Can't seem to find any signal

[aram535]

Hopefully it's okay to post a support request here, if not please let me know when I can post.

I have a 15 year old ceiling fan that I'm trying to capture the RF signals for (to be used in esphome transmit). Using SDR# I can see the signal pretty easily but can't seem to find any signals using rtl_433.

Hardware: Windows 10, RTL-SDR, dipole antenna (20" long, 9.75" each) about 4' away from the signal (tried moving further too). USB is right off the back of the computer.

> rtl_433_64bit_static.exe -f 304.595M -A -v -Y minlevel=-25 -M level
rtl_433 version 25.02 branch  at 202502191252 inputs file rtl_tcp RTL-SDR
[Protocols] Registered 238 out of 275 device decoding protocols [ 1-4 8 10-12 15-17 19-23 25-26 29-36 38-47 49-60 63 67-71 73-85 87-100 102-105 108-116 119-122 124-128 130-149 151-161 163-168 170-175 177-197 199 201-215 217-232 234-241 243-244 246-247 249-259 261-269
[Input] The internals of input handling changed, read about and report problems on PR #1978
[SDR] Found 1 device(s)
[SDR] trying device 0: RTLSDRBlog, Blog V4, SN: 00000001
Found Rafael Micro R828D tuner
[SDR] Using device 0: RTLSDRBlog, Blog V4, 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...
[R82XX] PLL not locked!
[SDR] Tuned to 304.595MHz.
[Baseband] low pass filter for 250000 Hz at cutoff 25000 Hz, 40.0 us

Ref: https://fcc.report/FCC-ID/KUJCE9103

[zuckschwerdt]

Likely Blog V4 problem. -A should output a detection per second or more. Search for how to install librtlsdr updated for Blog V4.

[aram535]

Downloaded and updated the DLLs however still seeing no signal on that frequency. I can pickup a local FM station easily ... false reading obviously but it is working. Any other thoughts on what could be blocking me?

[zuckschwerdt]

I don't think it's about the frequency. Are you getting transmissions from FM stations with rtl_433?

Did you try -Y autolevel -M level -M noise -- what levels are shown?

Maybe take a short recording (rtl_433 -v 304.6M -w file_304.6M_250k.cu8 -T 20s) and view it in https://triq.org/pdv3/ or upload here as zip.

[aram535]

Yes, a local FM station can be tuned to.

304.6M isn't very busy..

[Auto Level] Current noise level -38.2 dB, estimated noise -38.3 dB
[Auto Level] Current noise level -38.2 dB, estimated noise -38.3 dB
[Auto Level] Current noise level -38.3 dB, estimated noise -38.3 dB
[Auto Level] Current noise level -38.0 dB, estimated noise -38.2 dB

here is an updated capture, triq does show the 304.6 frequency signal but it isn't clear on the button presses start/end. In SDR# I can clearly see the signals so that's why I figured I'm doing something wrong with rtl_433.

file_304.6M_250k.cu8.zip

[zuckschwerdt]

The file looks ok, but rather quiet and there is no signal visible. Perhaps take a few more recordigs to see if you can capture the signal. (Compare to any signal from https://github.com/merbanan/rtl_433_tests/tree/master/tests to see what it should look like.)

For an RTL-SDR -38 dB is near the resolution limit (-42 dB), the AGC should usually raise the levels more.