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1. A radio technosignature search towards Proxima Centauri resulting in a signal of interest

   https://doi.org/10.1038/s41550-021-01479-w  

   Smith, Shane ; Price, Danny C. ; Sheikh, Sofia Z. ; Czech, Daniel J. ; Croft, Steve ; DeBoer, David ; Gajjar, Vishal ; Isaacson, Howard ; Lacki, Brian C. ; Lebofsky, Matt ; et al ( October 2021 , Nature Astronomy)

   The detection of life beyond Earth is an ongoing scientific pursuit, with profound implications. One approach, known as the search for extraterrestrial intelligence (SETI), seeks to find engineered signals (‘technosignatures’) that indicate the existence of technologically capable life beyond Earth. Here, we report on the detection of a narrowband signal of interest at ~982 MHz, recorded during observations towards Proxima Centauri with the Parkes Murriyang radio telescope. This signal, BLC1, has characteristics broadly consistent with hypothesized technosignatures and is one of the most compelling candidates to date. Analysis of BLC1—which we ultimately attribute to being an unusual but locally generated form of interference—is provided in a companion paper. Nevertheless, our observations of Proxima Centauri are a particularly sensitive search for radio technosignatures towards a stellar target.
2. Iterative Space Time Block Equalizer for Single Carrier Systems with Receiver Nonlinearity

   https://doi.org/10.1109/WCNC51071.2022.9771797  

   Rahman, Talha Faizur ; Marojevic, Vuk ( April 2022 , 2022 IEEE Wireless Communications and Networking Conference (WCNC))

   Receiver nonlinearity gives rise to intermodulation products that are caused by two strong adjacent channel signals called blockers. The nonlinear distortion effects are significantly higher for multiple antenna wideband systems in dispersive environments because third order intermodulation products decreases the signal-to-noise ratio (SNR) at the output of the equalization process. This complicates the demodulation process and increases the bit error rate. This paper considers such nonlinear distortion in the context of space-time shift keying (STSK)-enabled wideband single-carrier systems and proposes an iterative space-time block equalization (ISTBE) framework for frequency domain equalization. We present our design of a practical ISTBE receiver based on the turbo principle and numerically demonstrate that it effectively removes the residual inter-symbol interference while suppressing high-power blockers and the in-band intermodulation distortion that they cause. The proposed system is thus suitable for simple wideband radio frequency front ends operating in the weak nonlinear region and enables adjacent channel spectrum coexistence with heterogeneous transmitters and receivers of different qualities.
3. The Breakthrough Listen Search for Intelligent Life: Technosignature Search of Transiting TESS Targets of Interest

   https://doi.org/10.3847/1538-3881/ac46c9  

   Franz, Noah ; Croft, Steve ; Siemion, Andrew P. V. ; Traas, Raffy ; Brzycki, Bryan ; Gajjar, Vishal ; Isaacson, Howard ; Lebofsky, Matthew ; MacMahon, David H. E. ; Price, Danny C. ; et al ( February 2022 , The Astronomical Journal)

   The Breakthrough Listen (BL) Initiative, as part of its larger mission, is performing the most thorough technosignature search of nearby stars. Additionally, BL is collaborating with scientists working on NASA’s Transiting Exoplanet Survey Satellite (TESS) to examine TESS Targets of Interest (TOIs) for technosignatures. Here, we present a 1–11 GHz radio technosignature search of 61 TESS TOIs that were in transit during their BL observation at the Robert C. Byrd Green Bank Telescope. We performed a narrowband Doppler drift search with a minimum S/N threshold of 10 across a drift rate range of ±4 Hz s⁻¹with a resolution of 3 Hz. We removed radio frequency interference by comparing signals across cadences of target sources. After interference removal, there are no remaining events in our survey, and therefore no technosignature signals of interest detected in this work. This null result implies that atL,S,C, andXbands, fewer than 52%, 20%, 16%, and 15%, respectively, of TESS TOIs possess a transmitter with an equivalent isotropic radiated power greater than a few times 10¹⁴W.
4. DeepVS: A Deep Learning Approach For RF-based Vital Signs Sensing

   https://doi.org/10.1145/3535508.3545554  

   Xie, Zongxing ; Wang, Hanrui ; Han, Song ; Schoenfeld, Elinor ; Ye, Fan ( January 2022 , In 13th ACM International Conference on Bioinformatics, Computational Biology and Health Informatics (BCB ’22))

   Vital signs (e.g., heart and respiratory rate) are indicative for health status assessment. Efforts have been made to extract vital signs using radio frequency (RF) techniques (e.g., Wi-Fi, FMCW, UWB), which offer a non-touch solution for continuous and ubiquitous monitoring without users’ cooperative efforts. While RF-based vital signs monitoring is user-friendly, its robustness faces two challenges. On the one hand, the RF signal is modulated by the periodic chest wall displacement due to heartbeat and breathing in a nonlinear manner. It is inherently hard to identify the fundamental heart and respiratory rates (HR and RR) in the presence of higher order harmonics of them and intermodulation between HR and RR, especially when they have overlapping frequency bands. On the other hand, the inadvertent body movements may disturb and distort the RF signal, overwhelming the vital signals, thus inhibiting the parameter estimation of the physiological movement (i.e., heartbeat and breathing). In this paper, we propose DeepVS, a deep learning approach that addresses the aforementioned challenges from the non-linearity and inadvertent movements for robust RF-based vital signs sensing in a unified manner. DeepVS combines 1D CNN and attention models to exploit local features and temporal correlations. Moreover, it leverages a two-stream schememore »to integrate features from both time and frequency domains. Additionally, DeepVS unifies the estimation of HR and RR with a multi-head structure, which only adds limited extra overhead (<1%) to the existing model, compared to doubling the overhead using two separate models for HR and RR respectively. Our experiments demonstrate that DeepVS achieves 80-percentile HR/RR errors of 7.4/4.9 beat/breaths per minute (bpm) on a challenging dataset, as compared to 11.8/7.3 bpm of a non-learning solution. Besides, an ablation study has been conducted to quantify the effectiveness of DeepVS.« less
5. Panoramic optical and near-infrared SETI instrument: overall specifications and science program

   https://doi.org/10.1117/12.2314268  

   Wright, Shelley A. ; Horowitz, Paul ; Maire, Jérôme ; Chaim-Weismann, Samuel A. ; Cosens, Maren ; Drake, Frank D. ; Howard, Andrew W. ; Marcy, Geoffrey W. ; Siemion, Andrew P. ; Stone, Remington P. ; et al ( July 2018 , Proceedings Volume 10702, Ground-based and Airborne Instrumentation for Astronomy VII; 107025)

   We present overall specifications and science goals for a new optical and near-infrared (350 - 1650 nm) instru- ment designed to greatly enlarge the current Search for Extraterrestrial Intelligence (SETI) phase space. The Pulsed All-sky Near-infrared Optical SETI (PANOSETI) observatory will be a dedicated SETI facility that aims to increase sky area searched, wavelengths covered, number of stellar systems observed, and duration of time monitored. This observatory will offer an “all-observable-sky” optical and wide-field near-infrared pulsed tech- nosignature and astrophysical transient search that is capable of surveying the entire northern hemisphere. The final implemented experiment will search for transient pulsed signals occurring between nanosecond to second time scales. The optical component will cover a solid angle 2.5 million times larger than current SETI targeted searches, while also increasing dwell time per source by a factor of 10,000. The PANOSETI instrument will be the first near-infrared wide-field SETI program ever conducted. The rapid technological advance of fast-response optical and near-infrared detector arrays (i.e., Multi-Pixel Photon Counting; MPPC) make this program now feasible. The PANOSETI instrument design uses innovative domes that house 100 Fresnel lenses, which will search concurrently over 8,000 square degrees for transient signals (see Maire et al. and Cosensmore »et al., this conference). In this paper, we describe the overall instrumental specifications and science objectives for PANOSETI.« less