# On-Board Parameter Optimization for Space-Based Infrared Air Vehicle Detection Based on ADS-B Data
## 2 Methodology
### On-Board Parameter Optimization
#### 2.3.2 On-Board Parameter Optimization  
In the process of detection parameter optimization, under the condition that the detection range remains unchanged, the integration time was the major influencing factor, and it was positively correlated with the system performance; that is, \(SNR\) was proportional to the square root of the integration time.  
For the AVD system, there were two aspects that limited the maximum integration time: one was the time for the moving target to fly out of one pixel (the high-resolution imaging system may not exceed 1/4-1/2 pixel as the limit condition); the second was the time from the integration of the superimposed radiation energy of the target and the background to the saturation of the detector pixel. The minimum value of the two was the limit for the maximum integration time. Therefore, \(T_{int\_max}\) is represented as  
\[T_{int\_max}=min\left\{\frac{N_{full}}{P_{max}},\frac{GSD}{v_{tar}}\right\}, \tag{11}\]  
where \(N_{full}\) is defined as the maximum amount of electrons that can be stored within an individual pixel. Generally, based on current detector readout circuit technology, one pixel can have two levels of integral capacitor, and can switch according to the different demands; \(P_{max}\) is the electron flow density per unit time after the detection target is mixed with the background; and \(v_{tar}\) is the real-time flight speed of the air target.  
The on-board parameter optimization steps are described in Algorithm 1. Additionally, the detailed description is as follows:  
```
Input: Parameter \(N_{full}\), \(P_{max}\), \(v_{tar}\), default \(T_{int\_0}\), default integral capacitor gear \(C_{0}\) Output: Parameter maximum \(T_{int\_max}\), matched integral capacitor gear \(C_{m}\)
1: Initialize \(T_{int\_0}\), \(C_{0}\).
2: Calculate \(jSNCR(\cdot_{int\_0},C_{0})\).
3: while (\(jSNCR(T_{int\_max},C_{m})<jSNCR(T_{int\_0},C_{0})\)) do
4: Calculate \(\frac{N_{int\_0}}{P_{max}}\), \(\frac{GSD}{v_{tar}}\).
5: Set \(T_{int\_max}=min\left\{\frac{N_{full}}{P_{max}},\frac{GSD}{v_{tar}}\right\}\).
6: Match integral capacitor gear \(C_{m}\).
7: end while
8: Update parameter \(T_{int\_0}\) as \(T_{int\_max}\), \(C_{0}\) as \(C_{m}\).
```  
**Algorithm 1** On-board Parameter Optimization  
(a) Initialize the integration time \(T_{int\_0}\) and the integration capacitance gear \(C_{0}\) according to the default value to detect the air target;  
(b) After the air target is detected, accumulate multi-frame images to obtain the background radiation characteristics of the current scene, and at the same time receive the ADS-B data of the civil target. Use the flight speed to fit the flight trajectory and process the motion speed estimation, integrate with the mixed target and background radiation characteristics of neighborhood pixel and calculate the maximum integration time \(T_{int\_max}\);  
(c) Match the integral capacitor gear \(C_{m}\) according to \(T_{int}\), and calculate \(JSNCR(T_{int},C_{m})\);  
(d) If \(JSNCR(T_{int\_},C_{m})>JSNCR(T_{int\_0},C_{0})\), update the parameters;  
(e) If the detection inputs such as flight speed and detection background change, steps (b), (c) and (d) are repeated.