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{{Short description|Radar for the ionosphere}}
{{merge from|Chirp transmitter|discuss=Talk:Ionosonde#Merger proposal|date=December 2015}}
[[File:Ionogramme.png|250px|thumb|right|Typical [[ionogram]] indicating foF2 of approximately 5.45 MHz.]]
[[File:Ionogramme.png|250px|thumb|right|Typical [[ionogram]] indicating an [[F2 layer]] critical frequency (foF2) of approximately 5.45 MHz.]]
[[File:Canadian Advanced Digital Ionosonde.jpg|thumb|right|An example of an ionosonde system displaying an ionogram]]
[[File:Canadian Advanced Digital Ionosonde.jpg|thumb|right|An example of an ionosonde system displaying an ionogram]]
An '''ionosonde''', or '''chirpsounder''', is a special [[radar]] for the examination of the [[ionosphere]]. The basic ionosonde technology was invented in 1925 by [[Gregory Breit]] and [[Merle A. Tuve]] <ref name="Judd1988">{{cite book|publisher=Heinemann|title=Radio Wave Propagation (HF Bands)|author=F.C. Judd, G2BCX|date=1987|location=London|isbn=0-434-90926-2|pages=12–20, 27–37}}</ref> 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''', or '''chirpsounder''', is a special [[radar]] for the examination of the [[ionosphere]]. The basic ionosonde technology was invented in 1925 by [[Gregory Breit]] and [[Merle A. Tuve]]<ref name="Judd1988">{{cite book|publisher=Heinemann|title=Radio Wave Propagation (HF Bands)|author=F.C. Judd, G2BCX|date=1987|location=London|isbn=978-0-434-90926-1|pages=12–20, 27–37}}</ref> 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]].


==Components==
An ionosonde consists of:
An ionosonde consists of:


* A [high frequency] (HF) transmitter, automatically tunable over a wide range. Typically the frequency coverage is 0.5–23&nbsp;MHz or 1–40&nbsp;MHz, though normally sweeps are confined to approximately 1.6–12&nbsp;MHz.
* A [[high frequency]] (HF) radio transmitter, automatically tunable over a wide range. Typically the frequency coverage is 0.5–23&nbsp;MHz or 1–40&nbsp;MHz, though normally sweeps are confined to approximately 1.6–12&nbsp;MHz.
* A tracking HF receiver which can automatically track the frequency of the transmitter.
* 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.
* 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.
* 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&nbsp;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 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&nbsp;km (60 to 250 miles), 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]].


An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.
An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.

==Ionogram==
[[File:HAARP ionogram.png|border|Ionogram produced by a ''Lowell Digisonde'', with explanations for various indications and recordings.]]

An '''ionogram''' is a display of the data produced by an ionosonde; technically speaking one may call the data used to make the display as the ionogram but often this is simply implied. It is a graph of the virtual height of the ionosphere plotted against frequency. Ionograms are often converted into electron density profiles. Data from ionograms may be used to measure changes in the Earth's [[ionosphere]] due to [[space weather]] events.

Note that in the ionogram above the legend can be more clearly understood as having "Vx-" and "Vx+" to replace respectively "X-" and "X+". These refer to the vertical reflection of the eXtraordinary kind. "Vo-" and "Vo+" refer to the Ordinary reflection. An Ordinarily reflected wave is the one that behaves as though there were no geomagnetic field.

ARTIST is the software program used to "scale" (deduce or calculate) the characteristic parameter values shown in the table on the left. The version shown here is "5", which is the latest as of March 2022. Ion2Png is the software program used to create the ionogram image.

==Chirp transmitter==
A [[chirp]] transmitter is a [[shortwave radio]] transmitter that sweeps the [[High frequency|HF]] [[radio spectrum]] on a regular schedule. If one is monitoring a specific frequency, then a ''chirp'' is heard (in [[Continuous wave|CW]] or [[Single-sideband modulation|SSB]] mode) when the signal passes through. In addition to their use in probing [[Ionosphere|ionospheric]] properties,<ref name="jcoppens">Peter Martinez, G3PLX: Chirps and HF Propagation http://jcoppens.com/radio/prop/g3plx/index.en.php</ref> these transmitters are also used for [[over-the-horizon radar]] systems.<ref>Radar Handbook (M. Skolnik) http://www.helitavia.com/skolnik/Skolnik_chapter_24.pdf</ref>

An analysis of existing transmitters has been done using [[Software-defined radio|SDR]] technology.<ref>Pieter-Tjerk de Boer, PA3FWM: Chirp Signals analyzed using SDR http://websdr.ewi.utwente.nl:8901/chirps/</ref> For better identification of chirp transmitters the following notation is used: <repetition rate (s)>:<chirp offset (s)>, where the repetition rate is the time between two sweeps in seconds and the chirp offset is the time of the first sweep from 0&nbsp;MHz after a full hour in seconds. If the initial frequency is greater than 0&nbsp;MHz, the offset time can be linearly extrapolated to 0&nbsp;MHz.<ref name="jcoppens" />


== See also ==
== See also ==
* [[Radio propagation beacon]]
* [[Duga radar]]
* [[Ionosonde Juliusruh]]
* [[Ionosonde Juliusruh]]
* [[Radio propagation beacon]]
* [[Total electron content]]
* [[Trevor Wadley#Ionosonde]]


==References==
==References==
Line 24: Line 42:
==Further reading==
==Further reading==
{{refbegin}}
{{refbegin}}
* {{cite book |author=Davies, Kenneth |title=Ionospheric Radio |isbn= 0-86341-186-X |series=IEE Electromagnetic Waves Series #31
* {{cite book |author=Davies, Kenneth |title=Ionospheric Radio |isbn= 978-0-86341-186-1 |series=IEE Electromagnetic Waves Series #31
|date=1990 |publisher=Peter Peregrinus Ltd/The Institution of Electrical Engineers |location=London, UK|pages=93–111 }}
|date=1990 |publisher=Peter Peregrinus Ltd/The Institution of Electrical Engineers |location=London, UK|pages=93–111 }}
* {{cite journal|journal=RadCom|publisher=[[Radio Society of Great Britain|RSGB]]|title=Interpreting Digital Ionograms|author=Gwyn Williams, G4FKH|date=May 2009|volume=85|issue=05|pages=44–46}}
* {{cite journal|journal=RadCom|title=Interpreting Digital Ionograms|author=Gwyn Williams, G4FKH|date=May 2009|volume=85|issue=5|pages=44–46}}
* {{cite journal|journal=Physical Review|author1=Breit, G. |author2=Tuve, M.A.|title=A Test of the Existence of the Conducting Layer|date=1926|volume=28|issue=3|pages=554–575|doi=10.1103/PhysRev.28.554|bibcode = 1926PhRv...28..554B }}
* {{cite journal|journal=Physical Review|author1=Breit, G. |author2=Tuve, M.A.|title=A Test of the Existence of the Conducting Layer|date=1926|volume=28|issue=3|pages=554–575|doi=10.1103/PhysRev.28.554|bibcode = 1926PhRv...28..554B }}
* {{cite journal|journal=Wireless World|author=Appleton, E. V.|issue=14|date=January 1931|title=The Timing of Wireless Echoes, the use of television and picture transmission|pages=43–44}}
* {{cite journal|journal=Wireless World|author=Appleton, E. V.|issue=14|date=January 1931|title=The Timing of Wireless Echoes, the use of television and picture transmission|pages=43–44}}
* http://www.ngdc.noaa.gov/stp/IONO/ionogram.html National Geophysical Data Center
* {{cite journal|journal=RadCom|title=Interpreting Digital Ionograms|author=Gwyn Williams, G4FKH|date=May 2009|volume=85|issue=5|pages=44–46}}
{{refend}}
{{refend}}


Line 39: Line 59:
*http://ulcar.uml.edu/stationlist.html : Ionosonde (partial) station list by location
*http://ulcar.uml.edu/stationlist.html : Ionosonde (partial) station list by location
* http://car.uml.edu/common/DIDBFastStationList : DIDBase Fast Station list
* http://car.uml.edu/common/DIDBFastStationList : DIDBase Fast Station list
*http://www.iono.noa.gr : National Observatoy of Athens, Greece
*http://www.iono.noa.gr : National Observatory of Athens, Greece
*http://www.sil.sk.ca/cadi.html : Canadian Advanced Digital Ionosonde (CADI)
*http://www.sil.sk.ca/content/cadi : Canadian Advanced Digital Ionosonde (CADI)
{{refend}}
{{refend}}


[[Category:Ionosphere]]
[[Category:Ionosphere]]
[[Category:Radar]]
[[Category:Radar]]
[[Category:Infographics]]

[[Category:Radar meteorology]]

{{geophysics-stub}}

Latest revision as of 12:57, 22 October 2024

Typical ionogram indicating an F2 layer critical frequency (foF2) of approximately 5.45 MHz.
An example of an ionosonde system displaying an ionogram

An ionosonde, or chirpsounder, is a special radar for the examination of the ionosphere. The basic ionosonde technology was invented in 1925 by Gregory Breit and Merle A. Tuve[1] 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.

Components

[edit]

An ionosonde consists of:

  • A high frequency (HF) radio 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 (60 to 250 miles), 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.

An ionosonde is used for finding the optimum operation frequencies for broadcasts or two-way communications in the high frequency range.

Ionogram

[edit]

Ionogram produced by a Lowell Digisonde, with explanations for various indications and recordings.

An ionogram is a display of the data produced by an ionosonde; technically speaking one may call the data used to make the display as the ionogram but often this is simply implied. It is a graph of the virtual height of the ionosphere plotted against frequency. Ionograms are often converted into electron density profiles. Data from ionograms may be used to measure changes in the Earth's ionosphere due to space weather events.

Note that in the ionogram above the legend can be more clearly understood as having "Vx-" and "Vx+" to replace respectively "X-" and "X+". These refer to the vertical reflection of the eXtraordinary kind. "Vo-" and "Vo+" refer to the Ordinary reflection. An Ordinarily reflected wave is the one that behaves as though there were no geomagnetic field.

ARTIST is the software program used to "scale" (deduce or calculate) the characteristic parameter values shown in the table on the left. The version shown here is "5", which is the latest as of March 2022. Ion2Png is the software program used to create the ionogram image.

Chirp transmitter

[edit]

A chirp transmitter is a shortwave radio transmitter that sweeps the HF radio spectrum on a regular schedule. If one is monitoring a specific frequency, then a chirp is heard (in CW or SSB mode) when the signal passes through. In addition to their use in probing ionospheric properties,[2] these transmitters are also used for over-the-horizon radar systems.[3]

An analysis of existing transmitters has been done using SDR technology.[4] For better identification of chirp transmitters the following notation is used: <repetition rate (s)>:<chirp offset (s)>, where the repetition rate is the time between two sweeps in seconds and the chirp offset is the time of the first sweep from 0 MHz after a full hour in seconds. If the initial frequency is greater than 0 MHz, the offset time can be linearly extrapolated to 0 MHz.[2]

See also

[edit]

References

[edit]
  1. ^ F.C. Judd, G2BCX (1987). Radio Wave Propagation (HF Bands). London: Heinemann. pp. 12–20, 27–37. ISBN 978-0-434-90926-1.{{cite book}}: CS1 maint: numeric names: authors list (link)
  2. ^ a b Peter Martinez, G3PLX: Chirps and HF Propagation http://jcoppens.com/radio/prop/g3plx/index.en.php
  3. ^ Radar Handbook (M. Skolnik) http://www.helitavia.com/skolnik/Skolnik_chapter_24.pdf
  4. ^ Pieter-Tjerk de Boer, PA3FWM: Chirp Signals analyzed using SDR http://websdr.ewi.utwente.nl:8901/chirps/

Further reading

[edit]
  • Davies, Kenneth (1990). Ionospheric Radio. IEE Electromagnetic Waves Series #31. London, UK: Peter Peregrinus Ltd/The Institution of Electrical Engineers. pp. 93–111. ISBN 978-0-86341-186-1.
  • Gwyn Williams, G4FKH (May 2009). "Interpreting Digital Ionograms". RadCom. 85 (5): 44–46.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  • Breit, G.; Tuve, M.A. (1926). "A Test of the Existence of the Conducting Layer". Physical Review. 28 (3): 554–575. Bibcode:1926PhRv...28..554B. doi:10.1103/PhysRev.28.554.
  • Appleton, E. V. (January 1931). "The Timing of Wireless Echoes, the use of television and picture transmission". Wireless World (14): 43–44.
  • http://www.ngdc.noaa.gov/stp/IONO/ionogram.html National Geophysical Data Center
  • Gwyn Williams, G4FKH (May 2009). "Interpreting Digital Ionograms". RadCom. 85 (5): 44–46.{{cite journal}}: CS1 maint: numeric names: authors list (link)
[edit]
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