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Use of the complex dynamic cross-spectrum for indentifying sporadic radio emissions

Use of the complex dynamic cross-spectrum for indentifying sporadic radio emissions

Vladimir Kolyadin
LOFAR Transients Key Project Meeting, Meudon, December 2011

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transientskp

June 23, 2012
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  1. The using of complex dynamic cross-spectra for identification of sporadic

    radio emission Vladimir L. Koliadin The Institute of Radio Astronomy of NASU, Kharkov, Ukraine W N S NS "West" "North" "South" 0.9km 0.9km 0.9km W N S NS "West" "North" "South" 0.9km 0.9km 0.9km 00 00 11 11 000 111 000 111 00 11 00 11 W2 W1 N2 N1 S1 S2
  2. Very short baseline interferometry (VSBI) • Idea: we form local

    interferometers within the antenna system of UTR-2 • Goal: to get and use information about the phase difference between antennas • Background: the phase difference carries information about the direction of arrival
  3. UTR-2 antenna system W N S NS "West" "North" "South"

    0.9km 0.9km 0.9km
  4. Some variants of local interferometers W N S NS "West"

    "North" "South" 0.9km 0.9km 0.9km W N S NS "West" "North" "South" 0.9km 0.9km 0.9km 0 0 1 1 000 111 000 111 000 111 000 111 W2 W1 N2 N1 S1 S2
  5. DSPZ - Digital spectral analyzer (RI NASU) DSPZ u1 (t)

    u2 (t) P1 (f, t) P2 (f, t) Re ˙ R12 (f, t) Im ˙ R12 (f, t)
  6. ˙ R(f, t) = P1 (f, t) ˙ R∗ 12

    (f, t) ˙ R12 (f, t) P2 (f, t) = R11 (f, t) ˙ R∗ 12 (f, t) ˙ R12 (f, t) R22 (f, t)
  7. ˙ S1i (f, t) = FFT(u1i (t)), t ∈ Ti

    ; ˙ S2i (f, t) = FFT(u2i (t)), t ∈ Ti ; ˙ Rmn (f, t) = 1 N K i=1 ˙ Smi (f, t) ˙ S∗ ni (f, t), m, n = 1, 2
  8. Dynamic spectra: at DSPZ output • P1 (f, t) =

    R11 (f, t) - power dynamic spectrum of the 1st antenna • P2 (f, t) = R22 (f, t) - power dynamic spectrum of the 2nd antenna • A12 (f, t) = | ˙ R12 (f, t)| - cross-power dynamic spectrum • Φ12 (f, t) = arg ˙ R12 (f, t) - phase dynamic spectrum
  9. Parameters of DSPZ Frequency range: 0 . . . 33MHz

    Frequency resolution: ∆f = 4kHz Frequency channels: K = 8192 Temporal resolution: ∆t = 0.001 . . . 0.1sec
  10. False event: solar Type III burst (from sidelobes)

  11. False event: phase dynamic spectrum

  12. True event: solar Type III burst (in the main beam)

  13. True event: phase dynamic spectrum

  14. AD Leo flare star (ON + 2 OFF)

  15. AD Leo - phase dynamic spectrum, ON

  16. Test exoplanet (ON + OFF)

  17. Test exoplanet (ON + OFF)

  18. Saturn electrostatic discharges (SEDs): ON + OFF, 40s

  19. Terrestrial lightning: Phase dynamic spectrum

  20. SED: Phase dynamic spectrum

  21. Two pairs of local interferometers 00 00 11 11 00

    11 00 11 000 111 000 111 W2 W1 N2 N1 S1 S2 ments
  22. Solar sporadic radio emission (30 sec): type IIIb-III

  23. Multibase observations: Sun ments

  24. Solar event: June 7, 2011: 4 bases, power - West

    ments
  25. Solar event: June 7, 2011: 4 bases, correlation ments

  26. Two solar bursts: 4 bases, power - West ments

  27. Two solar bursts: 4 bases, correlation ments