# Maritime Over the Horizon Sensor Integration:
## 5 Field Results  
Before the field results are presented, a few things need to be noted:  
1. The graphical environment presented here is used just for the data visualization of the described sensor fusion process, not as the command and control software's GUI. 2. The graphical elements are the following: 1. The yellow markers always represent radar tracks, both fused and single radar. 2. The white markers always represent AIS data. 3. The hexagonal encirclement around the marker means that that marker is selected, and details about the vessel are shown in a separate window. 4. The trace colors are randomly determined and don't have any particular significance. 3. Please note that each vessel has a unique Maritime Mobile Service Identity (MMSI) number assigned to it [30]. In order to demonstrate the algorithm's capabilities in a real working environment, a few possible scenarios will be described here. These scenarios are:  
1. \"Clear case\"--Both radars provide stable and long living tracks. 2. \"New update\"--One radar provides a stable and long living track while the second radar just detected a new target which falls into the gating radius. 3. \"Separated tracks\"--Both radars track a target, but the positions they are providing are significantly different. 4. \"Unstable target\"--The radar(s) are tracking a target, but the data is erratic. First, a so called \"clear case\" will be presented. In such cases both radars are providing stable tracks with minimal position differences (Figure 4). Fused track id No. F_155 consists of radar 0 track id No. 0_116175 and radar 1 track id No. 1_94725. Both radars are providing stable and long-lasting tracks with minimal position differences so the data fusion process is quite simplified. Moreover, there is only one AIS target nearby (MMSI 636014250) which further justifies the data fusion decision. The confidence level is listed in the fused track data window, representing the highest confidence level among all single radar track confidence levels. Next, a new update of an existing track will be discussed. This situation occurs when only one radar provides the data for the fused track for a long time, and a radar track from another radar appears within the fused track gating radius (Figure 5). As can be seen from Figure 5, the fused track id No. F_1240 is regularly updated by radar 1 id No. 1_1697622, so the traces are nearly overlapping. Upon the arrival of a new radar track id No. 0_1042366, originating from radar 0, the fused track shifts slightly towards the new track. However, it is still more aligned to the long track, since it has a longer tracking history and thus a higher confidence level. It is important to note that the long and new tracks are originating from different radars, as otherwise they will not be considered for the fusion process. Furthermore, a fusion of two significantly separated radar tracks is presented. In the situation shown in Figure 6, both radars are tracking the same target; however, the vessel positions they are providing are mutually separated by approximately 3 km. Figure 4: Case” (dark blue trace: radar 0 data, green trace: radar 1 data, purple trace: fused track, red trace: AIS data). From Figure 6, one can see that the fused track id No. F_1267 is formed from radar 0 track id No. 0_1047155 and radar 1 track id No. 1_1707772, despite the radar tracks' mutual distance. This example also demonstrates an \"unstable target\" situation very well, since the fused track is maintained in spite of radar 0's erratic data availability. It can be seen that radar 0 stopped providing target data for some time, as highlighted by the red circle. During that period, the fused track was maintained entirely by the data available from radar 1; hence, the fused track shifted toward the radar 1 track. Upon the reappearance of the radar 0 data, both radar tracks were reintegrated into a single track. This decision is justified since there is only one AIS target in the vicinity (MMSI 538005045).