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Photographic Records Showing the Variations of the Virtual Height of Reflection as a Function of the Radio Frequency

Metadata Updated: November 12, 2020

The standard (analog) ionosonde produces photographic records known as ionograms, which show the variations of the virtual height of reflection as a function of the radio frequency. The frequency band normally used is from about 1 MHz to about 20 MHz though some ionosondes operate down to about 0.20 MHz and up to 30 MHz. The ionograms actually show the time of travel of the pulse signal from the transmitter to the ionosphere and back to the receiver. A given station typically generates a sweep-frequency ionogram in about two minutes. Normally four ionograms are taken per hour, one at each quarter hour. As of May 1994, there are approximately 16,140 rolls of ionogram film at our Data Center. Most of these photographic records (ionograms) were recorded on 35mm film, but there are some 16mm ionogram film. One month of 35mm ionograms averages about 800 feet of film. These rolls of film are kept off site but can be retrieved when needed. If you would like to study specific ionograms, researchers are welcome at the NOAA National Centers for Environmental Information (formerly National Geophysical Data Center), but are requested to give adequate advance notice of their visit so that appropriate arrangements may be made for their work space at the Data Center. Some ionograms were digitized and are stored in TIF G4 format.

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License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Date September 18, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 1957 (publication)
Frequency Of Update continual

Metadata Source

Harvested from NGDC STP Ionosonde

Additional Metadata

Resource Type Dataset
Metadata Date September 18, 2015
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) January 1, 1957 (publication)
Responsible Party Unknown
Contact Email
Guid gov.noaa.ngdc.stp.ionosonde:G00551
Access Constraints Use Constraints: None, Access Constraints: No Constraints
Bbox East Long 180.000000
Bbox North Lat 90.000000
Bbox South Lat -90.000000
Bbox West Long -180.000000
Coupled Resource
Frequency Of Update continual
Harvest Object Id 80a14611-9eff-461e-b108-dbf667066d0f
Harvest Source Id 9e78f6bc-78d6-4bc1-b987-e86ecff1598d
Harvest Source Title NGDC STP Ionosonde
Licence While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
Metadata Language eng; USA
Metadata Type geospatial
Progress underDevelopment
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 1944-03-01

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