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| Titel |
Fast comparison of IS radar code sequences for lag profile inversion |
| VerfasserIn |
M. S. Lehtinen, I. I. Virtanen, J. Vierinen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 8 ; Nr. 26, no. 8 (2008-08-05), S.2291-2301 |
| Datensatznummer |
250016188
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2291-2008.pdf |
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| Zusammenfassung |
A fast method for theoretically comparing the posteriori variances produced
by different phase code sequences in incoherent scatter radar (ISR)
experiments is introduced. Alternating codes of types 1 and 2 are known to be
optimal for selected range resolutions, but the code sets are inconveniently
long for many purposes like ground clutter estimation and in cases where
coherent echoes from lower ionospheric layers are to be analyzed in addition
to standard F-layer spectra.
The method is used in practice for searching binary code quads that have
estimation accuracy almost equal to that of much longer alternating code
sets. Though the code sequences can consist of as few as four different
transmission envelopes, the lag profile estimation variances are near to the
theoretical minimum. Thus the short code sequence is equally good as a full
cycle of alternating codes with the same pulse length and bit length. The
short code groups cannot be directly decoded, but the decoding is done in
connection with more computationally expensive lag profile inversion in data
analysis.
The actual code searches as well as the analysis and real data results from
the found short code searches are explained in other papers sent to the same
issue of this journal. We also discuss interesting subtle differences found
between the different alternating codes by this method. We assume that
thermal noise dominates the incoherent scatter signal. |
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