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The economy of Vietnam is a socialist-oriented emerging market that heavily depends on agriculture, tourism, raw material exports, and foreign direct investment. Vietnam is industrializing and modernizing from a low starting point with weak and small economic resources. This is one of the huge obstacles to the development of Vietnam’s economy. Therefore, mobilizing and leveraging foreign direct investment are very important. In the COVID-19 pandemic, many large international corporations and enterprises are looking for investment opportunities to diversify their supply chains and limit their overdependence on the Chinese market. Vietnam has emerged as one of the brightest candidates for this capital flow due to its success in epidemic prevention. While foreign direct investment has been declining globally, foreign direct investment in Vietnam has rebounded in the second quarter of 2020 and has been on an upward trend. The real estate market remained an active segment in the third quarter of 2020. This article uses comparison, logical and statistical analysis methods to study foreign direct investment in real estate in Vietnam. The contribution analyzes the factors that influenced the desire of foreign investors to invest in the Vietnamese real estate market, based on publicly available data sources of the Foreign Investment Agency, Vietnam Ministry of Planning and Investment; and the General Statistics Office of Vietnam. Solutions at the state level to stimulate investment in Vietnam are proposed.

Introduction. Real-time calibration is essential for maintaining the performance of modern digital phased antenna array (DPAA) systems. Previous papers have proposed a method of real-time internal calibration for all receiving channels. This method uses a calibration signal (CalSig) of the same frequency spectrum as the received signal, modulated in phase and amplitude by the binary phase-shift keying (BPSK) and on–off keying (OOK) codes, respectively. With the purpose of improving the method, we propose an algorithm for estimating the phase and amplitude parameters of each receiving channel on the basis of continuous phase correlation accumulation of CalSig samples.Aim. Synthesis of algorithms and procedures for real-time internal calibration of receiving channels in digital phased antenna arrays.Materials and methods. Calibration algorithms and calibration procedure were analyzed and synthesized using the methods of systems analysis. In addition, the methods of systems engineering and technology, digital processing of radar signals and synthesis of building test models close to actual requirements were applied.Results. The advantage of the proposed calibration algorithm and calibration procedure consists in using CalSig modulated by the BPSK and OOK codes. The results obtained on a small DPAA system with four receiving channels gave the error of phase and amplitude lower than 0.3° and 0.05 dB, and the error of main beam direction lower than 0.2°. The results of testing the developed DPAA model confirmed the simplicity and high calibration accuracy of the approach under study.Conclusion. The proposed calibration algorithm and calibration procedure have the advantage over those proposed in previous research in terms of simplicity and resource efficiency. This fact determines the prospects for using the obtained results.