In this research, a passive radar aimed at the detection of unmanned aerial vehicles was developed. As a UAV navigates at low altitudes and high speeds, RTL-SDR modules are used that with the help of two antennas, one directional and one reference, the position of the object is detected through bounce and signal discrimination, for which several tests were carried out in based on frequencies that are in the FM range. For this, GNU radio is used and data processing with Python in the Anaconda guide that facilitates obtaining data visually through a video of the frequency of the Doppler effect vs the distance in kilometers. Also, mention is made of the synchronization arrangement that is established between the RTL-SDR modules based on their oscillator.