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• PHASE TRACKING LOOPS SUPPORTING IN THE SATELLITE NAVIGATION RECEIVER USING INERTIAL NAVIGATION SYSTEM MEASUREMENTS

  А.А. Cherkasova, А. Y. Shatilov, Т.А. Mukhamedzyanov

  2022-04-21

  Abstract ▼

  Satellite radio navigation systems make it possible to evaluate the user's state vector, use
  coordinates, user speed and time relative to the system scale. The requirements for the characteristics
  of these systems constantly depend on the fact that they have application features in their
  algorithms for processing radio navigation signals. One of the main characteristics of satellite
  radio navigation systems is the accuracy of estimating the user's state vector. This characteristic
  can be improved by the presence of estimates of the phase of the received radio navigation signals.
  In a satellite radio navigation system, phase estimation errors in the tracking loop have two components:
  dynamic and noise. To compensate for the noise error, it is necessary to reduce the
  equivalent noise band of the anti-aliasing filter of the phase tracking loop. However, the minimumpossible bandwidth of the smoothing filter is limited by the presence of consumer dynamics and the
  quality of the reference oscillator. As a result, in the presence of consumer dynamics, the sensitivity
  and reliability of phase tracking deteriorates. To compensate for the dynamic error in the phase
  tracking loop, information from an inertial navigation system can be used. The satellite radio navigation
  system and the inertial navigation system have complementary characteristics. The use of
  support for phase tracking loops from an inertial navigation system makes it possible to increase
  the sensitivity and reliability of its operation in the presence of consumer dynamics. It is assumed
  that with such an implementation, the sensitivity of the phase tracking loops will be limited only by
  the instability of the reference oscillator and the error of inertial measurements. To improve the
  characteristics of accuracy, sensitivity and reliability of the coherent mode of operation of the end
  device, an algorithm was developed to support phase tracking loops with measurements from an
  inertial navigation system. A study of the developed algorithm was carried out on a model that
  uses real measurements of satellite and inertial navigation systems as input data. The developed
  algorithm is implemented in the software of the NV216C-IMU inertial satellite navigation system
  prototype. Experimental studies were carried out in the conditions of automobile dynamics in open
  areas. The research results are presented in the work.

• MULTIPHYSICS SIMULATION IN ANSYS CFX AND SYSTEM COUPLING OF HEAT TRANSFER INSIDE HERMRTIC CASE OF STRAPDOWN INERTIAL NAVIGATION SYSTEM

  А.А. Medeltsev, P. А. Shapovalov, М. V. Voronov, А. I. Polukhina, P.N. Sigaleva, А.V. Frolov

  2022-04-21

  Abstract ▼

  The article presents a numerical simulation of non-stationary convective-conductive heat
  transfer of the strapdown inertial navigation system (SINS), developed in the JSC «CNIIAG».
  The numerical simulation is carried out in the ANSYS Mechanical. The aim of the study is a comprehensive
  analysis of heat exchange processes, which are characteristic to the device operation,
  including mutual spatial influence of thermal powers on each other, as well as on the block of
  sensitive elements. The simulation of heat transfer inside the hermetic case of the SINS is carried out for critical operating conditions in a strongly and weakly coupled consideration with a comparison
  of both approaches. ANSYS Mechanical, CFX and System Coupling simulation modules
  are chosen for program implementation of each approach. The k-e model of air turbulence with
  implicit consideration of the effect in the boundary layers and diffusion correction in shear flows is
  chosen for this approach. External heat exchange with ambient air is considered by setting convective
  boundary conditions on the external surfaces of the SINS, considering their orientation.
  To obtain numerical values of the heat transfer coefficients, the orientation of each surface in
  space is taken into account by using the appropriate coefficient. The presence of irregularities on
  the surfaces of the SINS in the contacts between solid components is considered by using the calculation
  of thermal resistances of the actual contact and intercontact layer. The simulation results
  of deformed state of SINS structural system, resulting from the action of a non-symmetric thermal
  field, is presented. The analysis of the obtained graphs is carried out. Stiffness indicators of the
  SINS structural system is defined as angles of deviation of sensitivity axes caused by thermal deformations.
  The obtained results make it possible to evaluate the engineering solutions for the
  quality of heat removal from the elements of the PCBs, bypassing the sensitive elements of the
  device, adopted at the stage of product layout.