decoding errors

[Erik Lechak]

Hello,

When I run rtl_433 I do not see any devices.  When I run it with the "-vvv" flag it seems to detect all kinds of devices around me, but I think I'm getting decoding errors that stop the reporting.

I've only had my device for a week, so I am sure that I am doing something wrong.  I've been able to use sdrpp, gqrx, and sdtrunk to receive broadcasts.  Every day seems to present me with a new brick wall, but I have not been able to get past this one.

I compiled rtl_433 from source and tried the older one in the xubuntu repository and they both give me the same result.  The cmake command didn't find any missing libraries.

I've spent hours running with several flags, and searching for the error messages to no avail.

Any suggestions would be greatly appreciated.

I'm on Xubuntu Linux 24.04.1

This is the Nooelec RTL-SDR v5 Bundle that I am using:
https://www.amazon.com/dp/B01GDN1T4S


These are the commands that I ran followed by their output:


>> rtl_433 -Y autolevel -M level -M noise

OUTPUT

rtl_433 version 24.10-5-g0acfa816 branch master at 202411131210 inputs file rtl_tcp RTL-SDR SoapySDR with TLS
Detached kernel driver
Found Rafael Micro R820T tuner
[SDR] Using device 0: Nooelec, NESDR SMArt v5, SN: 00000001, "Generic RTL2832U OEM"
Exact sample rate is: 250000.000414 Hz
[R82XX] PLL not locked!
Allocating 15 zero-copy buffers
[Auto Level] Estimated noise level is -16.9 dB, adjusting minimum detection level to -13.9 dB
[Auto Level] Estimated noise level is -18.6 dB, adjusting minimum detection level to -15.6 dB
[Auto Level] Estimated noise level is -19.9 dB, adjusting minimum detection level to -16.9 dB
[Auto Level] Estimated noise level is -21.1 dB, adjusting minimum detection level to -18.1 dB
[Auto Level] Current noise level -29.5 dB, estimated noise -21.1 dB
[Auto Level] Estimated noise level is -22.2 dB, adjusting minimum detection level to -19.2 dB
[Auto Level] Estimated noise level is -23.9 dB, adjusting minimum detection level to -20.9 dB
[Auto Level] Estimated noise level is -25.3 dB, adjusting minimum detection level to -22.3 dB
[Auto Level] Estimated noise level is -26.3 dB, adjusting minimum detection level to -23.3 dB
[Auto Level] Estimated noise level is -27.3 dB, adjusting minimum detection level to -24.3 dB
[Auto Level] Estimated noise level is -28.3 dB, adjusting minimum detection level to -25.3 dB
[Auto Level] Current noise level -29.4 dB, estimated noise -28.8 dB
[Auto Level] Estimated noise level is -29.3 dB, adjusting minimum detection level to -26.3 dB
[Auto Level] Current noise level -29.5 dB, estimated noise -29.4 dB
[Auto Level] Current noise level -29.5 dB, estimated noise -29.5 dB
[Auto Level] Current noise level -30.0 dB, estimated noise -29.9 dB
[Auto Level] Current noise level -30.0 dB, estimated noise -30.0 dB
[Auto Level] Current noise level -29.7 dB, estimated noise -29.7 dB






>> rtl_433 -Y autolevel -M level -M noise -vvv

OUTPUT [ABRIDGED]

...
[Protocols] Registered 231 out of 267 device decoding protocols
[Input] The internals of input handling changed, read about and report problems on PR #1978
[SDR] Found 1 device(s)
[SDR] trying device 0: Nooelec, NESDR SMArt v5, SN: 00000001
Detached kernel driver
Found Rafael Micro R820T tuner
[SDR] Using device 0: Nooelec, NESDR SMArt v5, SN: 00000001, "Generic RTL2832U OEM"
Exact sample rate is: 250000.000414 Hz
[R82XX] PLL not locked!
[SDR] Sample rate set to 250000 S/s.
[Input] Bit detection level set to 0.0 (Auto).
[SDR] Tuner gain set to Auto.
[Input] Reading samples in async mode...
[SDR] rtlsdr_set_center_freq 433920000 = 0
[SDR] Tuned to 433.920MHz.
[acquire_thread] acquire_thread enter...
Allocating 15 zero-copy buffers
[Auto Level] Estimated noise level is -16.9 dB, adjusting minimum detection level to -13.9 dB
[Baseband] low pass filter for 250000 Hz at cutoff 25000 Hz, 40.0 us
[Auto Level] Estimated noise level is -18.7 dB, adjusting minimum detection level to -15.7 dB
[Auto Level] Estimated noise level is -20.0 dB, adjusting minimum detection level to -17.0 dB
[Auto Level] Estimated noise level is -21.1 dB, adjusting minimum detection level to -18.1 dB
[Auto Level] Estimated noise level is -22.2 dB, adjusting minimum detection level to -19.2 dB
[Auto Level] Estimated noise level is -23.8 dB, adjusting minimum detection level to -20.8 dB
[Auto Level] Current noise level -29.1 dB, estimated noise -23.8 dB
[Auto Level] Estimated noise level is -25.0 dB, adjusting minimum detection level to -22.0 dB
[calibeur_rf104_decode] DECODE_FAIL_SANITY data all 0x00 or 0xFF
[radiohead_ask_extract] preamble not found
[philips_aj3650_decode] wrong number of bits (1)
[radiohead_ask_extract] preamble not found
[ttx201_decode] Short preamble: 1 bits (expected 17)
[ecowitt_decode] Preamble not found
[pulse_slicer_pcm] Security+ (Keyfob)
codes     : {20}00000
[markisol_decode] bits_per_row[0] = 1
[rainpoint_decode] bit_per_row 3 out of range
[jasco_decode] invalid bit count 7
[regency_fan_decode] Expected 21 bits, got 1.
[emos_e6016_decode] Repeated row fail
[emos_e6016_rain_decode] Repeated row fail
[tpms_tyreguard400_callback] Bad message in row 0 need 88 bits got 1
codes     : {1}0
[watts_thermostat_decode] Preamble not found
[rosstech_dcu706_decode] bit_per_row 10 out of range
[risco_agility_decode] Preamble not found
[Auto Level] Estimated noise level is -26.4 dB, adjusting minimum detection level to -23.4 dB
[calibeur_rf104_decode] DECODE_FAIL_SANITY data all 0x00 or 0xFF
[calibeur_rf104_decode] DECODE_FAIL_SANITY data all 0x00 or 0xFF
[acurite_986_decode] row 0 bits 1, bytes 5
[radiohead_ask_extract] preamble not found
[radiohead_ask_extract] preamble not found
[philips_aj3650_decode] wrong number of bits (2)
[radiohead_ask_extract] preamble not found
[radiohead_ask_extract] preamble not found
[ttx201_decode] Short preamble: 1 bits (expected 17)
...

Thanks,

Erik

[Michael Cadiere]

Have you tried just running

rtl_433 -v

[Christian Z.]

Always good to start with minimal options, but in this case the -M options are useful debug infos and -Y autolevel is needed to decode anything with those very low dB levels.

It seems the levels are suspiciously low. Maybe play with manual gain.

The verbose decoder messages are not much help, most decoders will fail most of the time ;) Better to use -A to see the bits. E.g.

rtl_433 -v -Y autolevel -M level -M noise -A

[Erik Lechak]

Yep.  I've run no-v,  -v, -vv, -vvv, and -vvvv

I've tried adjusting gain (-g), sample rate (-s),  and just about every other flag that I could wrap my head around.

I was trying to get it to just spit out raw data without decoding with the -X flag, but I couldn't figure out how to use it.

I think the "v" flag is just how verbose the debug information is.

>> rtl_433 -Y autolevel -M level -M noise  -v

With "-v" I get something similar to no-v.  I don't see the "wrong number of bits", "DECODE_FAIL_SANITY", "Preamble not found", or other decode error messages.  I also don't get any detected devices.  Just a bunch of "Auto Level  Current noise level" messages.

[Erik Lechak]

I started with the bare minimum, then spent hours trying tons of flags.  On youtube it looks like you just type rtl_433 and like magic it shows you everything around you.

I'm embarrassed to admit how ignorant I am in this field, but could you please give me a few examples of what to set the gain to.  Like do I use : "-20",  "20",  "-20db".  Could you give me a range, and an example of the command line.

I get some kind of result with the command line you asked me to run.  I'm not sure what to do with the information.

>>  rtl_433 -v -Y autolevel -M level -M noise -A

OUTPUT [abridged]

...

Detected OOK package 2024-11-18 15:54:35
Analyzing pulses...
Total count:    4,  width: 1.31 ms (  328 S)
Pulse width distribution:
 [ 0] count:    1,  width:   72 us [72;72] (  18 S)
 [ 1] count:    2,  width:   44 us [44;48] (  11 S)
 [ 2] count:    1,  width:    0 us [0;0] (   0 S)
Gap width distribution:
 [ 0] count:    1,  width:  680 us [680;680] ( 170 S)
 [ 1] count:    2,  width:  232 us [228;240] (  58 S)
Pulse period distribution:
 [ 0] count:    1,  width:  752 us [752;752] ( 188 S)
 [ 1] count:    2,  width:  280 us [272;288] (  70 S)
Pulse timing distribution:
 [ 0] count:    1,  width:   72 us [72;72] (  18 S)
 [ 1] count:    2,  width:   44 us [44;48] (  11 S)
 [ 2] count:    1,  width:    0 us [0;0] (   0 S)
 [ 3] count:    1,  width:  680 us [680;680] ( 170 S)
 [ 4] count:    2,  width:  232 us [228;240] (  58 S)
 [ 5] count:    1,  width:   28 us [28;28] (   7 S)
Level estimates [high, low]:     14,      1
RSSI: -30.7 dB SNR: 11.5 dB Noise: -42.1 dB
Frequency offsets [F1, F2]:   -1028,      0 (-3.9 kHz, +0.0 kHz)
Guessing modulation: No clue...
view at https://triq.org/pdv/#AAB1060048002C000002A800E8001C839494A555

...

Detected OOK package 2024-11-18 15:54:35
Analyzing pulses...
Total count:    6,  width: 7.13 ms ( 1782 S)
Pulse width distribution:
 [ 0] count:    4,  width:   48 us [44;56] (  12 S)
 [ 1] count:    1,  width:   72 us [72;72] (  18 S)
 [ 2] count:    1,  width:    0 us [0;0] (   0 S)
Gap width distribution:
 [ 0] count:    1,  width: 2956 us [2956;2956] ( 739 S)
 [ 1] count:    3,  width: 1072 us [1068;1080] ( 268 S)
 [ 2] count:    1,  width:  680 us [680;680] ( 170 S)
Pulse period distribution:
 [ 0] count:    1,  width: 3004 us [3004;3004] ( 751 S)
 [ 1] count:    3,  width: 1124 us [1124;1124] ( 281 S)
 [ 2] count:    1,  width:  752 us [752;752] ( 188 S)
Pulse timing distribution:
 [ 0] count:    5,  width:   48 us [40;56] (  12 S)
 [ 1] count:    1,  width:   72 us [72;72] (  18 S)
 [ 2] count:    1,  width:    0 us [0;0] (   0 S)
 [ 3] count:    1,  width: 2956 us [2956;2956] ( 739 S)
 [ 4] count:    3,  width: 1072 us [1068;1080] ( 268 S)
 [ 5] count:    1,  width:  680 us [680;680] ( 170 S)
Level estimates [high, low]:     18,      2
RSSI: -29.6 dB SNR: 9.5 dB Noise: -39.1 dB
Frequency offsets [F1, F2]:     869,      0 (+3.3 kHz, +0.0 kHz)
Guessing modulation: Pulse Width Modulation with multiple packets
view at https://triq.org/pdv/#AAB00F06010030004800000B8C043002A88355+AAB01306010030004800000B8C043002A884849584A055
Attempting demodulation... short_width: 48, long_width: 72, reset_limit: 2960, sync_width: 0
Use a flex decoder with -X 'n=name,m=OOK_PWM,s=48,l=72,r=2960,g=1084,t=10,y=0'
[pulse_slicer_pwm] Analyzer Device
codes     : {1}8, {0}0, {2}8, {0}0

...

[Christian Z.]

That's too few bits for sensible messages (e.g. {1}… is 1 bit ). Also RSSI -30 dB is bad, you normally would expect near -0 dB, maybe -10 dB. And -42 dB for noise is dead silent, it's the lowest the RTL-SDR can go. Something is wrong with your antenna, cables or gain.

Gain is 0 to ~50, with -v you should see the actual gain printed as "Tuner gain set to …"