Calculating the topocentric coordinates of the radio emission source according to the measurement results of the phase direction finder on board a mobile object

The algorithm to calculate the azimuth and the elevation angle on the source of radio emission in the topocentric system of coordinates is suggested according to the measurements done by the phase direction finder located on board a mobile object. The position of an aerial system direction finder to the earth topocentric system of coordinates can be changed. The change in the position of the aerial system influences the accuracy of calculating the bearings. The method to reduce the errors of bearing by iteration method is considered. The checking procedure of the algorithm by mathematical modelling is carried out.

On the experiment validity of the continuous medium motion detection by the waveguide method

Electronic intelligence is an important element of electronic warfare, which «is not announced and never stops». The purpose of electronic reconnaissance is to detect the emitting radio-electronic means of a potential enemy, to determine its location and radiation parameters using passive (non-emitting equipment). Electronic warfare, even in peacetime, is a promising area of development. The use of passive methods allows work to be carried out covertly, without detection. The peculiarity of the proposed method is that a priori information about the objects that reflected the signal is not required. Determination of the coordinates of the emitter is carried out by determining the delay between the arrival of the direct signal and the set of reflections from the terrain. The use of detailed, for today, satellite maps of the terrain allow with some accuracy to determine the coordinates of reflecting objects on the ground. The coordinates of the receiving point can also be determined with high accuracy using global navigation systems. The data entered the computer and the recording of signals obtained as a result of observing the air allows us to determine the coordinates of the radio emission source. The algorithm proposed in the article allows reducing the number of receiving points to one and using a phase direction finder to determine the direction of signal arrival. Evaluation of the potential accuracy of the method showed the possibility of practical application, while better results can be obtained when improving the algorithm in terms of improving the algorithms for determining the times of arrival of signals, algorithms for their extraction and post-processing of experimental data.

DIFFERENTIAL PHASE DIRECTION FINDING ERRORS FOR EMITTERS WITH PHASE-ANGLE DEPENDENCE

Выведены формульные соотношения для расчета ошибок пеленгования парного излучателя с использованием разностно-фазового пеленгатора. Оценено влияние различных параметров парного излучателя на величину ошибки пеленгования этого излучателя. Formula relations for calculating the direction finding errors of a paired transmitter using a phase difference direction finder are derived. The influence of various parameters of a paired radiator on the magnitude of the direction finding error of this radiator is estimated.

Rational approximation of P-wave kinematics — Part 1: Transversely isotropic media

In seismic data processing and several wave propagation modeling algorithms, the phase velocity, group velocity, and traveltime equations are essential. To have these equations in explicit form, or to reduce algebraic complexity, approximation methods are used. For the approximation of P-wave kinematics in acoustic transversely isotropic media, we have developed a new flexible 2D functional equation in a continued fraction form. Using different orders of the continued fraction, we obtain different approximations for (1) phase velocity as a function of phase direction, (2) group velocity as a function of group direction, and (3) traveltime as a function of offset. Then, we use them in the approximation of the group direction as a function of phase direction, and phase direction as a function of group direction. The proposed approximations have a rational form, which is considered algebraically simple and computationally efficient. The used continued fraction form rapidly converges to exact kinematics. By introducing the optimal ray into our approximations and using it for parameter definition, the convergence becomes faster, so the accuracy of the existing most accurate approximations is available by the third order, and new most accurate approximations are obtained by the fourth order of the proposed general form. The error of the most accurate version of the proposed approximations is below 0.001% for moderate anisotropic models with an anellipticity parameter up to 0.3. This high accuracy is considered to be attractive in practical implementations that use the kinematic equations and their derivatives.