I.V. Tyapkin1

1 Siberian Federal University (Krasnoyarsk, Russia)
1 ityapkin@sfu-kras.ru

Problem statement. Classical space-time adaptive processing (STAP) algorithms in GNSS navigation receivers with adaptive antenna arrays (AAA) effectively suppress narrowband and wideband interference. However, they introduce nonlinear distortions of the phase-frequency characteristic (PFC) of the path. This leads to group delay dispersion, correlation peak deformation, and, as a consequence, to methodological errors in pseudorange measurements, which is unacceptable for high-precision positioning.

Objective. To modify the STAP algorithm with QR decomposition for adaptive antenna arrays of navigation receivers by introducing structural constraints on the symmetry of weight coefficients, ensuring linearity of the PFC of the used FIR filters, while maintaining high adaptability, numerical stability, and interference suppression properties.

Results. A mathematical model of space-time processing with Type I FIR filters (odd length, symmetric impulse response) that guarantee linear PFC is proposed. The relationship between the minimax criterion for frequency response approximation and the MVDR minimum output power criterion is substantiated using projection methods. An orthonormal basis of the subspace of symmetric vectors is constructed, allowing a transition to a reduced space of dimension M⌈L/2⌉M⌈L/2⌉ instead of the original dimension MLML. A recurrent implementation of the algorithm based on QR decomposition with Givens rotations and a forgetting factor is developed, ensuring real-time weight updating.

Practical significance. The proposed methodology enables the implementation of interference-protected navigation receivers with AAA, in which the constant group delay of FIR filters eliminates pseudorange measurement biases caused by PFC nonlinearity. Computational efficiency (operation in the reduced space) and numerical stability (recurrent QR decomposition) make the algorithm suitable for FPGA implementation in high-precision positioning systems operating in complex interference environments.

Tyapkin I.V. Methodology for using digital FIR filters with linear phase-frequency characteristic in navigation receiver paths with adaptive antenna arrays // Achievements of modern radioelectronics. 2026. V. 80. № 7. P. 78–90. DOI: https://doi.org/10.18127/j20700784-202607-08

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