The aim of the search for extraterrestrial intelligence (SETI) is to find technologically capable life beyond Earth through their technosignatures. On 2019 April 29, the Breakthrough Listen SETI project observed Proxima Centauri with the Parkes ‘Murriyang’ radio telescope. These data contained a narrowband signal with characteristics broadly consistent with a technosignature near 982 MHz (‘blc1’). Here we present a procedure for the analysis of potential technosignatures, in the context of the ubiquity of human-generated radio interference, which we apply to blc1. Using this procedure, we find that blc1 is not an extraterrestrial technosignature, but rather an electronically drifting intermodulation product of local, time-varying interferers aligned with the observing cadence. We find dozens of instances of radio interference with similar morphologies to blc1 at frequencies harmonically related to common clock oscillators. These complex intermodulation products highlight the necessity for detailed follow-up of any signal of interest using a procedure such as the one outlined in this work.

寻找外星智能（SETI）的目的是通过他们的技术特征找到地球以外具有技术能力的生命。2019 年 4 月 29 日，突破性聆听 SETI 项目使用 Parkes 'Murriyang' 射电望远镜观测了 Proxima Centauri。这些数据包含一个窄带信号，其特征与 982 MHz 附近的技术签名（'blc1'）大体一致。在这里，我们提出了一个分析潜在技术签名的程序，在人为无线电干扰无处不在的背景下，我们将其应用于 blc1。使用此程序，我们发现 blc1 不是外星技术签名，而是与观测节奏一致的本地时变干扰源的电子漂移互调产物。我们发现数十个无线电干扰实例，其形态与 blc1 相似，频率与常见时钟振荡器谐波相关。这些复杂的互调产品强调了使用本工作中概述的程序对任何感兴趣的信号进行详细跟踪的必要性。