## 4 Results
The proposed  
Figure 4: Comparison of multiple target detection under severe weather conditions (**a**) without IIR target 1 and (**b**) with IIR target 1. Figure 3: Comparison of multiple target detection under clear weather conditions (**a**) without IIR and (**b**) with IIR. system incorporates a coherent detection scheme for the analysis of both the intensity and phase of a moving target. To evaluate the system's performance, simulations were conducted with targets moving at varying speeds. The initial target was situated at a distance of 75 m and was moving at a velocity of 50 km per hour. Meanwhile, the second target was placed 55 m away, traveling at a speed of 20 km per hour. The corresponding Doppler frequencies for these targets were computed as 17.91 MHz and 7 MHz, respectively. It is worth noting that the Doppler shift is influenced by the direction of the target. There will be a decrease in range frequency when the target approaches the photonic radar (\(f_{r}-f_{d}\)). As the target distances itself from the photonic radar, the range frequency experiences an increment equal to the Doppler frequency, which can be represented as (\(f_{r}+f_{d}\)). Figure 5 demonstrates the detection of moving targets at different speeds and distances from the photonic radar. The simulation encompasses two distinct scenarios: one where targets are advancing towards the radar, denoted as (\(f_{r}-f_{d}\)), and another where targets are receding from the radar, indicated as (\(f_{r}+f_{d}\)). The numerical simulation results in Figure 5a,b show that the peak range frequencies obtained align with the mathematically calculated values for both scenarios. The graph in Figure 5a displays two peaks for each target observed by the photonic radar. The peak for target 1 when the vehicle is moving away from the radar (\(f_{r}+f_{d}\)) is located at 217.61 MHz, whereas the peak for the vehicle moving towards the radar (\(f_{r}-f_{d}\)) is located at 182.09 MHz. These peaks are highlighted in black and red. Similarly, for target 2, the peak for the vehicle moving away from the radar (\(f_{r}+f_{d}\)) is at 153.30 MHz, while the peak for the vehicle moving towards the radar (\(f_{r}-f_{d}\)) is at 139.30 MHz. These peaks are highlighted in blue and yellow. Figure 5b illustrates how the detection of moving targets is affected by the IIR filter in terms of max. received power. Finally, the photonic radar system undergoes an evaluation for its proficiency in differentiating between targets that are in close proximity to each other, a characteristic known as range resolution. This aspect is crucial for the effectiveness and accuracy of the radar in complex environments. The range resolution (\(L_{RES}\)) is dependent upon the bandwidth of the system as shown in Equation (9) [26]:  
\[L_{RES}=\frac{c}{2B} \tag{9}\]  
Given that a bandwidth of 4 GHz was utilized in this work, the calculated mathematical range resolution, as determined by Equation (9), is 3.75 cm. To conduct numerical simulations, target 1 was placed at a distance of 75 m, while target 2 was positioned 3.75 cm closer to target 1, at a distance of 74.9625 m, based on the mathematically calculated reso  
Figure 5: Comparison of multiple moving targets (**a**) without IIR and (**b**) with IIR for target 1 and target 2.  
lution. Due to the overlapping of the peaks, fractional shifting was performed for target 2, and after several iterations at varying distances, distinct peaks were obtained with a separation margin of 7 cm from target 1 at a distance of 74.930 m. The effectiveness of differentiating between both targets is demonstrated in Figure 6, where clear peaks are observed. Figure 6a illustrates the range resolution without the Infinite Impulse Response (IIR) filter, showing that while the peaks are distinct, part of the target 1 signal overlaps with the noise floor. This could potentially affect the accuracy and robustness of target detection. In contrast, Figure 6b demonstrates the significant improvement achieved with the addition of the IIR filter.