{"@type": "dcat:Dataset", "accessLevel": "public", "bureauCode": ["026:00"], "contactPoint": {"@type": "vcard:Contact", "fn": "NASA Space Physics Data Facility", "hasEmail": "mailto:NASA-SPDF-Support@nasa.onmicrosoft.com"}, "description": "These ionograms were digitized from the original Alouette 2 7-track analog telemetry tapes using the facilities of the former Data Evaluation Laboratory at the NASA/GSFC. This data restoration project is headed by Dr. R.F. Benson (NASA/GSFC). Ionograms were digitized at the rate of 40,000 16-bit samples/sec. This sample rate is higher than the Nyquist frequency of 30 kHz. The sample frequency of 40 kHz provides a measurement every 25 microseconds corresponding to an apparent range (c*t/2) interval of 3.75 km. The ionograms consist of swept-frequency operation (there is no fixed-frequency operation as in ISIS-1 and ISIS-2). The time resolution between ionograms is typically 31 seconds.", "distribution": [{"@type": "dcat:Distribution", "downloadURL": "ftps://spdf.gsfc.nasa.gov/pub/data/alouette/topside_sounder/ionogram_cdaweb/alouette2/", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://cdaweb.gsfc.nasa.gov/sp_phys/", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://hpde.io/NASA/NumericalData/Alouette2/SFS/AverageIonogram/Fairbanks/PT31S", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://hpde.io/NASA/NumericalData/Alouette2/SFS/AverageIonogram/FalklandIslands/PT31S", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://hpde.io/NASA/NumericalData/Alouette2/SFS/AverageIonogram/Lima/PT31S", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://hpde.io/NASA/NumericalData/Alouette2/SFS/AverageIonogram/Quito/PT31S", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://hpde.io/NASA/NumericalData/Alouette2/SFS/AverageIonogram/Santiago/PT31S", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://hpde.io/NASA/NumericalData/Alouette2/SFS/AverageIonogram/Winkfield/PT31S", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1965-098A-01", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://spdf.gsfc.nasa.gov/isis/isis-status.html", "format": "HTML", "mediaType": "text/html"}, {"@type": "dcat:Distribution", "downloadURL": "https://spdf.gsfc.nasa.gov/pub/data/alouette/topside_sounder/ionogram_cdaweb/alouette2/", "format": "BIN", "mediaType": "application/octet-stream"}], "identifier": "/SDE/SPASE_JSON/|811dc3681e0c304b4bdc903e067eb241", "keyword": ["akr", "ducted-echoes", "fai", "field-aligned-irregularities", "ground-echoes", "ground-reflections", "ionospheric-echoes", "ionospheric-reflections", "plasma-resonance", "plasma-waves", "solar-type-iii-bursts", "spectrum-ionogram", "swept-frequency-sounder", "topside-ionosphere", "topside-sounder", "upper-hybrid-noise-band", "wave-scattering", "waves-active"], "license": "https://www.usa.gov/government-works", "modified": "2026-04-20", "programCode": ["026:000"], "publisher": {"@type": "org:Organization", "name": "NASA Space Physics Data Facility (SPDF) Data Services"}, "theme": ["Heliophysics"], "title": "Alouette-2 Topside Sounder Ionogram Data"}