S.O. Mel’nikov1, S.B. Makarov2, D.A. Tkachenko3

1-3 Peter the Great St. Petersburg Polytechnic University (St. Petersburg, Russia)

1 7atom7@mail.ru; 2 makarov_sb@spbstu.ru; 3 dtkach@spbstu.ru

Problem statement. To increase the reliability of receiving frequency-modulated signals with a compact spectrum and extended phase trajectories in a channel limited by a given frequency mask and in the presence of additive white Gaussian noise (AWGN), algor ithms for receiving a sequence of signals are used. However, these al gorithms require significant computing resources. Computational costs can be reduced by using quasi-coherent algorithms with decision feedback. The aim o

Problem statement. To increase the reliability of receiving frequency-modulated signals with a compact spectrum and extended phase trajectories in a channel limited by a given frequency mask and in the presence of additive white Gaussian noise (AWGN), algorithms for receiving a sequence of signals are used. However, these algorithms require significant computing resources. Computational costs can be reduced by using quasi-coherent algorithms with decision feedback.

The aim of the work is to increase the noise immunity of receiving frequency—modulated signals with intersymbol phase interference by using quasi-coherent algorithms with double decision feedback at the level of individual symbols. These algorithms provide minimal computational complexity in practical implementation.

Results. New algorithms for receiving frequency-modulated signals with extended phase trajectories are presented, which provide a given width of the occupied frequency band and an increased rate of decrease in the level of out-of-band emissions. It is shown that the use of a double decision feedback algorithm provides an energy gain in comparison with a quasi-coherent element-by-element reception without feedback, amounting to about 1.1 dB with an error probability BER = 1·10-4 in the AWGN channel for power-law sinusoidal frequency pulses.

When using the algorithm with double decision feedback, when receiving a message of the order of 1 Mbit, the processing time is 2.72 seconds, which is 12 times less than the Viterbi algorithm. The indicated reduction in processing time allows to increase the amount of information transmitted within a given time interval.

Practical significance. The proposed quasi-coherent reception algorithms with limited computational complexity can be used in communication systems where strict requirements are placed on computational complexity, spectral compactness and energy efficiency. Such systems include the space segment of broadband access, short-range mobile communication lines, as well as satellite data transmission and digital broadcasting systems. The implementation of algorithms on software-defined radio platforms (SDR) ensures their practical applicability and flexibility of tuning to channel and signal parameters.

f the work is to increase the noise immunity of receiv ing frequency—modulated signals with intersymbol phase interference by using quasi-coherent algorithms with double decision feedbac k at the level of individual symbols. These algorithms provide minimal computational complexity in practical implementation. Results. New algorithms for receiving frequency-modulated signa ls with extended phase trajector ies are presented, which provid e a given width of the occupied frequency band and an increased rat e of decrease in the level of out-of-band emissions. It is show n that the use of a double decision feedback algorithm provides an ene rgy gain in comparison with a quasi-coherent element-by-element reception without feedback, amounting to about 1.1 dB with an e rror probability BER = 1·10 −4 in the AWGN channel for power-law sinusoidal frequency pulses. When using the algorithm with double decision feedback, when re ceiving a message of the order of 1 Mbit, the processing time i s 2.72 seconds, which is 12 times less than the Viterbi algorithm. The indicated reduction in processing time allows to increase the amount of information transmitted within a given time interval. Practical significance. The proposed quasi-coherent reception a lgorithms with limited computational complexity can be used in communication systems where strict requirements are placed on comp utational complexity, spectral compactness and energy efficienc y. S u c h s y s t e m s i n c l u d e t h e s p a c e s e g m e n t o f b r o a d b a n d a c c e s s, s h ort-range mobile communication lin es, as well as satellite data transmission and digital broadcasting systems. The implementati on of algorithms on software-defined radio platforms (SDR) ensu res their practical applicability and flexibility of tuning to channel and signal parameters.

Mel’nikov S.O., Makarov S.B., Tkachenko D.A. Q u a s i - coherentdecisionfeedbackalgorithmforreceivingspect rally efficient frequency-modulated signals with intersymbol phase interference. Rad iotekhnika. 2026. V. 90. № 3. P. 76−89. DOI: https://doi.org/10.18127/j00338486-202603-07 (In Russian)

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