Towards Real-Time Impulsive RFI Mitigation for Radio Telescopes

2016 ◽  
Vol 05 (04) ◽  
pp. 1641018 ◽  
Author(s):  
Kaushal D. Buch ◽  
Shruti Bhatporia ◽  
Yashwant Gupta ◽  
Swapnil Nalawade ◽  
Aditya Chowdhury ◽  
...  
Keyword(s):  
Real Time ◽  
Signal To Noise Ratio ◽  
Wide Band ◽  
Radio Frequency Interference ◽  
Radio Telescopes ◽  
Signal To Noise ◽  
Absolute Deviation ◽  
Time Threshold ◽  
Filtering Technique ◽  
Estimation And Filtering

Radio Frequency Interference (RFI) is a growing concern for contemporary radio telescopes. This paper describes techniques for real-time threshold-based detection and filtering of broadband and narrowband RFI for the correlator and beamformer chains of a telescope back-end, with specific applications to the upgraded Giant Meterwave Radio Telescope (uGMRT). The Median Absolute Deviation (MAD) estimator is used for robust estimation of dispersion of the received signal in temporal and spectral domains. Results from the tests carried out for the GMRT wide-band backend (GWB) using this technique show 10 dB improvement in the signal-to-noise ratio. MAD-based estimation and filtering was also found to be useful for filtering beamformer data. The RFI filtering technique demonstrated in this paper will find applications in other radio telescopes as well as receivers for digital communication and passive radiometry.

Real-Time Implementation of MAD-Based RFI Excision on FPGA

2019 ◽  
Vol 08 (01) ◽  
pp. 1940006 ◽  
Author(s):  
Kaushal D. Buch ◽  
Kishor Naik ◽  
Swapnil Nalawade ◽  
Shruti Bhatporia ◽  
Yashwant Gupta ◽  
...  
Keyword(s):  
Real Time ◽  
Field Programmable Gate Array ◽  
Signal To Noise Ratio ◽  
Radio Frequency Interference ◽  
Challenging Problem ◽  
Signal To Noise ◽  
Absolute Deviation ◽  
Field Programmable ◽  
Wideband Radio ◽  
Robust Variant

Radio Frequency Interference (RFI) excision in wideband radio telescope receivers is gaining significance due to increasing levels of manmade RFI and operation outside the protected radio astronomy bands. The effect of RFI on astronomical data can be significantly reduced through real-time excision. In this paper, Median Absolute Deviation (MAD) is used for excising signals corrupted by strong impulsive interference. MAD estimation requires recursive median calculation which is a computationally challenging problem for real-time excision. This challenge is addressed by implementation of a histogram-based technique for MAD computation. The architecture is developed and optimized for Field Programmable Gate Array (FPGA) implementation. The design of a more robust variant of MAD called Median-of-MAD (MoM) is described. The architecture of MAD and MoM techniques and subsequent optimization allows for four RFI excision blocks on a single Xilinx Virtex-5 FPGA. These techniques have been tested on the GMRT wideband backend (GWB) processing a maximum of 400[Formula: see text]MHz bandwidth and the results show significant improvement in the signal-to-noise ratio (SNR).

scholarly journals QPSK Demodulator Based on Wideband Acquisition System

2020 ◽  
Vol 9 (3) ◽  
pp. 755-760
Keyword(s):  
Design Process ◽  
Input Signal ◽  
Signal To Noise Ratio ◽  
Wide Band ◽  
Phase Lock Loop ◽  
Base Station ◽  
Acquisition System ◽  
Signal To Noise ◽  
Phase Lock ◽  
Low Input

The paper describes the design of the QPSK demodulator based satellite base station. The most important requirement of the design process is to have wide band acquisition range of 100 kHz under narrow Phase Lock Loop (PLL) bandwidth and low input Signal to Noise Ratio (SNR). The efficiency of the technique is verified with extensive simulations in MATLAB.

Development and Characterization of an Electrocochleography-Guided Robotics-Assisted Cochlear Implant Array Insertion System

2021 ◽  
pp. 019459982110492
Author(s):  
Allan M. Henslee ◽  
Christopher R. Kaufmann ◽  
Matt D. Andrick ◽  
Parker T. Reineke ◽  
Viral D. Tejani ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Real Time ◽  
Signal To Noise Ratio ◽  
Electrode Array ◽  
High Signal ◽  
Animal Testing ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Hearing Outcomes

Objective Electrocochleography (ECochG) is increasingly being used during cochlear implant (CI) surgery to detect and mitigate insertion-related intracochlear trauma, where a drop in ECochG signal has been shown to correlate with a decline in hearing outcomes. In this study, an ECochG-guided robotics-assisted CI insertion system was developed and characterized that provides controlled and consistent electrode array insertions while monitoring and adapting to real-time ECochG signals. Study Design Experimental research. Setting A research laboratory and animal testing facility. Methods A proof-of-concept benchtop study evaluated the ability of the system to detect simulated ECochG signal changes and robotically adapt the insertion. Additionally, the ECochG-guided insertion system was evaluated in a pilot in vivo sheep study to characterize the signal-to-noise ratio and amplitude of ECochG recordings during robotics-assisted insertions. The system comprises an electrode array insertion drive unit, an extracochlear recording electrode module, and a control console that interfaces with both components and the surgeon. Results The system exhibited a microvolt signal resolution and a response time <100 milliseconds after signal change detection, indicating that the system can detect changes and respond faster than a human. Additionally, animal results demonstrated that the system was capable of recording ECochG signals with a high signal-to-noise ratio and sufficient amplitude. Conclusion An ECochG-guided robotics-assisted CI insertion system can detect real-time drops in ECochG signals during electrode array insertions and immediately alter the insertion motion. The system may provide a surgeon the means to monitor and reduce CI insertion–related trauma beyond manual insertion techniques for improved CI hearing outcomes.

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