BOC signals processing by two traditional correlator channels

Problem statement. With the development of satellite navigation systems, new navigation BOC signals are being introduced. Since the structure of BOC signals differs from traditional BPSK signals, this complicates their processing, which may require hardware changes and often leads to the need to develop new ones. Objective. Synthesis and analysis of the BOC signal processing algorithm using two BPSK correlators, comparable in accuracy to the direct method. Results. The synthesis and analysis of the BOC signal delay tracking system using two correlators, originally designed to receive only BPSK-conducting signals, are carried out. The statistical characteristics of the delay discriminator are obtained. It is shown how the accuracy and sensitivity of the obtained delay tracking algorithm are correlated with respect to the reference algorithm, which assumes the use of a signal with a digital subcarrier in the reference signal of the correlator. The pull-in characteristic are obtained. Practical relevance. The processing algorithm BOC signals that doesn't require modification of the traditional correlators of the navigation receiver is presented. This algorithm is of great practical importance, since it allows for high-precision reception of modern BOC and AltBOC signals, despite the limitations characteristic of modern navigation equipment. For example, this algorithm allows to receive Galileo E5 signals using the popular NTLab NT1065 chip. A new signal pull-in algorithm is proposed. This algorithm allows to avoid abnormal tracking errors caused by the operation of the tracking system in the side zones of the s-curve. The pull-in characteristics for various receive conditions are given.

The influence of sampling frequency and interpolation on the bit error rate of GMSK signal

The sampling rate at a given bit rate is a requirement for the speed of digital signal processors. In this regard, it is necessary to strive to reduce it in the development of electronic devices, especially portable ones. However, this can lead to an increase in the bit error rate during signal detection. Therefore, it is important to determine the degradation of signal detection with decreasing sampling frequency and to develop practical recommendations to ensure the specified quality of communication. The aim of the article is to study the influence of sampling frequency and interpolation on the bit error rate of GMSK Signal. The article considers the incoherent detection of a GMSK signal in a channel with additive white Gaussian noise, taking into account the influence of the clock synchronization error. Numerical results are presented that characterize an increase in the bit error rate with a decrease in the signal sampling frequency. It is shown that when using the cubic Farrow interpolator, there is no significant degradation in the bit error probability. The minimum number of samples per symbol is determined, at which the bit error rate is close to the theoretical values in the absence of synchronization error. The presented results can be used in development of wireless data transmission systems.

Improving the accuracy of the synthesis of the amplitude-phase distribution in an antenna array with an arbitrary geometry

Problem statement. One of the constructing antenna arrays (AA) topic is related to the determination of complex amplitudes at the input of the antenna-feeder path, which, taking into account the distortions introduced by the its, ensure the formation of an amplitude-phase distribution (APD), in which the formed DP differed minimally from the set one. The statement of the problem assumes the known number and coordinates of the location of the emitters, the DP of the radiating element in the composition of the radiating opening, a given radiation pattern. It is required to form an APD in a given opening of the AA, which ensures the formation of a DP that has a minimum deviation from the specified one. To solve the problem, the following algorithm is proposed: determination of the APD at the input of the antenna-feeder path, which ensures the formation of a given DP in the absence of distortions introduced by the antenna-feeder path; measurement for the selected directions of the generated DP with the selected APD in the presence of APD distortions introduced by the antenna-feeder path; formation of a refined APD that ensures the fulfillment of required condition in the presence of distortions introduced by the antenna-feeder path of the AA. Objective. Minimize the root-mean-square deviation of the generated PD from the one specified for the AP with the opening of an arbitrary geometry. Results. The results obtained showed: The formulation of the problem of synthesis of the APD allows us to consider, within the framework of a single approach, AA with different geometries, including AA with a non-planar radiating opening, no restrictions are imposed on the shape of the boundary, and linear (quasi-ring) AA, the emitters of which are located along an arbitrary mane. Using the proposed algorithm for the synthesis of APD, which includes three main stages: the formation of APD for a given DP; measurement of complex values of the generated DP; refinement of the APD by determining the corrections while minimizing the standard deviation (SD) between the specified and formed at the first stage of the DP, allows us to form an APD that provides a minimum SD between the specified and formed DP. The performed studies have shown that when choosing the number of angular directions in each plane, comparable to the number of emitters in this plane, there is a large difference between the given and formed DP. When the number of angular directions for measuring the DP is approximately three times greater than the number of emitters in a given plane, the SD between the specified and formed DP is close to the minimum value and practically does not change with further increase.