Ionosonde
Encyclopedia
An ionosonde, or chirpsounder, is a special radar
for the examination of the ionosphere
. An ionosonde consists of:
The transmitter sweeps all or part of the HF frequency range, transmitting short pulses. These pulses are reflected at various layers of the ionosphere, at heights of 100–400 km, and their echos are received by the receiver and analyzed by the control system. The result is displayed in the form of an ionogram
, a graph of reflection height (actually time between transmission and reception of pulse) versus carrier frequency.
The basic ionosonde technology was invented in 1925 by Gregory Breit
and Merle A. Tuve and further developed in the late 1920s by a number of prominent physicists, including Edward Victor Appleton
. The term ionosphere
and hence, the etymology of its derivatives, was proposed by Robert Watson-Watt
.
An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
for the examination of the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...
. An ionosonde consists of:
- A high frequencyHigh frequencyHigh frequency radio frequencies are between 3 and 30 MHz. Also known as the decameter band or decameter wave as the wavelengths range from one to ten decameters . Frequencies immediately below HF are denoted Medium-frequency , and the next higher frequencies are known as Very high frequency...
(HF) transmitter, automatically tunable over a wide range. Typically the frequency coverage is 0.5–23 MHz or 1–40 MHz, though normally sweeps are confined to approximately 1.6–12 MHz. - A tracking HF receiver which can automatically track the frequency of the transmitter.
- An antenna with a suitable radiation pattern, which transmits well vertically upwards and is efficient over the whole frequency range used.
- Digital control and data analysis circuits.
The transmitter sweeps all or part of the HF frequency range, transmitting short pulses. These pulses are reflected at various layers of the ionosphere, at heights of 100–400 km, and their echos are received by the receiver and analyzed by the control system. The result is displayed in the form of an ionogram
Ionogram
An ionogram is a display of the data produced by an ionosonde. It is a graph of the virtual height of the ionosphere plotted against frequency. Ionograms are often converted into electron density profiles...
, a graph of reflection height (actually time between transmission and reception of pulse) versus carrier frequency.
The basic ionosonde technology was invented in 1925 by Gregory Breit
Gregory Breit
Gregory Breit was a Russian-born American physicist and professor at universities in New York, Wisconsin, Yale, and Buffalo...
and Merle A. Tuve and further developed in the late 1920s by a number of prominent physicists, including Edward Victor Appleton
Edward Victor Appleton
Sir Edward Victor Appleton, GBE, KCB, FRS was an English physicist.-Biography:Appleton was born in Bradford, West Yorkshire and educated at Hanson Grammar School. At the age of 18 he won a scholarship to St John's College, Cambridge...
. The term ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...
and hence, the etymology of its derivatives, was proposed by Robert Watson-Watt
Robert Watson-Watt
Sir Robert Alexander Watson-Watt, KCB, FRS, FRAeS is considered by many to be the "inventor of radar". Development of radar, initially nameless, was first started elsewhere but greatly expanded on 1 September 1936 when Watson-Watt became...
.
An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.
External links
- http://www.ngdc.noaa.gov/stp/iono/ionogram.html : NOAA Ionosonde portal to information and data services
- http://www.ngdc.noaa.gov/stp/IONO/Dynasonde/ : NOAA Dynasonde: Real-time Ionospheric Explorer by advanced and prototype analysis methods.
- http://aintel.bi.ehu.es/chirps-data/chirps.html
- http://ulcar.uml.edu/digisonde.html : Lowell Center for Atmospheric Research, MA, USA
- http://ulcar.uml.edu/stationlist.html : Ionosonde (partial) station list by location
- http://www.iono.noa.gr : National Observatoy of Athens, Greece
- http://www.sil.sk.ca/cadi.html : Canadian Advanced Digital Ionosonde (CADI)