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Ionosonde

April 13, 2024

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.

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

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

 

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)

External links edit

April 13, 2024
ionosonde, ionosonde, chirpsounder, special, radar, examination, ionosphere, basic, ionosonde, technology, invented, 1925, gregory, breit, merle, tuve, further, developed, late, 1920s, number, prominent, physicists, including, edward, victor, appleton, term, i. 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 Typical ionogram indicating an F2 layer critical frequency foF2 of approximately 5 45 MHz An example of an ionosonde system displaying an ionogram Contents 1 Components 2 Ionogram 3 Chirp transmitter 4 See also 5 References 6 Further reading 7 External linksComponents editAn 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 nbsp 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 editA 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 lt repetition rate s gt lt chirp offset s gt 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 editDuga radar Ionosonde Juliusruh Radio propagation beacon Total electron content Trevor Wadley IonosondeReferences edit F C Judd G2BCX 1987 Radio Wave Propagation HF Bands London Heinemann pp 12 20 27 37 ISBN 978 0 434 90926 1 a href Template Cite book html title Template Cite book cite book a CS1 maint numeric names authors list link a b Peter Martinez G3PLX Chirps and HF Propagation http jcoppens com radio prop g3plx index en php Radar Handbook M Skolnik http www helitavia com skolnik Skolnik chapter 24 pdf Pieter Tjerk de Boer PA3FWM Chirp Signals analyzed using SDR http websdr ewi utwente nl 8901 chirps Further reading editDavies 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 a href Template Cite journal html title Template Cite journal cite journal a 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 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint numeric names authors list link External links edithttp 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 car uml edu common DIDBFastStationList DIDBase Fast Station list http www iono noa gr National Observatoy of Athens Greece http www sil sk ca content cadi Canadian Advanced Digital Ionosonde CADI Retrieved from https en wikipedia org w index php title Ionosonde amp oldid 1149791239 Chirp transmitter, wikipedia, wiki, book, books, library,

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