rtl_433 stopped receiving all of my sensors

[bkenobi]

I have a SDR connected to my RPi3B that has been receiving several sensors correctly for months without issue. I noticed my Acurite 5in1 weather station stopped receiving recently for some reason. The batteries went dead last month but after replacing the data has only been sporadic. I had another issue unrelated and was going to use the SDR to test but when I connected it back to the RPi and restarted the service, I am now only getting one or two Acurite tower sensors sporadically (I have 9 Acurite TX592, a Acurite 5in1 weather station, 3 Govee water leak, and a few other misc).

I suppose the 5in1 is several years old and changing the batteries could have cause some strange issue, but I doubt it. Also, that doesn't explain why all of the other sensors disappeared.

My configuration is:
RPi3B running Raspbian Buster

rtl_433 version 23.11-12-g8950dc41 branch master at 202312052040 inputs file rtl_tcp RTL-SDR
Found Fitipower FC0013 tuner
[SDR] Using device 0: Realtek, RTL2838UHIDIR, SN: , "Generic RTL2832U OEM"
Exact sample rate is: 250000.000414 Hz

The command line is:
ExecStart=/usr/local/bin/rtl_433 -R 231 -R 40 -R 176:17104 -M utc -F mqtt://localhost:1883,events=rtl_433[/model][/id]

I tested the device/signal by connecting the SDR to SDRSharp with the rtl_433 plugin. While running I could see spikes for different sensors and depending on how close I was to them I could see the waterfall plot change. The plugin decoded several sensors but it wasn't everything though I don't know if the sdrsharp+rtl_433 plugin are the same as running rtl_433 directly.

If there are any details I can provide to help diagnose what happened please let me know. This has been a very stable setup when running but for some reason it's stopped working almost entirely when the SDR was removed which makes no sense.

[bkenobi]

I stopped the service to collect the information above and when I restarted the service it appears that the SDR is receiving most of the sensors again. I wonder if this is an auto-gain issue?

I did see the weather station pop up in the output a few times, so I know it's also received.

[zuckschwerdt]

Or maybe frequency drift due to temperature. You can look at the input rtl_433 sees with the -F rtl_tcp output. Use a SDR gui with rtl_tcp support to connect to rtl_433 then.

[bkenobi]

I did notice the center of the waterfall was left of all sensor signals. Since the width of the lower strength signals was very narrow, perhaps rtl-433 didnt detect them? Is there a way to have the sdr accept a wider frequency band?

[merbanan]

Is there a way to have the sdr accept a wider frequency band?

Higher sample rate.

[bkenobi]

In SDRsharp I had read that using the default sample rate of 2.4 MSPS might cause the plugin to crash so I down selected to 0.9 MSPS. When I did that I was getting data but only when close to the sensor. I will try changing that and testing again.

However, that doesn't explain why rtl_433 was getting 1 or 2 sensors for a couple days and then all of a sudden all of my sensors are back. There was an issue a couple years ago (issue 1669) that appeared to be resolved with a change to the auto-gain setting. Perhaps the change didn't fix it completely?

#1669 (comment)

I'm not sure if it is related, but I did remove the code that initialized the SDR 10x before actually launching rtl_433 for real late last year when this fix was applied. I can try adding it back in if the issue is auto-gain setting again.

[bkenobi]

I had the power fail over the weekend due to trees in the lines. When power was restored, the sensors were not receiving again. Instead of tinkering with things like i did last time around, I tried adding in the initialization lines that made the rtl_433 service very stable and on first restart of the service the sensors immediately were seen. I don't know if there is an actionable item, but in my experience the fix I linked from issue 1669 did not help in my case.

For reference, the lines that make my system work are the following (10x prime lines prior to actually launching).

ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3
ExecStartPre=/usr/local/bin/rtl_433 -T 3

ExecStart=/usr/local/bin/rtl_433 -R 231 -R 40 -R 176:17104 -M utc -F mqtt://localhost:1883,events=rtl_433[/model][/id]