Chirp Ionosonde and Its Application in the Ionospheric Research

Vertogradov

Ponyatov

et al. 2008

Radiophys Quantum El

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We present the results of complex measurements of characteristics of HF radio signals scattered by artificial small-scale irregularities by means of oblique sounding using a chirp signal and by direction finding. On the basis of comparison of the experimental data and the calculations of aspect scattering of radio waves, the conclusion on the patch structure of an artificially disturbed ionosphere filled with small-scale field-aligned irregularities is drawn. The sizes of the patches amount to several ten kilometers, and they are separated by 100 or more kilometers. The drift speed of irregularities in the direction of the scattering vector in the plane perpendicular to the magnetic field is determined for several patches.

Section: Description Of the Experimentsmentioning

confidence: 99%

Structure and dynamics of the ionospheric region with artificial small-scale irregularities according to complex measurements of the scattered radio-signal characteristics

Vertogradov

Ponyatov

et al. 2008

Radiophys Quantum El

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“…Mathematically, when an CM ionosonde receives a signal, it performs the operation of multiplication of the received signal x r (t) and the signal x g (t) of the receiver heterodyne in the time domain [2,10]:…”

Section: Mathematical Justification and Description Of Operation Of Amentioning

confidence: 99%

“…One way of determining the spatial distribution of the electron number density is solution of the inverse problem of retrieving the N e profile from the oblique sounding data obtained in real time [1]. In recent years, oblique sounding of the ionosphere has employed widely ionosondes with chirp modulation of the signal (CM ionosondes), which have a high interference protection and a high time resolution of group delay and frequency [2][3][4][5]. However, due to new tighter requirements for the parameters of radio engineering equipment operated under the conditions of a horizontally inhomogeneous ionosphere, it is insufficient to know only the distance-frequency characteristic (DFC) determined by means of a CM ionosonde in order to retrieve the distribution of the electron number density N e on the sounding path with an acceptable accuracy.…”

Section: Introductionmentioning

confidence: 99%

Sounding of an artificially perturbed ionosphere by means of an ionosonde/position finder with chirp modulation of the signal

Vertogradov²,

Vertogradov³

et al. 2009

Radiophys Quantum El

Self Cite

We describe the operation of an ionosonde/position finder with chirp modulation of the signal. The first results of measuring the characteristics of short-wave radio signals scattered by artificial small-scale inhomogeneities, which were obtained by means of an ionosonde/position finder on the IZMIRAN-"SURA"-Rostov-on-Don path are presented. It was found that under certain ionospheric conditions, the angular and frequency selection of the scattered signals take place, in which case the signals are observed simultaneously in several frequency intervals (mainly, in three, namely, 6-9.5 MHz, 10-12 MHz, and 15-18 MHz) with different angles of incidence of radio waves in the vertical plane. In this case, the incidence angles were 20 • -35 • , 18 • -32 • , and 10 • -20 • from the horizon for the first, second, and third frequency interval, respectively. Ionograms of oblique sounding were modeled allowing for the scattering of radio waves by artificial small-scale inhomogeneities. It is shown that at frequencies from 10 to 12 MHz, aspect conditions are fulfilled for the signals ducting along the high-angle beam (Pedersen mode). At frequencies 15-18 MHz (higher than the maximum observable frequency of the forward signal on the path IZMIRANRostov-on-Don), aspect scattering conditions are fulfilled for the signals incident on a scattering area in the ascending part of the trajectory. At low frequencies 6-9.5 MHz (below the maximum observed frequency of the forward signal on the IZMIRAN-Rostov-on-Don path), the observable additional signals are caused by the scattering of radio waves by artificial inhomogeneities with subsequent relfection of the scattered signal from the Earth on the "SURA"-Rostov-on-Don path.

“…Therefore, the use of midlatitude HF radars along with high-latitude radars is of great interest for obtaining a comprehensive picture of the dynamics of ionospheric irregularities during a magnetic storm. In this case, the Russian and global networks of chirp ionosondes [18] located at mid-latitudes can be used as bistatic HF radars. The recent experiments based on the chirp-ionosonde network show that such an approach is promising for studying the dynamics of ionospheric irregularities and the wave processes in the ionosphere and magnetosphere during magnetic storms [7,10,13,19,20].…”

Section: Introductionmentioning

confidence: 99%

“…In the first campaign, the Magadan (59.7 • N and 150.5 • E) -Irkutsk (51.8 • N and 104 • E) OS path was used. In the second campaign, coordinated observations on the Russian chirp-ionosonde network[18] were performed in October 20-25.The Khabarovsk (47.5 • N and 134.5 • E) -Rostov-on-Don (47.3 • N and 39.7 • E), Magadan -Rostov-on-Don, Irkutsk -Rostov-on-Don, Khabarovsk -Irkutsk, Magadan -Irkutsk, Norilsk (69.4 • N and 88.3 • E) -Irkutsk, Norilsk -Rostov-on-Don, Khabarovsk -Nizhny Novgorod (56.1 • N and 44.1 • E), Magadan -Nizhny Novgorod, Irkutsk -Nizhny Novgorod, and Norilsk -Nizhny Novgorod paths were used in this time, whereas the Inskip (England, 53.8 • N and 2.8 • W) -Rostov-on-Don path was used in October 28-31. Twenty-four-hour…”

mentioning

confidence: 99%

Features of propagation of HF signals on mid-latitude paths under conditions of geomagnetic disturbances

Radiophys Quantum Electron

Kurkin

Vertogradov

et al. 2004

Self Cite

We present the results of experimental studies of the features of HF-signal propagation on obliquesounding paths in the Eurasian longitude sector between England and Magadan during geomagnetic disturbances. The joint analysis of the satellite data and the data of vertical and oblique sounding of the ionosphere shows that the appearance of additional signals during magnetic disturbances can be stipulated by refraction of radio waves in the region of the auroral oval and the main ionospheric trough as well as by scattering from small-scale magnetic-field-aligned irregularities near the equatorial boundary of the auroral oval. Based on calculations and comparison with experimental data of oblique sounding of the mid-latitude ionosphere, we identify the "lateral" spreading signals registered on the Magadan -Irkutsk and Inskip (England) -Rostov-on-Don paths as signals scattered by small-scale field-aligned irregularities whose location coincides with the southern boundary of the auroral oval. We show that the Russian and global chirp-ionosonde networks are promising for studying the dynamics of the main ionospheric trough and the auroral oval during geomagnetic disturbances as a manifestation of space weather in the near-Earth environment.