Ionosondes and Digisondes updated 12142002
Background, Theory, and Links
What Are They?
Ionosondes and Digisondes are devices that send a spectrum of radio wave pulses straight up (vertically incident to the ground).  They measure the length of time it takes for a reflection to be returned, the strength of the reflection, and how high of a frequency can be reflected.

 From these three data points (time, strength, frequency), the device can determine ionization density, altitude of the ionization, and potential Maximum Useable Frequency (MUF).

 Output from ionosondes and digisondes are displayed in the form of an "ionogram", or displayed in a tabular data format.

 Ionosondes have been used since early/mid 20th century, but there still is no widespread deployment.  Ionosondes and digisondes are primarily deployed and maintained by the US Air Force, a few universities, NOAA, and similar organizations in other countries. 

Links to more information on Ionosondes and Digisondes
How do you read the Digisonde Ionogram Plots? - Pat Dyer, WA5IYX has an example
Variables Explained - brief description of all of those variables (FoEs, FxEs, h'Es, etc)
NGDC Overview of Vertical Sounding  - NOAA's NGDC division 
Basic Ionosonde Theory
Background to Ionospheric Sounding
Case Study of an Ionosonde Move - lots of background information and details
Online Ionosonde and Digisonde Links

North America
AK - HAARP - Gakona, AK
AK - College, AK
CA - Pt Arguello (data rarely available)
FL - Eglin AFB
MA - Haystack
VA - Wallops Island, USAF
Greenland - Sondrestrom
Canada - Goose Bay, Labrador

Europe
Belgium - Dorbes
Greece - Athens
Italy - Rome
United Kingdom - Fairford AFB

Asia
Japan - 4 sites (w/ MPEG movie of ionograms)
China - Wuhan

Australia
Capital Territory - Canberra
Northern Territory - Darwin
Queensland - Brisbane
Queensland - Townsville
 


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