Rtl_433: Allocating 15 zero-copy buffers

[juergenschubert]

I run on a RaspberryPI and do get the follwoing

pi@RTL-433:~ $ rtl_433 -R 32
Registering protocol [1] "Fine Offset Electronics WH1080/WH3080 Weather Station"
Registered 1 out of 102 device decoding protocols
Found 1 device(s)

trying device 0: Realtek, RTL2838UHIDIR, SN: 00000001
Found Rafael Micro R820T tuner
Using device 0: Generic RTL2832U OEM
Exact sample rate is: 250000.000414 Hz
[R82XX] PLL not locked!
Sample rate set to 250000.
Bit detection level set to 0 (Auto).
Tuner gain set to Auto.
Reading samples in async mode...
Tuned to 433920000 Hz.
Allocating 15 zero-copy buffers

Just wonder what this does and how to troubleshoot this?

[zuckschwerdt]

zero-copy just means fast. Those buffers are for USB data transfer.

[juergenschubert]

Thanks

[zuckschwerdt]

You are not mistaken, the wording there is somewhat scary. But it's from the rtl-sdr lib, nothing we can do about it ;)

[rradar]

hmmm I also get this message and afterwards nothing happens?

[...]
Sample rate set to 250000.
Bit detection level set to 0 (Auto).
Tunre gain set to Auto.
Reading samples in async mode...
Tunes to 433920000 Hz.
Allocating 15 zero-copy buffers

Any ideas what's up or how to debug? @zuckschwerdt @merbanan maybe?

[zuckschwerdt]

Use CubicSDR or Gqrx to verify good reception. Then use rtl_433 with -a or -A switch to see all radio data.

[rradar]

Hi @zuckschwerdt

thank's for the feedback. I'm installing Gqrx right now. Will report back shortly!

[rradar]

Hi @zuckschwerdt
I can't get CubicSDR running because there is no arm binary (for raspberry pi 3) available.
When I try to start gqrx (which installed without problems) I get the following error message:

*** Error in 'gqrx': corrupted double-linked list: 0x01c93300

[zuckschwerdt]

Then maybe run rtl_sdr -f 433920000 -s 250000 -n 15000000 data.cu8 and inspect the data.cu8 with e.g. http://triq.net/iqs
The goal is to see if there is any data reception. Compare the visual output with samples from here https://github.com/merbanan/rtl_433_tests/tree/master/tests to get a feel for it.

[rradar]

Hey @zuckschwerdt

I did it! And it looks there is something?

[rradar]

Wierd. The "15 zero-copy" message is gone.

Now it just stops like this:

[...]
Sample rate set to 250000.
Bit detection level set to 0 (Auto).
Tuner gain set to Auto.
Reading samples in async mode...
Tuned to 433920000 Hz.

[zuckschwerdt]

That looks ok. But the band is completly empty -- no signals. Try another frequency, maybe a known radio station. Say there is an "98.3 FM" then use -f 98300000 and again look at the signal.
Try for different frequencies. Maybe also record 10 minutes worth of data or raise the sample rate to 2048000.

[rradar]

I could getting results with adding the external antenna to the stick and let it run for a longer time.

Thank's for your help!

[gersmit]

Hello you all, hope someone can help me:
i read text above but is not helping me out. I have the problem with "allocating 15 zero-copy buffers". When i start rtl_test after installing RTL_SDR on the RPI 3B+ i get the row "allocating 15 zero-copy buffers". When i run, in my case AIS decoder, then i get decoding for few seconds and stops. What can i do to solve this problem, my other RPI 3B give no problems.
Many tanks for answer and greetings Ger

[zuckschwerdt]

You might want to poke around the rtlsdr issues about this or ask there.

[merbanan]

@gersmit I think this is related to a kernel issue a newer rtl-sdr library might have a workaround fix for that.

https://github.com/steve-m/librtlsdr/commit/f68bb2fa772ad94f58c59babd78353667570630b

So try with the most recent librtlsdr.

[gersmit]

Hi Christian,
Thanks for replay, i did already poke around but nobody reacting. I read the issues above and thought maybe i can find answer here. But not so i think?. Probably it is possible to overrule the zero-copy? i dont no.
If you no something what i can try, please let me no.

Thanks, Ger

[gersmit]

Sorry Christian and Benjamin, did not see commend from Benjamin. Thanks for that and going to try.

[gersmit]

HI Benjamin, can you tell me what is the best way to change the librtlsdr? I am not a specialist.

Thanks Ger

[merbanan]

@gersmit no sorry, it depends on the distribution.

[mojso]

sudo apt-get install librtlsdr0

In rtl_433 no longer shows
Allocating 15 zero-copy buffers

but with librtlsdr0, I can not use rtl_tcp

[merbanan]

I guess you need to compile librtl-sdr on your own.

[mojso]

can you tell me how to do it

[zuckschwerdt]

Describe in more detail what you want and what you already tried. Ask smart.

sudo apt-get install librtlsdr0
In rtl_433 no longer shows: Allocating 15 zero-copy buffers

What did you have installed before? Try find / -name librtlsdr.\*

but with librtlsdr0, I can not use rtl_tcp

The program rtl_tcp is in rtl-sdr package, the librtlsdr0 is only a library.