Improved Unmanned Aerial Vehicle Noise Direction Finding System

The work is devoted to the development of the acoustic direction of creation of means of detection of unmanned aerial vehicles (UAVs). The work of these tools is based on the principles of noise direction finding with the use of such variable characteristics of the acoustic field as: sound intensity, frequency spectrum and spatial spectrum. The architecture of UAV detection devices on the acoustic field corresponds to the algorithms of reproduction in separate paths of the device of ideology of registration and control of dynamics of change of characteristic of an acoustic field which defines the specified change as the fact of detection. The technical implementation of the above detection devices is to create a path of parallel octave, 12 octave and 13 octave filters, a path of narrowband filtering and a path of detection by power (intensity).

The ideology of construction of detection devices is based on variability and physical manifestations of changes in such 
characteristics of acoustic noise as: sound intensity in the space — time interval of observation, broadband filtering, narrowband filtering, correlation characteristics.

To ensure the detection of acoustic power (or intensity) with subsequent measurement of the level, the counter-inclusion (by switching or using operational amplifiers) of the elements of the cross-shaped group is used. An important and new feature is that one of the linear discrete acoustic antennas with an enlarged base additionally has two more pressure receivers symmetrically relative to the phase center.

For broadband filtration, a comb of 13 octave band and semi-octave filters is used. In turn, the path of the narrowband spectrum is an octave band filter and a unit for calculating the fast Fourier transform. 

The path of the correlation direction-finding method implements the determination of changes in the autocorrelation coefficient and the corresponding electrical parameter (say the current through the display circuit) in the processing path in situations of fixing the direction to the target.

Therefore, the proposed system for detecting useful noise signals should contain four paths, the physical implementation of detection in which is performed by software implementation of detection algorithms and, threshold processing and indication of results.

In order to improve and increase the reliability of detection, the direction finder is supplemented by the path of detection on the mutual spectrum and the path of the correlation method of direction finding.

The processing of input acoustic information of the type of specific noise-like signal is carried out by using the instrumental laboratory software package Lab View and Math Lab. We will add that the article contains theoretical and  practical results of measurements of noise loading and range of action of a noise direction finder. Experimental studies in terms of detection and measurement of the main characteristics of the device were conducted in laboratory and field conditions.

At the same time, the present demonstrates the rapid development of the UAV fleet, which determines the urgency of the work and the development of the device as a means of counteracting small aircraft of various recognitions is its goal.