An Adaptive Threshold Updating Algorithm for PMT-Based Ultraviolet Communication

To address varying environmental conditions, this paper proposes an adaptive threshold updating algorithm for photomultiplier tube (PMT) signals in ultraviolet (UV) communication. The receiver maintains a set of pulse detection thresholds and performs channel estimation for each threshold. Using the channel estimation of both signal and background radiation components, we introduce a method to estimate the bit error rate (BER) corresponding to each threshold. Additionally, an adaptive threshold selection system is developed to dynamically update signal detection in response to changing environments. The accuracy of the optimal detection threshold is experimentally evaluated. The effectiveness of the proposed adaptive threshold algorithm is validated through indoor experiments, where trends in channel estimation results, detection thresholds, and frame error rates (FER) are recorded. Moreover, an outdoor experiment is conducted to verify the algorithm's performance under sunlight. The experimental results demonstrate that the adaptive threshold algorithm effectively adjusts the pulse detection threshold based on the current channel state, ensuring robust communication performance in dynamic channel conditions.