SPOTLIGHT中的实时射频干扰抑制：用于暂现源搜寻的两阶段方法
Real-Time RFI Mitigation in SPOTLIGHT: A Two-Stage Approach for Transient Searches
AI总结：
针对射电暂现源搜寻的RFI抑制难题，为uGMRT的SPOTLIGHT系统开发含VOLT与STRIPE的两阶段实时框架，使虚警率降98%、脉冲S/N提2.7倍，提升探测性能与可靠性。
AI中文摘要：
射频干扰（RFI）仍是限制现代射电暂现源巡天灵敏度与可靠性的主要挑战之一，尤其对快速射电暂现源的实时搜寻而言。SPOTLIGHT系统是工作在升级后的巨米波射电望远镜（uGMRT）上的共生式实时暂现源搜寻后端，稳健且计算高效的RFI抑制是其持续运行的关键。本文介绍为SPOTLIGHT开发的实时两阶段RFI抑制框架，包括在相关波束形成前运行的天线级电压滤波模块（VOLT），以及应用于波束形成后数据的统计RFI滤波框架——SPOTLIGHT时域RFI处理引擎（STRIPE）。这两种互补技术共同抑制了宽频谱的RFI：VOLT抑制宽带脉冲式干扰，STRIPE抑制窄带频谱受限的虚假信号，同时保持足够的计算效率以满足实时处理的严格要求。该框架通过常规GMRT共生观测、受控76颗脉冲星观测，并与PRESTO的rfifind工具进行基准测试来评估。已部署的系统使虚警率降低了98%；与未滤波数据相比，两阶段滤波后恢复的天体物理脉冲的信噪比（S/N）提升了2.7倍。这些改进提高了SPOTLIGHT的探测效率、灵敏度和运行可靠性，增强了其利用uGMRT发现射电暂现源的能力。
英文摘要：
Radio Frequency Interference (RFI) remains one of the primary challenges limiting the sensitivity and reliability of modern radio transient surveys, particularly for real-time searches of fast radio transients. The SPOTLIGHT system is a commensal real-time transient search backend operating at the upgraded Giant Metrewave Radio Telescope (uGMRT), where robust and computationally efficient RFI mitigation is essential for sustained operations. We present the real-time two-stage RFI mitigation framework developed for SPOTLIGHT, comprising an antenna-level voltage-filtering module (VOLT) operating prior to correlation beamforming and the SPOTLIGHT Time-domain RFI Processing Engine (STRIPE), a statistical RFI-filtering framework applied to beamformed data. Together, these complementary techniques mitigate a broad spectrum of RFI, ranging from broadband impulsive interference mitigated by VOLT to narrowband spectrally confined spurious signals mitigated by STRIPE, while remaining computationally efficient enough to satisfy the stringent requirements of real-time processing. The framework is evaluated using routine commensal GMRT observations, controlled 76 pulsar observations, and benchmarking against PRESTO's rfifind. The deployed system reduced the false detection rate by 98%. The recovered astrophysical pulses exhibit a 2.7x improvement in S/N after the two-stage filtering compared with the unfiltered data. These improvements enhance SPOTLIGHT's detection efficiency, sensitivity, and operational reliability, strengthening its capability to discover radio transients with the uGMRT.
