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Spectral polarization filtering in the range–Doppler domain plays an important role in weather radar clutter mitigation. However, when ground clutter and precipitation overlap, these methods tend to filter out clutter-contaminated precipitation, leading to estimation errors. To address this problem, this article proposes a ground clutter and noise mitigation method based on range–Doppler spectral processing for polarimetric Doppler weather radars. The proposed method can filter out clutter and noise and retain precipitation overlapped with clutter by analyzing the property differences between precipitation and clutter and noise in the range–Doppler spectrogram. Specifically, due to the spatial continuity of precipitation in the range–Doppler domain, the spectral moments (e.g., velocity and spectral width) are also continuous. In addition, polynomial fitting is used to compensate for the missing spectral moments, and the missing precipitation is recovered by Gaussian fitting using the computed spectral moments. The results demonstrate performance improvements after applying the proposed method to radar data collected by Chinese operational weather radars. The proposed method is compared with several other algorithms, and the comparison results show that the proposed method performs best in clutter and noise suppression and precipitation retention performance.

Abstract Single‐unit (SU) recording in nonhuman primates (NHPs) is indispensible in the quest of how the brain works, yet electrodes currently used for the NHP brain are limited in signal longevity, stability, and spatial coverage. Using new structural materials, microfabrication, and penetration techniques, we develop a mechanically robust ultraflexible, 1 µm thin electrode array (MERF) that enables pial penetration and high‐density, large‐scale, and chronic recording of neurons along both vertical and horizontal cortical axes in the nonhuman primate brain. Recording from three monkeys yields 2,913 SUs from 1,065 functional recording channels (up to 240 days), with some SUs tracked for up to 2 months. Recording from the primary visual cortex (V1) reveals that neurons with similar orientation preferences for visual stimuli exhibited higher spike correlation. Furthermore, simultaneously recorded neurons in different cortical layers of the primary motor cortex (M1) show preferential firing for hand movements of different directions. Finally, it is shown that a linear decoder trained with neuronal spiking activity across M1 layers during monkey's hand movements can be used to achieve on‐line control of cursor movement. Thus, the MERF electrode array offers a new tool for basic neuroscience studies and brain–machine interface (BMI) applications in the primate brain.

This paper proposes an adaptive filtering method called the Adaptive Moving spectral Depolarization Ratio (AMsDR) filter to mitigate the clutter for dual-polarization weather radar based on Jensen-Shannon divergence principle. Specifically, the spectral depolarization ratio in the range-Doppler domain is the main variable distinguishing precipitation from clutter. The AMsDR filter can remove the clutter and noise and retain precipitation based on the difference of the spectral polarization feature and the spectral continuity of precipitation and clutter. The AMsDR filter can adaptively select the filter threshold depending on the echo difference between precipitation and clutter in different azimuths. Thus, the performance of the proposed filter is better than that of the current methods.

To mitigate Radio Frequency Interference (RFI) for polarimetric Doppler weather radars, this paper proposes to use spectral polarimetric filters. Polarimetric weather radars can be divided into two basic categories: Simultaneously Transmitting and Simultaneously Receiving (STSR) and Alternately Transmitting and Simultaneously Receiving (ATSR). First, the real RFI measurements from an operational C-band STSR weather radar help characterize the temporal, spectral and polarimetric features of RFI. Then, RFI is simulated in an X-band ATSR radar to quantify the performances of spectral polarimetric filters. Overall, spectral polarimetric filters can keep the precipitation and remove RFI in an ATSR radar. Finally, the data division method is put forward for STSR radars by mimicking the ATSR measurements. Good performance in RFI mitigation is also verified by using the same spectral polarimetric filters.