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Interferometric Direction Finding on an FM/CW Ionosonde
Author(s) -
Sherrill W. M.,
Green T. C.,
Martin P. E.
Publication year - 1972
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs007i002p00251
Subject(s) - azimuth , ionosonde , elevation (ballistics) , remote sensing , interferometry , ionogram , geodesy , ionosphere , optics , geology , phase (matter) , physics , electron density , quantum mechanics , astronomy , geophysics , electron
DF interferometry on an FM/CW sounder has been successfully performed using a three‐element crossed baseline array and twin channel receiver modified for linear FM synthesis. Measured baseline phase differences obtained from a sum‐and‐difference CRT phase display were used to compute incident azimuth and elevation. Phase ambiguities were resolved by prior knowledge of the sounder location. Measurements in San Antonio, Texas, on cooperative FM/CW targets in Pueblo and Boulder, Colorado, showed essentially constant azimuth within ±2°, commensurate with ionospheric lateral deviation effects. Corresponding elevation data showed increasing elevation angle with frequency indicative of increasing ray penetration. The azimuth/elevation measurements were made without benefit of IF spectral analysis for time‐delay‐mode resolution. Consequently, measurements were successful over those frequency ranges at which the sounder signal dominated interfering stations. This limitation would be eliminated by the use of cross‐spectrum analysis at the receiver output.