Evrytania LLC

LTE Tracker


LTE-Tracker is open source software that continuously searchers for LTE cells on a particular frequency and then tracks, in realtime, all found cells. With the addition of a GPS receiver, this program can be used to obtain basic cellular coverage maps.

Download source code and build instructions.

Command line options:

LTE-Tracker -f frequency [optional_parameters]
  Basic options
    -h --help
      print this help screen
    -v --verbose
      increase status messages from program
    -b --brief
      reduce status messages from program
    -i --device-index N
      specify which attached RTLSDR dongle to use
  Frequency options:
    -f --freq fc
      frequency where cells are located
  Dongle LO correction options:
    -p --ppm ppm
      crystal remaining PPM error
    -c --correction c
      crystal correction factor


Launch the tracker to track all LTE cells on 739 MHz:

LTE-Tracker -f 739e6

After a short initial frequency calibration, the program enters its main display screen which provides a list, updated in realtime, of all the LTE cells it is tracking. The program tracks each cell's SNR, frequency offset, time offset, and MIB decoding status.

Furthermore, while all the cells are being tracked, a separate parallel searcher thread is searching for new cells to be added to the tracked cell list. As the receiver is moved around among different basestation coverage areas, it is normal to see new cells pop up and weak cells removed from the display.

LTE-Tracker Main Screen

Above is an example display where 5 cells are being tracked. All cells display their time offset (relative to the dongle's frame timing), the SNR of all the antenna ports, and the SNR of the synchronization channel. The residual frequency offset of the dongle is displayed at the bottom of the screen.

The up/down arrow keys can be used to highlight different ports and pressing 'enter' will display the transfer function of the wireless channel from that port on the basestation to the dongle's antenna.

LTE-Tracker TF view

The screen capture above shows the instantaneous transfer function of port 0 of cell 271. This is a magnitude plot and a phase plot is also available by pressing 'enter' one more time.

While the transfer function is displayed, pressing up/down arrow will switch to displaying the transfer function of different ports.

At any time, press Esc to return to the main menu or 'q' to exit the program.

To view further options (refresh rate, buffer status, etc.), press 'h'.

A dual core i7-2640 cpu can track approximately 4 cells with two antenna ports per cell. If the cell trackers fall too far behind, they will automatically drop some data and a message will be printed on the main screen.

Crystal calibration

LTE-Tracker accepts the same --correction and --ppm options that LTE Cell Scanner did. Please see the documentation forĀ LTE Cell Scanner for details on how to use these options. Proper use of these options will significantly speed up the initial frequency calibration, but will have no effect on the realtime functioning of this program.

Known Issues:

The time offset of all the tracked cells drifts very slowly (about 0.1 time offset samples every second). For perfect tracking it is necessary to know the exact ratio between the sampling rate of the dongle's A/D and the dongle's LO frequency. Crystal frequency offsets will not affect this ratio since both of these frequencies are derived from the same crystal reference. However, because of finite word lengths in the divisors built into the chips, the actual ratio is not simply fs/fc.

See also: LTE Cell Scanner

Video of LTE-Tracker on a drivetest going in and out of the coverage area of several basestations.