Final Report of BeJamDetect Project 
af the eigenvalues, while the strongest eigenvalue starts to span the sub-space of the Jamming 
signal. 
ın Figure 4-15 the increase of the spread of eigenvalues can be clearly observed over short time 
oeriods but several time within the month. A close-up view of one of such events is presented in 
-igure 4-17. 
Working with the spread of eigenvalues of the array covariance matrix for interference detection 
allows to easily recognise the potential RFI events and roughly assess their strength just by observing 
the corresponding plot like the one in Figure 4-15. However, a more fomalised one-value test metric 
could be practical for screening big volumes of measurement data. Therefore, a practical RFI 
detection metric based on the eigenvalues has been proposed to compute as as follows: 
2 Nant 1 
Troise = Nant/ Den /2 
JNR = 1010g10 (Az 
OpoiseNant n=1 A) 
where A, is the n-th eigenvalue, Na; Is the number of antenna elements in the array, i.e. Nant = 4 
in the case of Demonstrator 2. The RFI metric can be considered as an estimation of the jJamming- 
to-noise ratio (JNR). Under this name the metric is displayed in the GUI of the demonstrator (see 
Figure 4-8). Figure 4-16 shows the RFI detection metric corresponding to the eigenvalues plotted 
in Figure 4-15. 
RFI detection ı metric 
x 
Y 9 61020 
1 TI 
"—  =RFI metric 
v7 
2222 
X We 
X 
y—— 
. 
06-Mav 
>4per 
X ab, «022, C8:49:1 
| Y 1.94316 
Al 
09-Mav 
— m, — — — L 
lay 18-May 21-May 24-May 27-May 30-May 
UTC time 2022 
Figure 4-16: RFI detection metric, May 2022 
In Figure 4-16 it can be observed, that the individual short interference events occurred 
approximately one or two times per day between 8th until 26th of May, where the increase of the 
spread of eigenvalues can be clearly observed over short time periods several times in the month. 
A close-up view of one of such events is shown in Figure 4-17. 
Figure 4-17 presents the plots for the used detection and performance metrics with a closer view 
on the potential jamming event on May 12, 20:40 UTC. As can be observed in Figure 4-17a, several 
peaks of the RFI detection metric can be observed between 20:40 and 20:45. Each of the peaks 
Fitle: Final Report 
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