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Spectrum labeling tool

This tool enables generating training datasets for machine learning algorithms that aim to learn from spectrum waterfall plots. The tool presents random excerpts of the spectrum to the user and records manually input rectangle labels.

Getting started

The rest of this section assumes a Linux machine is being used.


Python3 is required to run this tool. To install dependencies run:

$ pip install numpy matplotlib Pillow

Before running the tool, input data files in an appropriate format (see section Data) must be specified using the spectrum_f_names parameter.


To start the tool, run the following command:

$ python

To record a label, use the left mouse button: click, hold, draw a rectangle and release the mouse button. To undo, press the right mouse button. Press space to display the next spectrogram. At the end of the labeling procedure, the tool outputs a file containing recorded labels.


The following parameters may be configured inside the file:

  • base_data_path - The base data path for input spectrum files.
  • spectrum_f_names - Input spectrum files' names.
  • output_directory - Tool's output directory.
  • window_duration - Length (in seconds) of random spectrum excerpts presented to the user.
  • rand_skip_forward_range - Interval (in seconds) from which the distance between two consecutive spectrum excerpts is uniformly randomly selected.
  • noise_cutoff - Sets the spectrogram values that are below noise floor + noise_cutoff to noise floor.


The input files should be in JSONL format with an object on each line having the following properties: Time (ISO 8691 datetime format, yyyy-mm-ddThh:mm:ss.ffffff) and Measurements (array of power measurements in dBm). Example:

{"Time":"2017-06-06T00:00:00.032083","Measurements":[-126, -125, -125, ..., -126, -126, -126]}
{"Time":"2017-06-06T00:00:00.259549","Measurements":[-129, -131, -131, ..., -130, -130, -129]}
{"Time":"2017-06-06T00:20:17.617085","Measurements":[-130, -130, -131, ..., -130, -130, -130]}

Recorded labels are output to a specified directory using the same file name as corresponding input files with a prepended word out. The format is as follows:

1496700657.135960 1496700686.904408
{'StartChannel': 241, 'EndChannel': 507, 'StartTime': 1496700671.218505, 'EndTime': 1496700677.859333}
{'StartChannel': 651, 'EndChannel': 786, 'StartTime': 1496700664.753048, 'EndTime': 1496700669.790228}
{'StartChannel': 74, 'EndChannel': 142, 'StartTime': 1496700662.348393, 'EndTime': 1496700662.974746}

1496701299.129764 1496701328.897681
{'StartChannel': 756, 'EndChannel': 921, 'StartTime': 1496701309.778328, 'EndTime': 1496701314.414673}
{'StartChannel': 645, 'EndChannel': 750, 'StartTime': 1496701315.21587, 'EndTime': 1496701315.843185}
{'StartChannel': 2, 'EndChannel': 1022, 'StartTime': 1496701308.175178, 'EndTime': 1496701309.377631}


For each spectrum excerpt, UNIX timestamp of first and last displayed data point is recorded. Following is a list of labels, where StartChannel and EndChannel represent the first and last FFT bin of the label respectively and StartTime and EndTime represent the start and stop time (UNIX timestamp) of the label respectively.

An example spectrum dataset together with generated labels is available at

Author and license

Spectrum labeling tool was developed by Timotej Gale,

Copyright (C) 2019 SensorLab, Jožef Stefan Institute

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see


This tool enables generating training datasets for machine learning algorithms that aim to learn from spectrum waterfall plots.







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