# Making Automotive Radar Sensor Validation Measurements Comparable
## 4 Evaluation
### Whole Detections  
In Figure 5 the EDFs and box plots for distance, azimuth, and RCS are visualized. It can be seen that the EDFs for distance are close to each other, but a spread is visible. At a distance of 29.65 m, there is an accumulation of detections, which shows the influence of the CCR. In general, the detections are distributed over a distance of up to 147 m. Close to the sensor, detections are located on the road surface, and with higher distances, the number of detections increases at the transition between vegetation and the road. Furthermore, in the vegetation itself, multiple detections are present. A decrease in the number of detections above 110 m indicates a lower signal-to-noise ratio (SNR), making detections random. Above 147 m, the SNR is so low that there are no more detections in the environment. The median of all \(d_{\text{bias}}\) is similar to \(d_{\text{CAVM}}\) in absolute terms. However, the scatter of the \(d_{\text{bias}}\) values is larger compared with \(d_{\text{CAVM}}\). In addition to the very different number of detections and the large scatter in the metrics, the repeatability of the measurement results for the distance of all detections is very low. The influence of the environment is too large to draw conclusions from the distance evaluation.  
As with distance, the azimuth distribution is affected by the environment. Between \(-5^{\circ}\) and \(5^{\circ}\) the CCR is notable with the step at 0. The visible shoulder area next to 0 indicates a few detections due to the road. The second step close to 0 at negative azimuth angles can be associated with detections at close-range as well as at twice the distance between the CCR and the sensor. The median of \(d_{\text{bias}}\) is about \(0.5^{\circ}\), which is a relatively high value in relation to the sensor's FoV, indicating, in addition to the scatter, a low repeatability of the measurements. The scatter deviation of \(d_{\text{CAVM}}\) confirms this impression.  
Figure 4: EDFs of all five measurements of the CCR on the radar cuboid level. The number of aggregated bins is listed below the diagram. On the right side the box plot for \(d_{\text{bias}}\) and \(d_{\text{CAVM}}\) is shown.  
The CCR is also evident in the RCS EDFs. 5 % of the detections are due to the point target with an approximate 27 dBm\({}^{2}\). This indicates high repeatability with respect to the reflectivity characteristics. However, especially for detections at close-range due to asphalt and vegetation, different distributions show the stochastic behavior of the majority of the detections. As before, \(d_{\mathrm{bias}}\) and \(d_{\mathrm{CAVM}}\) are difficult to interpret because there is too much randomness in the way the detections are generated by the environment. In particular, there is an outlier in \(d_{\mathrm{CAVM}}\), which is due to the comparison of measurements 2 and 5. Here, the number of detections is the most spread over all measurements.  
From the evaluation of all detections, it can be concluded that a comparison of all detections is not useful for the validation of this specific radar sensor. The environment has too much influence on the detection distribution. This evaluation experiment can be used in future validation studies to assess whether an evaluation of all detections is useful in the studied environment in the context of validation measurements.