## 1 Introduction
### Pulsars as the Probing Signal Sources
The first example might be very strong gravitational interactions in close binary systems of neutron stars actually allows for very stringent tests of general relativity. The precise timing pulse periods for binary pulsar PSR B1913+16 confirmed the existence of the emission of gravitational waves [PERSON] et al. (2018). Again, the direct detection of gravitational waves observed as a phenomenon signed GW170817 [PERSON] et al. (2018) was related to the merger of two neutron stars. The pulsating radio signals from neutron stars can be used as probes of the different ionized media, like the interstellar medium (ISM), interplanetary region, or the Earth's ionosphere (see Figure 2). The pulsar signal propagates through the ISM (neutral atoms and ionized matter). The result of the interaction of radio waves and electrons is the possibilityof observing and testing some significant effects affecting the signal reaching the sensors. One of them is the dispersion of the radio waves, which produces frequency dependent delays. This effect is called the dispersion measure (DM) of the pulsar is proportional to the column density of free electrons integrated along the line of sight to the pulsar let us determine distances to pulsars by applying the model of electron distribution in the Galaxy (e.g., NE2001 model [23]). The next two effects observed in pulsars at long radio-waves are the interstellar scattering and scintillation [4]. These effects, clearly visible in the pulsar profiles (see Figure 3), are connected to turbulent nature of the ISM and are similar in nature to the twinkling star phenomenon (see for details [24]). Scattering observations show its dependence on the frequency, approximately as \(\sim\)\(\
u^{-4}\)[25]. In most models the turbulent nature of the Interstellar Matter is often assumed to have a Kolmogorov's spectrum of spatial electron density distribution [4]. The observations of pulsars' signals contribute to the growth of our knowledge about the galactic magnetic fields. Pulsar radio emission is usually highly polarized. The process  
Figure 3: The set of PSR J0332+5434 profiles obtained with Low Band Antennas (LBA) part of single Low Frequency Array (LOFAR) station. The effect of the influence of ionized interstellar matter on the profile with a decrease in frequency is clearly visible. Figure 2: The pulsar radio wave signal is generated in the region of neutron star magnetosphere. The signal propagates through interstellar matter, where the phenomena of dispersion and scattering occur. known as Faraday rotation (\(\theta\)) occurs when radiation passes through a Galactic magnetic field. The magnitude of the Faraday rotation depends on the wavelength of radiation:  
\[\theta=\text{ RM}\cdot\lambda^{2} \tag{2}\]  
where RM is Rotation Measure--a parameter characterizing the influence of the magnetic fields on radio waves traveling from the pulsar to the observer. The designation of Rotation Measure (RM) allows us to estimate the strength of the magnetic field [26]. For the purposes of our observations, the most important aspect of pulsars is that we receive their signals as short pulses of radiation, whenever the neutron star's radiation beam sweeps our line of sight. Since such a sweep happens exactly once per every pulsar rotation, and this rotation is extremely stable (its regularity is on par with the atomic clocks we use), this allows for relatively easy integration of a signal synchronously with the rotation of a pulsar, which in turn significantly increases the resulting signal-to-noise ratio for these inherently weak astrophysical sources. This allows for the use of pulsar radio signals as a probe of not only the interstellar medium, but also the Earth's atmosphere (and ionosphere in particular). The main objective of the work is to find an answer to a complex question. If the low frequency radio astronomical signals are so vulnerable to the ionospheric impact and GNSS techniques are one of the most commonly used tools in ionospheric studies, are there any counterparts between them?