D. P. Nikitin, A. V. Veitsel

At present, an important task for the receivers of signals of global navigation satellite systems (GNSS) is to achieve a high positioning accuracy. This is due to the widening range of applications that use the navigation receivers. Standalone positioning mode provides only meter positioning accuracy, which is unacceptable for some tasks. To obtain centimeter accuracy in general apply the so-called method of differential positioning - regime RTK (real time kinematic), which uses to determine the position of ambiguous phase measurements and can obtain the accuracy of a few percentage points is equal to the wavelength of the carrier signal. However, this positioning mode requires a strong appreciation of complexity and consumer equipment that is not appropriate for some users. In this regard, for some applications, such as agriculture, where there are no guidelines on large arable lands and tractor driver must make the exact parallel to each other passages to irrigate or fertilize fields, then encouraging to use the so-called local positioning mode. This mode provides high accuracy (a few cm) in some local coordinate system whose center is the receiver position, which defined in the first moment of the navigation receiver works and requires from user only one Stand-Alone single-frequency navigation receiver. Whether a local positioning based on the determination of the increment position of navigation receiver, obtained using a delta phase measurements of the carrier frequency. In the absence of anomalous measurements, the accuracy of the phase increment depends only on increments of the various positioning errors and it does not depend from the ambiguity. This provides high accuracy local positioning, which, however, degenerate with time due to nonlinear operations in solving equations using the least squares (MLS) and the accumulation of the errors of positioning. This mode can be used for problems of agriculture, because in such applications is not critical absolute positioning accuracy, and it is important to ensure a high relative accuracy, to meet the parallel passages. To evaluate the accuracy performance of the local positioning mode and compare it to conventional stand-alone positioning presents data from experimental studies performed under conditions similar to the conditions of navigation receiver in the agriculture tasks. According to the experiments accumulated statistics of the maximal positioning errors in the plane coordinates (latitude and longitude) in the local system of coordinates. Introduced the term smoothness of the solution, which shows the positions jumps related to various factors, and characterizes the noise component of the error. Smoothness is estimated using statistical characteristics of the time derivative of the positioning errors. In addition to increasing accuracy, a local positioning provides a more smooth, without jumps associated with changes in working constellation position. With these advantages to the regime of autonomous positioning and ease of consumer equipment, as compared to the regimes of differential navigation mode using a local positioning will be important for a number of applications.