When plasma instabilities arise in the post-sunset time, the so-called ionospheric plasma bubbles may develop, causing amplitude fades and phase oscillations, decreasing the availability and quality of transionospheric communication systems. In the regions where these bubbles appear, deep signal fading may occasionally reach the lowest levels and with loss of signal received for a certain period. In this work, a characterization of deep power fades is performed supported by a dataset covering 5 months of high-rate monitoring data collected at four different locations in Brazil in distinct S₄ scenarios for the three available frequencies. Two aspects of the deep fading events were evaluated, the deepest fading attained per minute and the fading events deeper than −15 dB. The inter-frequency analysis showed that as S₄ increases, the number of −15 dB fading occurrences increases for all bands and stations. The average number of occurrences reached approximately 7 and 9 cases per minute, respectively, for Presidente Prudente and São José dos Campos. Statistical analysis for fading events deeper than −15 dB obtained probabilities of 1.61%, 2.87% and 3.97%, respectively, for L1, L2C and L5 at Presidente Prudente. Regarding the value of the deepest fading event per minute, the larger difference between L1, L2C and L5 exhibits values around −11 dB at Presidente Prudente. For this station, the average deepest fading values achieved in L2C and L5 bands were nearly twice that of the L1. The results regarding the probability of a deepest fading less than −20 dB per minute for L5 signal present a probability of 1.38% in Fortaleza, while for Presidente Prudente and São José dos Campos, these values were 5.62% and 3.34%.

当日落后出现等离子体不稳定性时，可能会产生所谓的电离层等离子体气泡，导致振幅衰减和相位振荡，从而降低跨电离层通信系统的可用性和质量。在出现这些气泡的区域，深度信号衰落可能偶尔会达到最低水平，并且在一段时间内接收到的信号会丢失。在这项工作中，深度功率衰减的特征得到了一个数据集的支持，该数据集涵盖了在巴西不同 S _{4 的}四个不同位置收集的 5 个月的高速监测数据三种可用频率的场景。评估了深度衰落事件的两个方面，每分钟达到的最深衰落和深度超过 -15 dB 的衰落事件。频间分析表明，当 S ₄增加，所有频段和电台的 -15 dB 衰落发生次数增加。普鲁登特总统和圣若泽杜斯坎波斯的平均发生次数分别达到每分钟约 7 起和 9 起。对于 Prudente 总统府的 L1、L2C 和 L5，对深度超过 -15 dB 的衰落事件的统计分析获得的概率分别为 1.61%、2.87% 和 3.97%。关于每分钟最深衰落事件的值，L1、L2C 和 L5 之间的较大差异在Presidente Prudente 的值约为-11 dB。对于该台站，L2C 和 L5 频段实现的平均最深衰落值几乎是 L1 频段的两倍。关于 L5 信号每分钟小于 -20 dB 的最深衰落概率的结果在 Fortaleza 中的概率为 1.38%，