High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes
The ionospheric D-layer is a narrow bandwidth radar target often with a very small scattering cross section. The target autocorrelation function can be obtained by transmitting a series of relatively short coded pulses and computing the correlation between data obtained from different pulses...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2002-09-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/20/1469/2002/angeo-20-1469-2002.pdf |
| _version_ | 1811259277546881024 |
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| author | T. Turunen T. Turunen T. Turunen A. Westman I. Häggström G. Wannberg |
| author_facet | T. Turunen T. Turunen T. Turunen A. Westman I. Häggström G. Wannberg |
| author_sort | T. Turunen |
| collection | DOAJ |
| description | The ionospheric D-layer
is a narrow bandwidth radar target often with a very small scattering cross
section. The target autocorrelation function can be obtained by transmitting a
series of relatively short coded pulses and computing the correlation between
data obtained from different pulses. The spatial resolution should be as high
as possible and the spatial side lobes of the codes used should be as small as
possible. However, due to the short pulse repetition period (in the order of
milliseconds) at any instant, the radar receives detectable scattered signals
not only from the pulse illuminating the D-region but also from 3–5
ambiguous-range pulses, which makes it difficult to produce a reliable estimate
near zero lag of the autocorrelation function. A new experimental solution to
this measurement problem, using a selected set of 40-bit random codes with 4
µs elements giving 600 m spatial resolution is presented. The zero lag is
approximated by dividing the pulse into two 20-bit codes and computing the
correlation between those two pulses. The lowest altitudes of the E-layer are
measured by dividing the pulse into 5 pieces of 8 bits, which allows for
computation of 4 lags. In addition, coherent integration of data from four
pulses is used for obtaining separately the autocorrelation function estimate
for the lowest altitudes and in cases when the target contains structures with
a long coherence time. Design details and responses of the experiment are
given, and analysed test data are shown.<br><br><b>Key words. </b>Radio science (signal
processing); Ionosphere (plasma temperature and density; instruments and
techniques) |
| first_indexed | 2024-04-12T18:28:19Z |
| format | Article |
| id | doaj.art-89f4add88da44098948ebeaa6abafc8a |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-04-12T18:28:19Z |
| publishDate | 2002-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-89f4add88da44098948ebeaa6abafc8a2022-12-22T03:21:10ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762002-09-01201469147710.5194/angeo-20-1469-2002High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codesT. Turunen0T. Turunen1T. Turunen2A. Westman3I. Häggström4G. Wannberg5Correspondence to: T. TurunenEISCAT Scientific Association, P.O.Box 164, SE-981 23 Kiruna, Sweden(tauno.turunen@eiscat.com)EISCAT Scientific Association, P.O.Box 164, SE-981 23 Kiruna, SwedenEISCAT Scientific Association, P.O.Box 164, SE-981 23 Kiruna, SwedenEISCAT Scientific Association, P.O.Box 164, SE-981 23 Kiruna, SwedenThe ionospheric D-layer is a narrow bandwidth radar target often with a very small scattering cross section. The target autocorrelation function can be obtained by transmitting a series of relatively short coded pulses and computing the correlation between data obtained from different pulses. The spatial resolution should be as high as possible and the spatial side lobes of the codes used should be as small as possible. However, due to the short pulse repetition period (in the order of milliseconds) at any instant, the radar receives detectable scattered signals not only from the pulse illuminating the D-region but also from 3–5 ambiguous-range pulses, which makes it difficult to produce a reliable estimate near zero lag of the autocorrelation function. A new experimental solution to this measurement problem, using a selected set of 40-bit random codes with 4 µs elements giving 600 m spatial resolution is presented. The zero lag is approximated by dividing the pulse into two 20-bit codes and computing the correlation between those two pulses. The lowest altitudes of the E-layer are measured by dividing the pulse into 5 pieces of 8 bits, which allows for computation of 4 lags. In addition, coherent integration of data from four pulses is used for obtaining separately the autocorrelation function estimate for the lowest altitudes and in cases when the target contains structures with a long coherence time. Design details and responses of the experiment are given, and analysed test data are shown.<br><br><b>Key words. </b>Radio science (signal processing); Ionosphere (plasma temperature and density; instruments and techniques)https://www.ann-geophys.net/20/1469/2002/angeo-20-1469-2002.pdf |
| spellingShingle | T. Turunen T. Turunen T. Turunen A. Westman I. Häggström G. Wannberg High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes Annales Geophysicae |
| title | High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes |
| title_full | High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes |
| title_fullStr | High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes |
| title_full_unstemmed | High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes |
| title_short | High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes |
| title_sort | high resolution general purpose d layer experiment for eiscat incoherent scatter radars using selected set of random codes |
| url | https://www.ann-geophys.net/20/1469/2002/angeo-20-1469-2002.pdf |
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