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    • ISIS 2 Topside Sounder Ionograms

    Metadata Updated: March 13, 2026

    These ionograms were digitized from the original ISIS-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. Ionograms with this sample rate are designated as "full" ionograms because they have the full 3.75 km apparent-range resolution. The ionograms used for most analysis, and those available from CDAWeb, were produced by averaging every four samples of the sounder-receiver video amplitude output to yield an average value every 100 microseconds corresponding to an apparent-range resolution of 15 km. These ionogram files are referred to as "average" files with standard resolution. Each ionogram consists of a fixed-frequency and and a swept-frequency portion. The time resolution between ionograms is typically 14 or 22 seconds depending on the frequency sweep range.

    Access & Use Information

    Public: This dataset is intended for public access and use. License: See this page for license information.

    Downloads & Resources

    Dates

    Metadata Created Date March 13, 2026
    Metadata Updated Date March 13, 2026

    Metadata Source

    Harvested from NASA Data.json

    Other Data Resources

    Additional Metadata

    Resource Type Dataset
    Metadata Created Date March 13, 2026
    Metadata Updated Date March 13, 2026
    Publisher NASA Space Physics Data Facility (SPDF) Data Services
    Maintainer
    Identifier /SDE/SPASE_JSON/|c7b50e8914d7c33481152da4a1d41c7a
    Data Last Modified 2026-03-09
    Category Heliophysics
    Public Access Level public
    Bureau Code 026:00
    Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
    Schema Version https://project-open-data.cio.gov/v1.1/schema
    Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
    Harvest Object Id b739e245-d531-43f1-8f02-50b18ec441c6
    Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
    Harvest Source Title NASA Data.json
    License https://www.usa.gov/government-works
    Program Code 026:000
    Source Datajson Identifier True
    Source Hash 16c9afb24af46f7736baa66e1e45c2a40e5210905cca2950628ceabad60744e4
    Source Schema Version 1.1

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