;1" | wc -l
Carrier-frequency given at "-f" must be set properly. With my DVB-T-Receiver I had to choose carrier 50kHz under the standard of 868.95MHz. Sample rate at 1.6Ms/s should be used or use a multiple of 800kHz. RTL-SDR supports sampling frequencies up to 3.2MSaples, so you use 1.6MSamples, 2.4MSamples or 3.2Msamples.
Carrier-frequency given at "-f" must be set properly. With my DVB-T-Receiver I had to choose carrier 50kHz under the standard of 868.95MHz. Sample rate at 1.6Ms/s should be used or use a multiple of 800kHz. RTL-SDR supports sampling rate up to 3.2 MSamples, so you can choose 1.6 MSamples, 2.4 MSamples or 3.2 MSamples.
See samples/samples2.bin for a live example with two T1 mode devices inside.
@ -118,7 +121,7 @@ I have tested this so far and can confirm that it works for T1/C1 and S1. Thanks
Optimization on frequencies translation by rearranging compute steps implemented as proposed by alalons.
Alalons (have I thanked you already?!) proposed a speed optimized arctan function. Performance gain is notable (factor ~2) but could reduce sensitivity slightly on receiving C1 mode datagrams. A speed optimized arctan version can be activated by "-a" in the program options.
Alalons (have I thanked you already?!) proposed a speed optimized arctan function. Performance gain is notable (factor ~2) but could reduce sensitivity slightly. I have seen that on receiving C1 mode datagrams - that's why the speed optimized version is not in use by default. A speed optimized arctan version can be activated by "-a" in the program options.
License

5
rtl_wmbus.c
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@ -494,8 +494,9 @@ static void runlength_algorithm_s1(unsigned raw_bit, unsigned rssi, struct runle
return;
}
const int half_bit_length = samples_per_bit/2;
const int run_length = algo->run_length;
if (run_length <= samples_per_bit/2)
if (run_length <= half_bit_length)
{
runlength_algorithm_reset_s1(algo);
algo->state = state;
@ -504,7 +505,7 @@ static void runlength_algorithm_s1(unsigned raw_bit, unsigned rssi, struct runle
}
int num_of_bits_rx;
for (num_of_bits_rx = 0; algo->run_length > samples_per_bit/2; num_of_bits_rx++)
for (num_of_bits_rx = 0; algo->run_length > half_bit_length; num_of_bits_rx++)
{
algo->run_length -= samples_per_bit;