Vehicle-Mounted Solar Occultation Flux Fourier Transform Infrared Spectrometer and Its Remote Sensing Application

Abstract

For the demand of rapid monitoring of pollution gas disorganized emissions in industrial parks, this paper studies the solar fast tracker system of vehicle-mounted SOF-FTIR (Solar Occultation Flux Fourier Transform Infrared Spectroscopy) system, where the spectrometer directly measures the broadband absorption spectrum of solar radiation light. A fast portable solar tracking system based on PSD (position sensitive detector) is designed, the mathematical model of solar spot position on the PSD surface source is established, and the optimal optical design parameters are simulated using the model. The dead-zone integral separation PID (Proportion Integration Differentiation) control algorithm is used to track the trajectory of the solar, and the light spot position model is used to nonlinearly compensate the output of PID control so that the PID controller has the same control precision and response speed in different error areas. Experimental analysis of the solar tracking performance of the vehicle-mounted SOF-FTIR under static and dynamic conditions, as well as the spectral effects on the measurements under static vehicle, constant speed, and turning driving conditions. The remote sensing application experiment of vehicle-mounted SOF-FTIR pollution gas emission flux was carried out in a tire factory in Hefei City, Anhui Province. A vehicle-mounted SOF-FTIR system realized the qualitative and quantitative analysis of the pollution gas at the boundary of the tire plant and calculated the flux of each component pollution gas. The emission flux of pollution gas was highly consistent with the actual pollution distribution of the tire plant. The results show that the positioning accuracy of PSD in the vehicle tracking experiment can also meet SOF-FTIR requirements for solar tracking. The remote sensing system will be useful in the field of atmospheric environment monitoring, and the mobile monitoring of regional pollutant gases based on solar infrared spectroscopy has application value.

FFK: Fourier-Transform Fuzzy-c-means Kalman-Filter Based RSSI Filtering Mechanism for Indoor Positioning

“…Thus, FCM can be a better choice than K-means and GF for KF to identify the LOS signals. Also, FT can calculate the frequency of data values [35,36], so FT can identify the long-term stable signal to retrieve stable LOS signals. BLE is supported by most mobile devices, and BLE utilizes low-energy signals which are very sensitive to distance differences [2,14].…”

“…Then, KF moves to the next time interval and uses the new sample value to calculate the prediction value again. Usually, the system error, Q, is set to 0.1 and the measurement error, R, is set to 0.01 [35]. FFK does not use the fixed values but uses the initial 100 RSSI values, which reflect major error offsets, to calculate them, in order to obtain better prediction results.…”

“…where n is the signal propagation constant, d is the distance to be estimated, and A is the RSSI measured value when the distance is 1 m. For the computation complexity, DFT is O (N T 2 ), and IDFT is O (N KM log N KM ), where N T is the size of RSSI T , and N KM is the size of RSSI KM [35,36]. K-means is O (N F ), and FCM is O (N LF ), where N F is the size of RSSI F , and N LF is the size of RSSI LF [34].…”

“…Thus, FCM can assist KF in collecting LOS signals without assuming the distribution of RSSI values is Gaussian. In addition, Fourier Transform (FT) is widely used for signal frequency analysis [35,36], so FT can also filter long-term signals in the low-frequency domain.…”

Design of an Optical Path Scanning Control System in a Portable Fourier Transform Spectrometer Based on Adaptive Feedforward–Nonlinear Proportional-Integral Cascade Composite Control

“…Sulfur hexafluoride has multiple characteristic peaks at 900-1600 cm −1 , and sulfur hexafluoride leakage detection can be carried out through these characteristic peaks [5]. In order to adapt to practical needs, portable FTSs, such as handheld [6,7] and vehicle-mounted [8] FTSs, have emerged. The interferometer is the core component of an FTS, and the miniaturization of the interferometer is the key to its portability [9].…”