Novosibirsk State Technical University (NETI) has proposed its own option for detecting rotary-type drones in urban environments, which will avoid many problems, including those related to industrial espionage.
Unmanned aerial vehicles have recently become not only assistants in various fields of activity, but also a means for illegal actions such as industrial espionage and violation of privacy. In parallel with the development of new UAV models, a search is underway for ways to prevent illegal actions using drones.
One of the ways is to use a radar with a continuous linear frequency—modulated probing signal, suggested by Alina Belonogova, a fourth—year student at the Faculty of Aircraft at NSTU-NETI. According to her, the relevance of the topic is due to the growing number of small rotary-type drones, which require high-precision detection and tracking even at low radial speeds and weak radar signature.
Linear frequency modulation radars (LFM radars) with separate transmitting and receiving antennas are used to detect drones in urban environments. The method is effective, but the accuracy of the devices is limited by discrete and parasitic phase noise.
Discrete noise appears as separate spectral lines or narrow peaks in the frequency domain and is caused by reflected signals from buildings, vehicles, and even birds. Phase noise is a random fluctuation in the phase of a signal caused by oscillator instability or frequency conversion. It appears due to a component with phase-locked frequency and leaks between the transmitting and receiving channels.
Noise increases the overall system noise and, therefore, reduces the likelihood of detecting drones, as well as causing false alarms. To eliminate interference and reduce the number of false alarms, it is necessary to study the methods of designing system parameters and signal processing algorithms.
According to Alina Belonogova, she considered calculating the isolation coefficient between the transmitting and receiving channels to reduce interference power. "The coefficient primarily affects the reduction of parasitic phases, reduces the effect of unwanted reflected signals, and prevents phase distortion, especially in precise phase-sensitive systems such as LFMR. The precisely calculated isolation coefficient also prevents overload of the receiver's input stages due to leakage of a powerful transmitting signal and improves the dynamic range of reception, which is important for weak signals," she said.
In the future, Alina Belonogova noted, the topic will continue with work on the design of an LCHM radar for detecting and monitoring rotary-type UAVs in urban environments. It is also supposed to be modeled at the system level in a special design environment, where you can create a block diagram, set parameters and execute the desired option.