{"paper":{"title":"Systematic Spectral Distortion from Digital Whitening in Radio Telescopes and Implications for 21 cm Cosmology","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"Digital whitening of radio signals followed by re-quantization introduces systematic spectral distortions at levels problematic for 21 cm cosmology.","cross_cats":["astro-ph.CO"],"primary_cat":"astro-ph.IM","authors_text":"Daniel C. Jacobs, Gregg Hallinan, Larry R. D'Addario, Ruby Byrne","submitted_at":"2026-05-06T22:24:31Z","abstract_excerpt":"We identify a systematic distortion of the gain-vs.-frequency function of radio telescopes caused by digital flattening (\"whitening\") of the signal's spectrum followed by re-quantization, a common pair of processes in the signal processing of modern telescopes. Wide-bandwidth telescopes often have a large variation of signal power over frequency. Flattening of the spectrum allows samples of the channelized signal to be represented in a small number of bits, allowing efficient downstream processing. However, we show that this produces subtle systematic error in the measured spectra. We explore "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Although the effect can be small so that it has heretofore been unrecognized, we demonstrate that it produces distortion of the spectrum at a level that is problematic for some science, in particular 21 cm cosmology.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the observed distortion in OVRO-LWA data and the semi-analytic simulations arise specifically and solely from the whitening-plus-re-quantization sequence rather than from other unmodeled instrumental or environmental effects.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Digital spectrum whitening followed by re-quantization introduces a previously unrecognized systematic distortion in the gain-versus-frequency response of radio telescopes, reaching levels problematic for 21 cm cosmology.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Digital whitening of radio signals followed by re-quantization introduces systematic spectral distortions at levels problematic for 21 cm cosmology.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"5d925ba4cb6febc7ca0426de28208d30c56750e69b844fce4cdbba2d262b11b4"},"source":{"id":"2605.05489","kind":"arxiv","version":2},"verdict":{"id":"67958db1-b0ea-40df-939c-d9de5ce64123","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-08T15:35:47.610647Z","strongest_claim":"Although the effect can be small so that it has heretofore been unrecognized, we demonstrate that it produces distortion of the spectrum at a level that is problematic for some science, in particular 21 cm cosmology.","one_line_summary":"Digital spectrum whitening followed by re-quantization introduces a previously unrecognized systematic distortion in the gain-versus-frequency response of radio telescopes, reaching levels problematic for 21 cm cosmology.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the observed distortion in OVRO-LWA data and the semi-analytic simulations arise specifically and solely from the whitening-plus-re-quantization sequence rather than from other unmodeled instrumental or environmental effects.","pith_extraction_headline":"Digital whitening of radio signals followed by re-quantization introduces systematic spectral distortions at levels problematic for 21 cm cosmology."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2605.05489/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"ai_meta_artifact","ran_at":"2026-05-20T09:40:48.948838Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_title_agreement","ran_at":"2026-05-19T20:31:19.583466Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_compliance","ran_at":"2026-05-19T13:30:46.447379Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"1aa97978184b3ff9de4bcad55657e1506f3039495e26b9fa95ca468fc29f36cc"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}