Modeling and studying ionograms of oblique sounding of HF radio channels for radio links of various length using a digital ionosonde with USRP platform
The paper analyses the outcomes of numerical studies into the effect of phase dispersion on broadband elements of a FMCW signal with varying central spectrum frequencies corresponding to the central frequencies of radio channels. We used the International Reference Ionosphere (IRI) model as the background ionosphere, which takes into account the spatiotemporal variability of the radio channel. The data corresponding to the extreme values in the annual distribution of solar activity were selected for modeling ionograms. The effect of the second-order phase dispersion on power delay profile distortions was analyzed.
Developing methods and software for research the effects of phase dispersion depending of the state of ionospher based on LabVIEW
Methods and software are developed for research the effects of phase dispersion, depending of the ionospher, based on LabVIEW. It is found that the leading edge increased with increasing of the third order parameter of impulse response, which leads to the case without the frequency dispersion, while trailing edge moving away from the peak, which leads to the case of linear frequency dispersion. Ionospheric radio channel with a bandwidth of 1 MHz is destroyed with the nonlinearity parameter equal to 267,4 ms/MHz2. Developed filtering methods ionograms oblique sounding ionosphere.
Changes in Quartz During Heating and the Possible Effects on Si Production
In Si and FeSi production, the main Si source is SiO2, in the form of quartz. Reactions with SiO2 generate SiO gas that further reacts with SiC to Si. During heating, quartz will transform to other SiO2 modifications with cristobalite as the stable high-temperature phase. Transformation to cristobalite is a slow process. Its rate has been investigated for several industrial quartz sources and has been shown to vary considerably among the different quartz types. Other differences in behavior during heating between these quartz sources, such as softening temperature and volume expansion, have also been studied. The quartz-cristobalite ratio will affect the rate of reactions involving SiO2. The industrial consequences and other implications of the observed difference between quartz types are discussed. Initial studies of industrial quartz were published by Ringdalen et al. In the current work, a new experimental method has been developed, and an investigation of several new quartz sources has confirmed the earlier observed large variation between different sources. The repeatability of the data has been studied and the effect of gas atmosphere investigated. The results from the earlier work are included as a basis for the discussion.