# Maritime Over the Horizon Sensor Integration:
## 6 Statistical Analyses  
In this chapter, the statistical analysis of a number of targets received from the HFSWRs in the network and a number of targets forwarded to the further processing is presented. In other words, this analysis shows the percentage of duplicate targets eliminated by the presented algorithm. Before presenting the analysis, a few things need to be pointed out:  
* The period of a whole year is analyzed here. Starting with 1 st of January 2018 and ending with 31 st of December 2018. * Power supply issues are common in the Gulf of Guinea--these are not isolated incidents. Despite the fact that all sites are equipped with UPSs which can power the equipment for approximately 24 h, some sites are located in remote areas and cannot be reached within 24 h. This leads to situations where a significant drop of the number of detected targets from one site is present, simply because the site was with no power. * A similar situation occurs when there is a major problem with the satellite links. The problem mostly occurs when storms are raging in a certain area blocking the satellite communications from sites located in that area. This also causes a significant drop of targets as long as the link is down. * Taking the above two points into account, it can be expected that the number of targets dwindles from time to time and thus creates some sharp differences between adjacent months. In Figure 7, one log file created during the data fusion process is presented. Explanation of the log file fields:  
* Iteration -number of iteration processes during a single day
* Time--time and date when the log file was created
* FOTHR (total)--number of fused tracks in the current iteration
* FOTHR with AIS--number of fused tracks which have corresponding AIS data in the current iteration
* RAD 0--number of tracks received from radar 0 in the current iteration
* RAD 1--number of tracks received from radar 1 in the current iteration
* Total FOTHR--number of fused tracks since the beginning of the day
* Total RAD 0--number of tracks received from radar 0 since the beginning of the day
* Total RAD 1--number of tracks received from radar 1 since the beginning of the day
* Integrated--number of fused tracks which have corresponding AIS data since the beginning of the day  
Based on the data displayed in Figure 7, the following can be concluded:  
1. The total number of targets received from all HFSWRs during this iteration is 22,
2. The total number of fused targets is 17,
3. The number of eliminated targets is 5. Figure 7: One iteration log file. This means that 23% of all targets were duplicated and could cause false alarm triggers in command and control (C2) systems. The log files are collected during the day in order to present the statistics for that day. One daily log file is presented in Figure 8.  
For this day, RAD 0 detected 137 targets, while RAD 1 detected 74 targets, so the HFSWR network detected 211 targets. Overall, 173 targets were delivered to the C2 system, and 80 of those targets have corresponding AIS data, while 38 radar targets were eliminated as duplicates. This means that nearly 20% of all received targets were duplicated. Please note that in this particular case there were more integrated HFSWR tracks than AIS data. The situations vary from day to day. The day log files are collected on a monthly basis starting from the 1 st of January 2018 and ending with the 31 st of December 2018, in order to create a statistical analysis, which is presented in Figure 9.  
Figure 9 shows that around 1200 to 1600 duplicate targets were eliminated every month. Some drops are particularly noticeable during December and January, which can be attributed to the holiday season. In total, for the observed period, the proposed algorithm received 67,799 single radar tracks and, after processing, 52,016 fused tracks were delivered to the C2 system. This means that 15,783 radar tracks were eliminated, since they were duplicates.