How to Calibrate RTL-SDR using Kalibrate-RTL on Linux

YouTube user NeedSec has posted a good tutorial video showing how to use Kalibriate-RTL, a program used to determine the frequency offset error of your RTL-SDR dongle. Every RTL-SDR dongle will have a small frequency error as it is cheaply mass produced and not tested for accuracy.  This frequency error is linear across the spectrum, and can be adjusted in most SDR programs by entering a PPM (parts per million) offset value.

Kalibrate is a Linux program that uses GSM mobile cell phone base stations to determine the PPM offset, by using the GSM signals own frequency correction bursts. See the tutorial video below.

Calibrate RTL-SDR with Mobile Phone or Cell Towers – How to Fix Frequency Offset

13 comments

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  4. arbartz

    So after some trial and error I got Kalibrate to build and install on my RaspberryPi. But when ever I try to do anything with kalibrate I get the following error:

    pi@raspberrypi ~/kalibrate-rtl $ kal -s 900
    shmat: Invalid argument
    terminate called after throwing an instance of 'std::runtime_error'
    what(): circular_buffer: shmat
    Aborted
    pi@raspberrypi ~/kalibrate-rtl $

    Any help would be much appreciated.

    • Travis

      When you build the code, use the following commands:

      git clone https://github.com/asdil12/kalibrate-rtl.git
      git checkout arm_memory
      cd kalibrate-rtl
      ./bootstrap
      ./configure
      make
      sudo make install

      This will check out a branch specific for the ARM processor used on the Rapsberry Pi.

  5. Gethin

    btw

    kal requires fftw3 and version 3.2 or higher of libusrp. kal also requires a USRP and daughterboards appropriate for the desired GSM frequency band. An external clock is not required; kal can also calculate the offset of the built-in USRP clock.

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