# Enhancing Meteor Observations with Photodiode Detectors
## 2 Existing Instruments
The primary drawback of this device is the need to adjust the gain, set via a potentiometer, according to observational conditions. This approach is impractical as it requires constant human supervision. Additionally, each adjustment of the potentiometer necessitates recalibration to ensure the results provide useful information about the intensity of the phenomenon. Several design errors were found. Firstly, using a potentiometer in a sensitive measurement path is not recommended, as the potentiometer wiper bouncing along the resistive track while being adjusted introduces noise spikes. Secondly, the amplifier lacks filters to limit gain, causing the system to amplify unwanted signals and have a tendency to oscillate. Thirdly, the quality of the power supply is crucial in sensitive measurement systems. While battery power was used for the transimpedance amplifier to address this issue, the power supply for the A/D converter module was neglected. According to the schematic, it is powered from the Arduino Uno's +5 V line. Optimal performance of the converter requires extensive power supply filtering, appropriate PCB trace routing, and separation of analog and digital grounds, which were not implemented. This omission likely results from using pre-made modules connected with wires rather than a dedicated PCB. The authors also failed to provide convincing evidence of the device's proper functioning. No synchronous recording of the device's output signal and camera images was achieved, despite attempts. The only tests conducted, such as moving a hand in front of the sensor, have limited practical significance. It is regrettable that a basic test under conditions of complete photodiode darkness was not performed, as it is simple to execute and provides valuable information about the system's parameters. The efforts of the authors in towards creating a more advanced device are noteworthy [17]. The radiometer consists of nine photodiodes, grouped in three triplets. In every triplet, three BPW34 photodiodes are used, each with its own transimpedance amplifier. An operational amplifier in a non-inverting configuration is used to sum the signals from the individual channels, with its gain manually set via a potentiometer. Thus,the significant drawback of the previous version remains unresolved (though the authors mention that they plan to introduce automatic gain control in the next version). A crucial and beneficial change is the implementation of digital filtering to improve signal quality. However, it is unfortunate that these actions were not preceded by a deeper analysis of the analog section. By optimizing for noise and adding additional filtering, the signal-to-noise ratio (SNR) could be improved even before signal sampling. Importantly, this time the authors verified the device's performance by comparing the radiometric signal of fireballs with their photometric light curves. The topic of building an all-in-one camera and radiometer system for meteor surveillance is also addressed in a master's thesis [18]. This comprehensive work includes not only a description of the hardware and software components but also a detailed analysis of the Bolide Event on 13 April 2021, which occurred between Florida and Grand Bahama Island. Evaluating this work is challenging because the event was recorded using an early version of the radiometer, which, as stated by the author, did not meet the expected standards. Due to insufficient data recording speed, a large gap was observed in the recorded signal. Additionally, the output signal was characterized by an unacceptable level of noise and interference because this earlier radiometer build was unable to filter out light pollution from various sources, as well as circuit noise. Consequently, the obtained radiometric data hold little value. Importantly, the thesis attempts to address these issues. A new version of the radiometer was proposed and implemented. However, the master's thesis does not present results of the radiometer's performance in the presence of a bolide.