Propagation model for signal fluctuations on transionospheric radio links

Abstract

Abstract. The complex phase method has been further extended to the problem of electromagnetic (EM) field scintillations on Earth-satellite GPS paths of propagation. The numerical and analytic technique based on the method has been developed to characterize the transionospheric channel of propagation. The effects of additional range errors due to the ionospheric electron density fluctuations in space and time have been studied taking into account the ray bending due to the inhomogeneous background ionosphere and the diffraction on local random ionospheric inhomogeneities. In the method developed, the impact of the Earth's magnetic field is accounted for by the anisotropic spatial spectrum of the ionospheric turbulence with different outer scales along and across the magnetic field lines. The variances of the EM field phase (yielding range errors) and level (log amplitude) fluctuations have been calculated for different models of the background ionospheres characterized by different height electron density profiles and total electron content. The conditions of the saturated regime of propagation, which will likely result in the degradation of a GPS navigation system, have been discussed. In addition, the scattering function of the GPS transionospheric channel of propagation has been constructed and simulated for a wideband signal.

Second-order statistics of radio wave propagation through the structured ionosphere

“…The core of the pulse propagation and scattering problems in random media is that of ÿnding the two-position and two-frequency MCF, therefore so many works have been devoted to solutions, respectively for plane wave, spherical wave, beam wave and their applications. There are several excellent books (Ishimaru, 1997;Tatarskii, 1971;Tatarskii et al, 1993;Uscinski, 1977), some earlier investigations (e.g., Fante, 1974Fante, , 1981Brown, 1972;Hong and Ishimaru, 1976;Hong et al, 1977;Ishimaru and Hong, 1975;Lee, 1974;Fremouw et al, 1980;Knepp, 1983Knepp, , 1985Liu et al, 1974;Yeh, 1977,1981;Prokhorov et al, 1975;Sreenivasiah and Ishimaru, 1979;Sreenivasiah et al, 1976;Yeh and Liu, 1982;Booker et al, 1985;Flattà e, 1983;Rino et al, 1981), and some more recent works (e.g., Kravtsov, 1992;Oz and Heyman, 1996;Wu, 1999;Liu, 1986, 1989;Young et al, 1996;Gherm et al, 2000;Samelsohn and Freilikher, 2002;Xu et al, 2003b,c,d). Besides the above literature on transionospheric propagation, Gherm et al (1997a, b) has presented a detailed numerical investigation of the two-frequency MCF for HF wave propagation in the uctuating ionosphere.…”

“…This expression provides a direct (delta function) relation for uniform plasma drift between angle-of-arrival and Doppler shift. In communications and radar systems, another view of generalized power spectrum is known as the delay-Doppler scattering function (Dana and Wittwer, 1991;Gherm et al, 2000Gherm et al, , 2001, which is obtained by integrating Eq. (30) overK ⊥ ,…”

“…Nickisch (1992) discussed the e ects of non-uniform motion among multiple screens on characteristics of scattering function (delay-Doppler power spectrum) by using phase-screen/di raction method. Gherm et al (2000) studied characteristics of propagation model for signal uctuations on transionospheric radio links by the complex phase method and earth-satellite GPS (global positioning system) paths. Gherm et al (2001) investigated wideband scattering function of the HF sky wave ionospheric uctuation channel.…”

Propagation model for transionospheric fluctuating paths of propagation: Simulator of the transionospheric channel

“…In a series of papers, this extension was used, interalia, to study the statistical properties of the HF field in the fluctuating ionosphere [e.g., Gherm andZernov, 1995, 1998;Gherm et al, 2001a]. It was also utilized to describe the transionospheric fluctuation channel of propagation [Gherm et al, 2000[Gherm et al, , 2002a[Gherm et al, , 2002b.…”

“…Among the widely known models for the transionospheric propagation are WBMOD, which is based on the phase screen approximation and works for weak scintillation [Rino, 1979] and GISM which employs a numerical solution using the multiple phase screen technique [Béniguel, 2002]. Another propagation model also valid to describe the regime of weak scintillation employs the complex phase method, or generalized Rytov's approximation [Gherm et al, 2000[Gherm et al, , 2002a[Gherm et al, , 2002b.…”