G.V. Kulikov – Dr.Sc.(Eng.), Professor, RTU MIREA (Moscow)
Nguyen Van Dung – Post-graduate Student, RTU MIREA (Moscow)
A.V. Nesterov – Head of Research Division, JSC «Concern «Avtomatika» (Moscow)
A.A. Lelyukh – Deputy Head of Center, JSC «MNIIRS»
Due to their energy and spectral characteristics, signals with multiple phase shift keying (M-PSK) have long been successfully used in digital information transmission systems with high channel capacity, for example, in modern satellite communication lines. Their use is laid down in various communication standards, in particular, in DVB-S and DVB-S2/S2X. Characteristics of the noise immunity of the reception of M-PSK signals against the background of white Gaussian noise are well studied. In real radio systems of information transmission at the receiver input, along with noise interference, there may be other types of interference, both unintentional and in-tentional. One of the most common is harmonic interference, for example, a disturbing narrowband signal from a neighboring radio station. The dangerous effect of such interference on the quality of information reception is confirmed by a number of studies.
The article assumes that at the receiver input there is an additive mixture of the useful signal M-PSK, white Gaussian noise and harmonic interference, characterized by intensity, detuning relative to the center frequency of the spectrum of the useful signal and random phase. Methods of statistical radio engineering analyzed the noise immunity of receiving signals with multiple phase shift keying in the presence of harmonic interference. To do this, the statistical characteristics of the distributions of processes at the outputs of the integrators of the correlation receiver were calculated, conditional for the random initial phase interference. The distribution of all these random processes, taking into account the presence of white Gaussian noise at the input of the demodulator, is assumed to be normal. Then, by averaging over the random initial phase of the interference, the dependences of the bit error probability on the signal-to-noise ratio, on the intensity of the interference and on its detuning relative to the center frequency of the useful signal spectrum are obtained.
It is shown that the reception of signals with multiple phase shift keying is very strongly influenced by harmonic interference, and with increasing positionality of the M-PSK signals, this influence is enhanced. So for M > 8, noise immunity of the reception the background of harmonic interference is noticeably reduced even with small levels of interference.
It has been established that if for noise interference the noise immunity of the bitwise reception of 2PSK and 4PSK is the same, then in the presence of harmonic interference the receiver 4PSK begins to lose significantly.
The damaging effect of interference is most pronounced when it hits the main lobe of the signal spectrum. The most dangerous is the aiming harmonic interference, the frequency of which coincides with the center frequency of the spectrum of the useful signal. To improve the noise immunity of receiving M-PSK signals against the background of harmonic interference, it is necessary to use inter-ference compensation algorithms, for example, adaptive notch filters.
- Proakis J. Digital communications: Trans. from English / Ed. by D.D. Klovsky. M.: Radio and communication. 2000. 800 p.
- Bocker P. Data transmission. V. 1. Communication techniques in data teleprocessing systems. V. I. Basics: Trans. From German / Ed. by D.D. Klovsky. M.: Communication. 1980. 264 p.
- Borisov V.I. etc. Noise immunity of radio communication systems with spreading of the signal spectrum by the method of pseudo-random adjustment of the operating frequency. M.: Radio and communication. 2000. 384 p.
- Lozhkin K.Yu., Stitsenko A.I. Noise immunity of incoherent and coherent reception of a DPSK signal under the influence of a phase-shift, harmonic or Gaussian interference // Journal of the Siberian Federal University. Ser.: Technique and technology. 2017. V. 10. № 2. P. 260−270.
- Kulikov G.V. The effect of harmonic interference on the noise immunity of the correlating demodulator of the MSK signals // Radiotehnika. 2002. № 7. P. 42−44.
- Kulikov G.V. Noise immunity of receivers of modulated signals with a continuous phase in the presence of non-fluctuations interference // Radiotehnika. 2003. № 7. P. 21−25.
- Kulikov G.V. Noise immunity of the auto-correlation demodulator of the MSK signals in the communication channel with harmonic interference // Radiotehnika. 2004. № 8. P. 20−22.
- Perov A.I. Synthesis of the optimal signal processing algorithm in a satellite navigation receiver under the influence of harmonic interference // Radiotehnika. 2005. № 7. P. 37−42.
- Kondratenko A.E., Poddubnyi V.N. Effectiveness of the impact of harmonic and Gaussian interference on a multichannel radio link with a synchronous nonlinear code channel multiplexing // Radiotehnika. 2009. № 6. P. 52−56.
- Zelenevsky V.V. Noise immunity of reception of excessive frequency-manipulated signals against the background of harmonic interference // Radiotehnika. 2002. № 7. P. 32−36.