The improvement of noise immunity of a communication system is an effective way to increase the capacity of communication systems, which would provide more qualitative service for a larger number of users. This task can be solved by lowering the noise threshold of a phase-locked loop (PLL) in these systems if the dynamic properties of the device are preserved. The literature review indicates that such a device with improved noise immunity has already been implemented, but the effects of noise and modulation on its dynamic behavior were analyzed separately. This article is devoted to the analysis of the behavior of a digital firmware PLL under the simultaneous influence of noise and modulation of the input signal. The article depicts the structure of the classical digital PLL and its modifications and explains key differences between them.
The simulation of the classical PLL with either absence or presence of noise at the device input was carried out. The simulation results show that the PLL is not able to detect all phase changes when the noise is present. Besides, the modified PLL has a wider working frequency range than the classical one under noisy conditions. The investigations of the PLL dynamic behavior with the simultaneous influence of random noise and Binary Phase Shift Keying (BPSK) modulated input signal was performed. The results of the research show that the duration of the transient processes during the processing of the BPSK modulated signal in the modified device is at least twice as low as that for the classical one. In addition, the number of errors during the signal detection increases faster for the classical PLL than for the modified one when the noise level rises. The use of the modified PLL in modern communication systems gives an opportunity to increase their capacity.
- B. B. Purkayastha and K. K. Sarma, A digital phase locked loop based signal and symbol recovery system for wireless channel. New Delhi, India: Springer, 2015.
- G. Kolumban, PLL Applications. Hong Kong, China: Wiley Encyclopedia of Electrical and Electronics Engineering, 2005.
- D. Abramovitch, “Phase-Locked Loops: A Control Centric Tutorial”, in Proc.American Control Conference 2002”, vol. 1, pp. 1-15, 2002. DOI: https://doi.org/10.1109/ACC.2002.1024769
- K. Vesolovskii, Systems of mobile radio communication. Moscow, Russia: Goriachaia liniia-Telekom, 2006. (Russian)
- V.N. Akimov, et al. Systems of phase synchronization. Moscow, USSR: Radio i svjaz, 1982. (Russian)
- J. G. Proakis and M. Salehi, Communication Systems Engineering. New Jersey, USA: McGraw-Hill Companies Inc., 2003.
- A. Bondariev, “Noise locking ranges and covering ranges of synthesizers”, Bulletin of Vinnytsia Politechnical Institute, vol. 62, no. 5, pp. 113-116, Vinnytsia, Ukraine: Vinnytsia Politechnical Institute, 2005. (Ukrainian)
- A. Bondariev, “Nonlinear parametrical synthesis of a monitoring phasal detector”, Radioelectronics and informatics, vol. 32, no. 1, pp. 27-30, Kharkiv, Ukraine: NURE, 2006. (Ukrainian)
- A. Bondariev, “Reduction of noise threshold of phasal auto-adjustment of frequency”, Series of Radio Electronics and Telecommunication, vol. 557, pp. 25-29, Lviv, Ukraine: Lviv Polytechnic National University, 2006. (Ukrainian)
- Yu. Bobalo, A. Bondariev, and I. Maksymiv, “Determination of acceptable parameters area in modified detector of quadrature phase shift keying signals”, Series of Radio Electronics and Telecommunication, vol. 818, pp. 5-10, Lviv, Ukraine: Lviv Polytechnic National University, 2015.
- A. Bondariev, I. Maksymiv, and T. Maksymyuk, “Method for increasing the energy efficiency of HQPSK signals”, Series of Radio Electronics and Telecommunication. vol. 849, pp.18-22, Lviv, Ukraine: Lviv Polytechnic National University, 2016.
- A. Bondariev, S. Altunin, I. Horbatyi, and I. Maksymiv, “Firmware implementation and experimental research of the phase-locked loop with improved noise immunity”, Eastern-European Journal of Enterprise Technologies, series Information and Controlling System, vol. 5, no. 5 (95), pp. 17-25, 2018.
- A. Bondariev and S. Altunin, “Measurement of The Phase-Transfer Function of The Software Phase-Locked Loop”, in Proc. International Conference on Information and Telecommunication Technologies and Radio Electronics (UkrMiCo-2017), Odesa, Ukraine: O.S. Popov Odesa National Academy of Telecommunications, 2017.
- R. E. Best, Phase-locked loops: design, simulation, and applications (professional engineering). New York, USA: McGraw-Hill Companies Inc., 2003.
- A. Bondariev, and S. Altunin, “Investigation of the conditions of synchronization loss in the software phase-locked loop”, Bulletin of Vinnytsia Politechnical Institute, vol. 131, no. 2, pp. 91-96, Vinnytsia, Ukraine: Vinnytsia Politechnical Institute, 2017.
- A. Bondariev, “Noise and dynamic features of a modified device for phasal auto-adjustment of frequency”, Radiotekhnika, vol. 146, pp. 171-177, Kharkiv, Ukraine: NURE, 2006. (Ukrainian)
- Xilinx 7 Series FPGAs Data Sheet: Overview”. https://www.xilinx.com/support/documentation/data_sheets/ds180_7Series_Overview.pdf, April 25, 2019.