Pub Date : 2022-03-01DOI: 10.1142/S2251171722500088
K. Buch, R. Kale, K. Naik, Rahul Aragade, M. Muley, S. Kudale, Ajith Kumar
Electromagnetic radiation from human activities, known as man-made Radio Frequency Interference (RFI), adversely affects radio astronomy observations. In the vicinity of the Upgraded Giant Metrewave Radio Telescope (uGMRT) array, the sparking on power lines is the major cause of interference at observing frequencies less than 800 MHz. A real-time broadband RFI detection and filtering system is implemented as part of the uGMRT wideband signal processing backend to mitigate the effect of broadband RFI. Performance analysis techniques used for testing and commissioning the system for observations in the beamformer and correlator modes of the uGMRT are presented. The concept and implementation of recording simultaneous unfiltered and filtered data along with data analysis and interpretation is illustrated using an example. For the beamformer mode, spectrogram, single spectral channel, and its Fourier transform is used for performance analysis whereas, in the correlator mode, the cross-correlation function, closure phase, and visibilities from the simultaneously recorded unfiltered and filtered is carried out. These techniques are used for testing the performance of the broadband RFI filter and releasing it for uGMRT users.
{"title":"Performance Analysis Techniques for Real-time Broadband RFI Filtering System of uGMRT","authors":"K. Buch, R. Kale, K. Naik, Rahul Aragade, M. Muley, S. Kudale, Ajith Kumar","doi":"10.1142/S2251171722500088","DOIUrl":"https://doi.org/10.1142/S2251171722500088","url":null,"abstract":"Electromagnetic radiation from human activities, known as man-made Radio Frequency Interference (RFI), adversely affects radio astronomy observations. In the vicinity of the Upgraded Giant Metrewave Radio Telescope (uGMRT) array, the sparking on power lines is the major cause of interference at observing frequencies less than 800 MHz. A real-time broadband RFI detection and filtering system is implemented as part of the uGMRT wideband signal processing backend to mitigate the effect of broadband RFI. Performance analysis techniques used for testing and commissioning the system for observations in the beamformer and correlator modes of the uGMRT are presented. The concept and implementation of recording simultaneous unfiltered and filtered data along with data analysis and interpretation is illustrated using an example. For the beamformer mode, spectrogram, single spectral channel, and its Fourier transform is used for performance analysis whereas, in the correlator mode, the cross-correlation function, closure phase, and visibilities from the simultaneously recorded unfiltered and filtered is carried out. These techniques are used for testing the performance of the broadband RFI filter and releasing it for uGMRT users.","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48310753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-31DOI: 10.1142/s2251171722500064
A. Josaitis, D. DeBoer, E. de Lera Acedo
{"title":"SDR Pathfinder for Understanding Transient and Noise-level Interference in the Karoo (SPUTNIK)","authors":"A. Josaitis, D. DeBoer, E. de Lera Acedo","doi":"10.1142/s2251171722500064","DOIUrl":"https://doi.org/10.1142/s2251171722500064","url":null,"abstract":"","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49231850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-31DOI: 10.1142/s2251171722500052
Nishant Neeraj Gadey
{"title":"Mersenne Beam-compressor with Field-flattener optics as Main Telescope design for Extremely Large Telescopes and Telescope Arrays","authors":"Nishant Neeraj Gadey","doi":"10.1142/s2251171722500052","DOIUrl":"https://doi.org/10.1142/s2251171722500052","url":null,"abstract":"","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42291947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-27DOI: 10.1142/S2251171722500167
Kalyani B. Bhopi, W. Tyndall, P. Sanghavi, K. Bandura, L. Newburgh, Jason Gallichio
Foreground mitigation is critical to all next-generation radio interferometers that target cosmology using the redshifted neutral hydrogen 21 cm emission line. Attempts to remove this foreground emission have led to new analysis techniques as well as new developments in hardware specifically dedicated to instrument beam and gain calibration, including stabilized signal injection into the interferometric array and drone-based platforms for beam mapping. The radio calibration sources currently used in the literature are broad-band incoherent sources that can only be detected as excess power and with no direct sensitivity to phase information. In this paper, we describe a digital radio source which uses Global Positioning Satellite (GPS) derived time stamps to form a deterministic signal that can be broadcast from an aerial platform. A copy of this source can be deployed locally at the instrument correlator such that the received signal from the aerial platform can be correlated with the local copy, and the resulting correlation can be measured in both amplitude and phase for each interferometric element. We define the requirements for such a source, describe an initial implementation and verification of this source using commercial Software Defined Radio boards, and present beam map slices from antenna range measurements using the commercial boards. We found that the commercial board did not meet all requirements, so we also suggest future directions using a more sophisticated chipset.
{"title":"A Digital Calibration Source for 21cm Cosmology Telescopes","authors":"Kalyani B. Bhopi, W. Tyndall, P. Sanghavi, K. Bandura, L. Newburgh, Jason Gallichio","doi":"10.1142/S2251171722500167","DOIUrl":"https://doi.org/10.1142/S2251171722500167","url":null,"abstract":"Foreground mitigation is critical to all next-generation radio interferometers that target cosmology using the redshifted neutral hydrogen 21 cm emission line. Attempts to remove this foreground emission have led to new analysis techniques as well as new developments in hardware specifically dedicated to instrument beam and gain calibration, including stabilized signal injection into the interferometric array and drone-based platforms for beam mapping. The radio calibration sources currently used in the literature are broad-band incoherent sources that can only be detected as excess power and with no direct sensitivity to phase information. In this paper, we describe a digital radio source which uses Global Positioning Satellite (GPS) derived time stamps to form a deterministic signal that can be broadcast from an aerial platform. A copy of this source can be deployed locally at the instrument correlator such that the received signal from the aerial platform can be correlated with the local copy, and the resulting correlation can be measured in both amplitude and phase for each interferometric element. We define the requirements for such a source, describe an initial implementation and verification of this source using commercial Software Defined Radio boards, and present beam map slices from antenna range measurements using the commercial boards. We found that the commercial board did not meet all requirements, so we also suggest future directions using a more sophisticated chipset.","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2022-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49382485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-26DOI: 10.1142/S225117172150015X
C. Dilullo, J. Dowell, G. Taylor
We present recent improvements to the search for the global Cosmic Dawn signature using the Long Wavelength Array station located on the Sevilleta National Wildlife Refuge in New Mexico, USA (LWA–SV). These improvements are both in the methodology of the experiment and the hardware of the station. An improved observing strategy along with more sophisticated temperature calibration and foreground modelling schemes have led to improved residual RMS limits. A large improvement over previous work using LWA–SV is the use of a novel achromatic beamforming technique which has been developed for LWA–SV. We present results from an observing campaign which contains 29 days of observations between March 10, 2021 and April 1
{"title":"Improvements to the Search for Cosmic Dawn Using the Long Wavelength Array","authors":"C. Dilullo, J. Dowell, G. Taylor","doi":"10.1142/S225117172150015X","DOIUrl":"https://doi.org/10.1142/S225117172150015X","url":null,"abstract":"We present recent improvements to the search for the global Cosmic Dawn signature using the Long Wavelength Array station located on the Sevilleta National Wildlife Refuge in New Mexico, USA (LWA–SV). These improvements are both in the methodology of the experiment and the hardware of the station. An improved observing strategy along with more sophisticated temperature calibration and foreground modelling schemes have led to improved residual RMS limits. A large improvement over previous work using LWA–SV is the use of a novel achromatic beamforming technique which has been developed for LWA–SV. We present results from an observing campaign which contains 29 days of observations between March 10, 2021 and April 1","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2021-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45341931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-24DOI: 10.1142/S2251171722500076
Pusen Wang, Chih-Yun Chen, Hsiang-Chieh Hsu, Mu-Hsin Chang, W. Liu, H. Fang, Ting-Chou Wu, Wen-hao Chen, Chin Cheng Tsai, A. Chen, Yi Yang
The development of CubeSats and more frequent launch chances of sounding rockets are a total game changer to the space program, and it allows us to build space instruments that are technologically feasible and a ff ordable. Therefore, it gives us a good opportunity to build a small cosmic-ray detector which has capabilities to measure the flux, direction, and even energy of cosmic rays at an altitude above the limitation of balloon experiments, and it may open a new door for building a constellation of detectors to study cosmic-ray physics. Compact Scintillator Array Detector (ComSAD) is a funded sounding rocket mission of Taiwan’s National Space Organization. In this paper, we present the concept, design, and performance of ComSAD which is also suitable for future CubeSat missions.
{"title":"Compact Scintillator Array Detector (ComSAD) for sounding rocket and CubeSat missions","authors":"Pusen Wang, Chih-Yun Chen, Hsiang-Chieh Hsu, Mu-Hsin Chang, W. Liu, H. Fang, Ting-Chou Wu, Wen-hao Chen, Chin Cheng Tsai, A. Chen, Yi Yang","doi":"10.1142/S2251171722500076","DOIUrl":"https://doi.org/10.1142/S2251171722500076","url":null,"abstract":"The development of CubeSats and more frequent launch chances of sounding rockets are a total game changer to the space program, and it allows us to build space instruments that are technologically feasible and a ff ordable. Therefore, it gives us a good opportunity to build a small cosmic-ray detector which has capabilities to measure the flux, direction, and even energy of cosmic rays at an altitude above the limitation of balloon experiments, and it may open a new door for building a constellation of detectors to study cosmic-ray physics. Compact Scintillator Array Detector (ComSAD) is a funded sounding rocket mission of Taiwan’s National Space Organization. In this paper, we present the concept, design, and performance of ComSAD which is also suitable for future CubeSat missions.","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2021-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42630136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-09DOI: 10.1142/s2251171721500148
J. Bunton, G. Comoretto, I. Morrison, D. C. Shaff, A. Deller, W. van Straten, A. Jameson
{"title":"Performance of Oversampled Polyphase Filterbank Inversion Via Fourier Transform: Continuous Signals","authors":"J. Bunton, G. Comoretto, I. Morrison, D. C. Shaff, A. Deller, W. van Straten, A. Jameson","doi":"10.1142/s2251171721500148","DOIUrl":"https://doi.org/10.1142/s2251171721500148","url":null,"abstract":"","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2021-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47873657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-01DOI: 10.1142/S2251171721500136
Weiwei Chen, E. Barr, R. Karuppusamy, Michael Kramer, B. Stappers
Large-scale beamforming with radio interferometers has the potential to revolutionize the science done with pulsars and fast radio bursts by improving the survey efficiency for these sources. We describe a wide-field beamformer for the MeerKAT radio telescope and outline strategies to optimally design such surveys. A software implementation of these techniques, Mosaic is introduced and its application in the MeerKAT telescope is presented. We show initial results using the beamformer by observing a globular cluster to track several pulsars simultaneously and demonstrate the source localization capability of this observation.
{"title":"Wide field Beamformed Observation with MeerKAT","authors":"Weiwei Chen, E. Barr, R. Karuppusamy, Michael Kramer, B. Stappers","doi":"10.1142/S2251171721500136","DOIUrl":"https://doi.org/10.1142/S2251171721500136","url":null,"abstract":"Large-scale beamforming with radio interferometers has the potential to revolutionize the science done with pulsars and fast radio bursts by improving the survey efficiency for these sources. We describe a wide-field beamformer for the MeerKAT radio telescope and outline strategies to optimally design such surveys. A software implementation of these techniques, Mosaic is introduced and its application in the MeerKAT telescope is presented. We show initial results using the beamformer by observing a globular cluster to track several pulsars simultaneously and demonstrate the source localization capability of this observation.","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43994689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-21DOI: 10.1142/s2251171722500015
J. Cumner, E. Acedo, D. Villiers, D. Anstey, C. Kolitsidas, B. Gurdon, N. Fagnoni, P. Alexander, G. Bernardi, H. Bevins, S. Carey, J. Cavillot, Riccardo Chiello, C. Craeye, W. Croukamp, J. Ely, A. Fialkov, T. Gessey-Jones, Q. Gueuning, Will Handley, R. Hills, A. Josaitis, G. Kulkarni, A. Magro, R. Maiolino, P. Meerburg, S. Mittal, J. Pritchard, E. Puchwein, N. Razavi-Ghods, I. Roque, A. Saxena, K. Scheutwinkel, E. Shen, P. Sims, O. Smirnov, M. Spinelli, K. Zarb-Adami
Following the reported detection of an absorption pro¯le associated with the 21 cm sky-averaged signal from the Cosmic Dawn by the EDGES experiment in 2018, a number of experiments have been set up to verify this result. This paper discusses the design process used for global 21 cm experiments, focusing speci¯cally on the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH). This experiment will seek to understand and compensate for systematic errors present using detailed modeling and characteri-zation of the instrumentation. Detailed quantitative ¯gures of merit and numerical modeling are used to assist the design process of the REACH dipole antenna (one of the two antenna designs for REACH Phase I). This design process produced a 2.5:1 frequency bandwidth dipole. The aim of this design was to balance spectral smoothness and low impedance re°ections with the ability to describe and understand the antenna response to the sky signal to inform the critically important calibration during observation and data analysis.
{"title":"Radio antenna design for sky-averaged 21 cm cosmology experiments: the REACH case","authors":"J. Cumner, E. Acedo, D. Villiers, D. Anstey, C. Kolitsidas, B. Gurdon, N. Fagnoni, P. Alexander, G. Bernardi, H. Bevins, S. Carey, J. Cavillot, Riccardo Chiello, C. Craeye, W. Croukamp, J. Ely, A. Fialkov, T. Gessey-Jones, Q. Gueuning, Will Handley, R. Hills, A. Josaitis, G. Kulkarni, A. Magro, R. Maiolino, P. Meerburg, S. Mittal, J. Pritchard, E. Puchwein, N. Razavi-Ghods, I. Roque, A. Saxena, K. Scheutwinkel, E. Shen, P. Sims, O. Smirnov, M. Spinelli, K. Zarb-Adami","doi":"10.1142/s2251171722500015","DOIUrl":"https://doi.org/10.1142/s2251171722500015","url":null,"abstract":"Following the reported detection of an absorption pro¯le associated with the 21 cm sky-averaged signal from the Cosmic Dawn by the EDGES experiment in 2018, a number of experiments have been set up to verify this result. This paper discusses the design process used for global 21 cm experiments, focusing speci¯cally on the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH). This experiment will seek to understand and compensate for systematic errors present using detailed modeling and characteri-zation of the instrumentation. Detailed quantitative ¯gures of merit and numerical modeling are used to assist the design process of the REACH dipole antenna (one of the two antenna designs for REACH Phase I). This design process produced a 2.5:1 frequency bandwidth dipole. The aim of this design was to balance spectral smoothness and low impedance re°ections with the ability to describe and understand the antenna response to the sky signal to inform the critically important calibration during observation and data analysis.","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2021-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44736978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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