{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/understanding-spectral-artefacts-in-ska-low","title":"Understanding spectral artefacts in SKA-LOW 21-cm cosmology experiments: the impact of cable reflections","arxiv_id":"2402.04008","date":"2024-02-06","proceeding":null,"authors":["Oscar Sage David O'Hara","Fred Dulwich","Eloy de Lera Acedo","Jiten Dhandha","Thomas Gessey-Jones","Dominic Anstey","Anastasia Fialkov"],"abstract":"The Cosmic Dawn was marked by the formation of the first stars, and preceded the Epoch of Reionization (EoR), when the Universe underwent a fundamental transformation caused by the radiation from these first stars and galaxies. Interferometric 21-cm experiments aim to probe redshifted neutral hydrogen signals from these periods, constraining the conditions of the early Universe. The SKA-Low instrument of the Square Kilometre Array (SKA) is envisaged to be the largest and most sensitive radio telescope at metre and centimetre wavelengths. The latest Aperture Array Verification Systems feature 7-m coaxial transmission lines connecting the low noise amplifiers to optical transmitters at the front of the analogue-receiving chain. An impedance mismatch between these components results in a partially reflected electromagnetic signal, introducing chromatic aberrations into the instrument bandpass. This causes power from the foreground signals to appear at higher delays, potentially contaminating the 'EoR window', a region in which the 21-cm signal should be detectable. We present an end-to-end simulation pipeline for SKA-Low using a composite sky model combining radio foregrounds from the Galactic and Extragalactic All-Sky MWA (GLEAM) Survey, Haslam $408\\,$MHz, and a 1.5-cGpc 21-cm brightness temperature cube generated with the 21cmSPACE simulator. We derive a model for the scattering parameters of a coaxial transmission line in terms of its specifications and bulk material properties. Assuming identical cables of length $\\leq 15.0\\,$m with impedance mismatch $\\leq 10\\, \\Omega$, the reflection is confined below the EoR window. However, we demonstrate that even a 0.1 per cent length tolerance introduces contamination with an absolute fractional difference of $\\sim 10$ per cent across all accessible k-modes.","url_abs":"https://arxiv.org/abs/2402.04008v2","url_pdf":"https://arxiv.org/pdf/2402.04008v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"understanding-spectral-artefacts-in-ska-low","repo_url":"https://github.com/ycliu23/Cambridge-SKA-SDC3-Foregrounds","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":{"status":"ok","spdx":"MIT"}}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":"https://syntology.ai/paper/2402.04008","atlas_url":"https://app.syntology.ai/?focus=2402.04008","mcp":{"get_harvested_code_for_paper":{"arxiv_id":"2402.04008"}},"developers":"https://syntology.ai/developers","read_at":"2026-09-25T09:33:49+00:00","read_at_is":"when the build read Syntology's graph, not when any sample ran","claim":"Per-sample execution status on synthesized fixtures; not a correctness claim about the paper. Samples come from repositories linked to the paper, official or community; repo_kind says which.","repos":[{"provenance":"external:paperswithcode_snapshot_2025-07-28","url":"https://github.com/ycliu23/Cambridge-SKA-SDC3-Foregrounds","reach":{"status":"ok","spdx":"MIT"}}],"summary":{"unverified":2},"by_repo_kind":{"listed":{"samples":2,"ran":0,"repositories":1}},"repo_kind_vocabulary":{"official":"The archive marks this repository official for the paper","named_in_paper":"The archive records that the paper mentions this repository; it is not marked official","listed":"In the archive's code links for this paper, not marked official and not recorded as mentioned in the paper","found_in_text":"Syntology found this repository in the paper's own text; whether it is the authors' implementation is not asserted","community":"Not in the archive's code links for this paper; a community repository Syntology harvested"},"n_pointer_only_for_licence":0,"samples":[{"code_sha256_prefix":"6862744dc265a80b","entry":"error_prop","repo":"ycliu23/Cambridge-SKA-SDC3-Foregrounds","repo_kind":"listed","path":"pipeline/cal_ps.py","file_url":"https://github.com/ycliu23/Cambridge-SKA-SDC3-Foregrounds/blob/HEAD/pipeline/cal_ps.py","link_basis":"harvester_set","language":"python","status":"unverified","verification_level":0,"contract_check":null,"metamorphic_tier":null,"behaviour_fingerprint":false,"licence":"MIT","inline_ok":true,"mcp_get_code":{"code_sha256":"6862744dc265a80b"}},{"code_sha256_prefix":"9a9729fbe4891041","entry":"ratio","repo":"ycliu23/Cambridge-SKA-SDC3-Foregrounds","repo_kind":"listed","path":"pipeline/cal_ps.py","file_url":"https://github.com/ycliu23/Cambridge-SKA-SDC3-Foregrounds/blob/HEAD/pipeline/cal_ps.py","link_basis":"harvester_set","language":"python","status":"unverified","verification_level":0,"contract_check":null,"metamorphic_tier":null,"behaviour_fingerprint":false,"licence":"MIT","inline_ok":true,"mcp_get_code":{"code_sha256":"9a9729fbe4891041"}}]},"arxiv_metadata":null,"syntology_extracted_results":null}