# Study and Analysis of Interference Signals of the LTE System of the GNSS Receiver
## 2 Criteria for Evaluating Solutions of Noise Elimination in a GNSS Receiver
### Diagram of the Processing of Navigation Signals in a GNSS Receiver  
The system, eliminating part of the noise of the GNSS receiver, as proposed, consists of functional modules that extend the operation model of a standard GNSS receiver. To understand how a receiver with mechanisms to eliminate some noise in a GNSS receiver works, it is first needed to understand how a receiver that does not offer such a method works. In a standard GNSS receiver, the diagram of which is shown in the figure below (Figure 1), the signals received by the antenna are subject to band-pass filtration and are amplified. \begin{table}
\begin{tabular}{c c c c c} \hline
**Block** & **Parameter** & **Unit** & **L1/E1** & **L5/E5** \\ \hline \multirow{4}{*}{Antenna system} & Directional gain & [dBi] & 3 & 3 \\  & Antenna band & [MHz] & 5 & 26 \\  & Amplification & [dB] & 47.2 & 48.8 \\  & Noise figure NF\({}_{\text{dbb}}\) & [dB] & 1.99 & 1.87 \\  & Power consumption & [mA] & 4.4 & 4.8 \\  & Phase noise at & [dBc Hz] & \(-110\) & \(-90\) \\ Frequency synthesis & \(\Delta\)F\({}_{\text{C}}\) = 1 MHz & & & \\  & Power consumption & [mA] & 2.8 & 1.8 \\  & Passband of the filter & [MHz] & 3–5.2 & 0.05–24 \\  & Amplification & [dB] & 46–81 & 42–77 \\  & Mirror frequency suppression & [dB] & \(>\)40 & 0 \\  & Power consumption & [mA] & 3.3 & 7.2 \\  & Amplification & [dB] & 93–128 & 91–126 \\  & Noise figure NF\({}_{\text{dbb}}\) & [dB] & 1.99 & 4.87 \\  & Passband & [MHz] & 3–5.2 & 0.05–24 \\  & Mirror frequency suppression & [dB] & \(>\)40 & 0 \\ Whole & A/C converter resolution & [bits] & 1.5 & 1.5 \\  & Power consumption & [mA] & 10.5 & 12.8 \\  & Integrated circuit power supply & M & \(1.2\pm 10\)\% & \\  & Operating temperature & [\({}^{\circ}\)C] & \(-40\)\(+125\) & \\ \hline \end{tabular}
\end{table} 
Table 1: Main parameters of the GNSS receiver of the Galileo constellation and GPS for the bands L1/E1 and L5/E5. Most often, this process is already taking place in the active antenna itself, which is equipped with a low-noise amplifier and filters that separate the signal transmission band of one or more GNSS systems. Next, the signal is brought down to the intermediate frequency band or baseband by mixing it with the output of the local oscillator. Then, the resulting low-pass filtered signal can be further processed in analog form or converted to digital form. Determining the position of the receiver requires knowledge of the pseudo-range from individual satellites. The values of parameters describing the movement of these satellites along their orbits, transmitted in the form of a navigation message, are also required. In order to recover the navigation data contained in the signal of a given satellite, it is necessary to focus the spectrum of the signal, which is obtained by multiplying the input signal by the local replica. The replica is the product of the course of the \(C/A\) pseudo-random sequence and the harmonic wave with a frequency as close as possible to the central frequency of the received GPS signal. In order to produce a replica properly synchronized with the signal coming from the satellite, it is necessary to determine the parameters of this signal, which is carried out at subsequent stages of processing [39]. A transmission technique called DSSS (Direct Sequence Spread Spectrum) is used in GNSS systems. The reception of this type of signals is carried out in two stages. The so-called acquisition phase followed by a tracking phase can be distinguished. The first is to determine which signals are currently reaching the receiver out of all signals transmitted in a given system. In the case of the GPS system, signals are distinguished based on the forms of their \(C/A\) distracting sequences, i.e., DS-CDMA (Direct Sequence Code Division Multiple Access) code multiple access technique. On the other hand, the GLONASS system uses FDMA (Frequency Division Multiple Access).