Table · dataset · 2026

ISIS 2 Topside Sounder Ionograms

Listed in NASA Data Portal

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.

Description

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.

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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.

Topics

From keywords: Astronomy & Astrophysics · Earth & Environmental Science · Ocean & Atmospheric Science · Physics
Inferred from text: Video 75%

Provenance · 1 source records, 11 field assertions

Source	Key	Last seen	Raw
NASA Data Portal	be8ccce6-6946-48c5-86d3-38ffb68adf0d	11 d ago	JSON v1

Field	Assertion	Extractor	Evidence
concepts[field].local:field:astronomy	mapping · data nasa gov	connector:data_nasa_gov@1.0.0
concepts[field].local:field:earth-environmental	mapping · data nasa gov	connector:data_nasa_gov@1.0.0
concepts[field].local:field:ocean-atmospheric	mapping · data nasa gov	connector:data_nasa_gov@1.0.0
concepts[field].local:field:physics	mapping · data nasa gov	connector:data_nasa_gov@1.0.0
concepts[modality].local:modality:video	enrichment · data nasa gov	keyword-concept-rules@1.0.0	title+description (75%)
created_date	source · data nasa gov	connector:data_nasa_gov@1.0.0
description	source · data nasa gov	connector:data_nasa_gov@1.0.0	/notes
license_text	source · data nasa gov	connector:data_nasa_gov@1.0.0
publication_date	source · data nasa gov	connector:data_nasa_gov@1.0.0
title	source · data nasa gov	connector:data_nasa_gov@1.0.0	/title
updated_date	source · data nasa gov	connector:data_nasa_gov@1.0.0

ISIS 2 Topside Sounder Ionograms

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