消除移动源引起的射频干扰的基准天线技术
Reference antenna techniques for canceling radio frequency interference due to moving sources
摘要：
我们调查的射频干扰（RFI）信号的特性，可以影响一些干扰缓解算法的切除潜力。所考虑的技术是那些修改信号从辅助参考天线模型和取消干扰的天文观测。这些技术可以应用于时域，其中RFI电压被建模并从天文信号路径中减去（自适应噪声消除），或者它们可以应用于频域中的自相关和互相关电压谱（后相关消除）。对于理想的接收机和一个单一的，统计上稳定的干扰信号，预相关和后相关滤波器可以导致从观察干扰的完全消除。后相关方法的优点是可以应用于几十或几百毫秒的时间尺度，而不是几十或几百纳秒的时间尺度。然而，如果RFI发射机位置改变，这可能是一个缺点，因为将天文学和参考信号路径中的干扰功率联系起来的互相关功率测量可能去相关。如果去相关不太严重，则可以以噪声增加为代价来允许去相关。时域自适应消除器允许稍微改变其内部系数并适应积分期间的相位变化，这意味着它们避免了去相关问题。然而，适应的自由度也导致噪声增加。在本文中，这两种类型的消除器切除来自移动源的干扰的能力进行了比较。消除器在观测数据和模拟数据上都表现良好，完全消除。
英文摘要：
We investigate characteristics of radio frequency interference (RFI) signals that can affect the excision potential of some interference mitigation algorithms. The techniques considered are those that modify signals from auxiliary reference antennas to model and cancel interference from an astronomical observation. These techniques can be applied in the time domain, where the RFI voltage is modeled and subtracted from the astronomy signal path (adaptive noise canceling), or they can be applied to the autocorrelated and cross-correlated voltage spectra in the frequency domain (postcorrelation canceling). For ideal receivers and a single, statistically stationary interfering signal, both precorrelation and postcorrelation filters can result in complete cancellation of the interference from the observation. The postcorrelation method has the advantage of being applied on tens or hundreds of millisecond timescales rather than tens or hundreds of nanosecond timescales. However, this can be a disadvantage if the RFI transmitter location is changing, since the cross-correlated power measurements which link the interference power in the astronomy and reference signal paths can decorrelate. If the decorrelation is not too severe, it can be allowed for, at the expense of a noise increase. The time domain adaptive cancelers are allowed to slightly vary their internal coefficients and adapt to changing phases during the integrations, which means that they avoid the decorrelation problem. However, the freedom to adapt also results in a noise increase. In this paper the ability of both types of cancelers to excise interference originating from a moving source is compared. The cancelers perform well on both observed and simulated data, giving complete cancellation.
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