rtldavis not getting any package

[Guido Cioni]

I have installed rtldavis as advised here https://github.com/lheijst/rtldavis and also took care of compiling my own librtlsdr as advised here https://groups.google.com/g/weewx-development/c/L5Lt8x87I_s/m/PP5AdFnQAQAJ.

After doing that I don't get anymore the message "Allocating 1 zero-copy buffers".

Unfortunately it still does not find the signal from my Vantage Vue ISS that I just turned on with the battery. 

Here is the log that I'm getting 

12:27:00.837238 rtldavis.go VERSION=0.15
12:27:00.837746 tr=1 fc=0 ppm=0 gain=87 maxmissed=51 ex=0 receiveWindow=300 actChan=[0] maxChan=1
12:27:00.837789 undefined=true verbose=false disableAfc=false deviceString=0
12:27:00.839045 BitRate: 19200
12:27:00.839100 SymbolLength: 14
12:27:00.839134 SampleRate: 268800
12:27:00.839167 Preamble: 1100101110001001
12:27:00.839200 PreambleSymbols: 16
12:27:00.839233 PreambleLength: 224
12:27:00.839266 PacketSymbols: 80
12:27:00.839327 PacketLength: 1120
12:27:00.839363 BlockSize: 512
12:27:00.839396 BufferLength: 2048
Found Rafael Micro R820T tuner
12:27:01.278886 Hop: {ChannelIdx:0 ChannelFreq:868077250 FreqError:0 Transmitter:0}
Exact sample rate is: 268800.001367 Hz
12:27:01.469509 Supported tuner gain: 0 Db 9 Db 14 Db 27 Db 37 Db 77 Db 87 Db 125 Db 144 Db 157 Db 166 Db 197 Db 207 Db 229 Db 254 Db 280 Db 297 Db 328 Db 338 Db 364 Db 372 Db 386 Db 402 Db 421 Db 434 Db 439 Db 445 Db 480 Db 496 Db
12:27:01.495140 SetTunerGain 87 Successful
12:27:01.495258 GetTunerGain: 87 Db
12:27:01.495315 SetFreqCorrection 0 ppm Successful
12:27:01.499374 Init channels: wait max 17 seconds for a message of each transmitter
12:27:19.437189 Init channels: wait max 17 seconds for a message of each transmitter
12:27:19.437549 Hop: {ChannelIdx:0 ChannelFreq:868077250 FreqError:0 Transmitter:0}
12:27:37.376191 Init channels: wait max 17 seconds for a message of each transmitter
12:27:37.376373 Hop: {ChannelIdx:0 ChannelFreq:868077250 FreqError:0 Transmitter:0}

I'm on a Raspberry Pi 4 with bullseye

[Greg Troxel]

[I'm answering here, but really this belongs on -users!]

Guido Cioni <guido...@gmail.com> writes:

> I have installed rtldavis as advised
> here https://github.com/lheijst/rtldavis and also took care of compiling my
> own librtlsdr as advised
> here https://groups.google.com/g/weewx-development/c/L5Lt8x87I_s/m/PP5AdFnQAQAJ.
> After doing that I don't get anymore the message "Allocating 1 zero-copy
> buffers".
> Unfortunately it still does not find the signal from my Vantage Vue ISS
> that I just turned on with the battery.

You didn't say what other testing you have done. I would recommend
installing rtl_433 and listening on 433.92 MHz, 315 MHz, 915 MHz if in
the US, and some other set if you are in a different ITU/regulatory
region. (One of the main rtl_433 contributors is in .de, so the docs
should have good hints for Europe (868 MHz?) -- but basically I mean the
license-free frequencies.)

I hear quite a number of devices that aren't mine. This will let you
know if your dongle and toolchain is working. You can also assess
frequency stability. The cheap dongles are cheap! I have two of those
and one "NESDR SMArTee v2" which has a TCXO.

Your log shows 868 MHz. That seems like EU, and I wonder if you are
sure that your ISS is the EU version. They are on 915 in the US.

I also hear people say that the dongle should be remoted from the RPI
via a USB cable, to reduce noise.

Take the pi out to 10 feet away from the ISS, line of sight, and try it there.

[Guido Cioni]

Hey, sorry for not clarifying further and for using this group but I couldn't really find a lot of useful information on -user and it seems that more topics about rtldavis can be found here. 

I do have quite a lot of experience with rtl dongles (I have about 4 of them active and capturing stuff in different bands), so I know that the problem is not related to that but specifically to rtldavis and/or the associated GO environment. 

As a matter of fact I use the same dongle to successfully receive data from a Oregon weather station with weewx (using rtl_433), so, as you said, the rtl toolchain is indeed working.

I'm indeed in the EU so the frequency should be good (the ISS is also the EU version). 

Guido Cioni

[Guido Cioni]

I also tried to do a quick scan with the dongle and I can indeed see the transmission from the ISS, only rtldavis is not able to get it 

here is the waterfall from the dongle 

[Guido Cioni]

Ok I've solved the issue by re-doing a frequency scan.

The doc are far from clear and I had to do some trial and errors before finding these frequencies that are working for me 

868127250, 868247250, 868367250, 868497250, 868657250

I still cannot receive outside humidity though. 

[Guido Cioni]

So, I finally got it. After using a constant frequency shift of 50000 Hz (with the option -fc) I was able to receive all the packages. It seems not to miss any measurement which is really good!