V.N. Bondarenko – Dr.Sc. (Eng.), Professor,

Siberian Federal University (Krasnoyarsk)

E-mail: vnbondarenko@sfu-kras.ru

T.V. Krasnov – Ph.D. (Eng.), Associate Professor,

Siberian Federal University (Krasnoyarsk)

E-mail: krasnovtv@ya.ru

V.F. Garifullin – Ph.D. (Eng.), Associate Professor,

Siberian Federal University (Krasnoyarsk)

E-mail: vadimgar@mail.ru

D.S. Feoktistov – Senior Lecturer,

Siberian Federal University (Krasnoyarsk)

E-mail: feoktistov-d-s@mail.ru

А.А. Комаров – Design Engineer 2 cat.,

JSC «SPE «Radiosvyaz» (Krasnoyarsk)

E-mail: komarovalal@gmail.com

Correlation properties of noise-like signals commonly determine base parameters of wideband navigation system (accuracy, resolu tion capability, interference immunity). This paper shows mutual interference level increasing in code division multiple access wide band navigation system. Mutual interferences level, characterized by a maximum and effective values of 2-dimension cross correlation function of signals ensemble is determined, primarily by length of modulating pseudorandom sequence, used for noise-like 

signal generation. Code structure within length N >> 1 poorly influences on these level indicators (especially in the strip of Doppler  frequency shifts). Even less at the level of VP is affected by the noise-like signal modulation (the form of quadrature videoband com ponents). In the preferred method of broadband modulation (MSK) the shape of the main lobe of autocorrelation function is deter mined exclusively by clock frequency fT, and the sidelobe level of the module of the normalized autocorrelation function without addi tional data modulation equals 1/ N (when using M-sequences and other optimal codes). The effect of modulation of data on the cor relation properties of the MSK signals is evaluated using normalized mutual correlation function. The results of calculation of normal ized cross-correlation function of noise-like MSK signals with modulation data for codes of length N = 16383: 1) cyclic shifts of com mon maximum length sequence (consider a shift to m = 4096 elements); 2) common maximum length sequence with frequency  shifts, a multiple of the element resolution frequency (consider a shift on 40 elements resolution frequency ΔF =1/Тп); 3) different  maximum length sequences; 4) Kasami sequences. As analisys result shows, the negative impact of additional data modulation on  correlation properties of MSK-signals are expressed in the least when using the ensemble of cyclic shift of a maximum length se quence, that is common for all channels. It’s also shown, that partial frequency division of channels within acceptable limits in the  middle-wave band has lower efficiency. In this case the structure of coding sequence and the form of quadrature videoband compo nents has no influence. Two other ensembles (common maximum length sequence with frequency shifts and Kasami sequences) al most equivalent to the figure Rэ: about -42 dB. This is because the level of cross-correlation function of noise signals is determined  primarily by the correlation properties of the codes used (which is equal to the length N differ little).

1. Bondarenko V.N., Krasnov T.V., Garifullin V.F., Feoktistov D.S., Bogatyrev E.V. Pomekhoustoychivost' korrelyatsionnogo priemnika  MSK-BOC signala k sosredotochennoy pomekhe. Uspekhi sovremennoy radioelektroniki. 2017. № 12. S. 71–74. [in Russian] 2. Bondarenko V.N., Galeev R.G., Klevlin A.G. Perspektivnye sposoby modulyatsii v shirokopolosnykh radionavigatsionnykh sistemakh.  Journal of Siberian Federal University. Engineering & Technologies. 2011. T. 4. V. 1. [in Russian]
2. Aleshechkin A.M., Lopardin P.A., Valikhanov M.M., Konnov V.G. Napravleniya modernizatsii radiogeodezicheskogo kompleksa «Krabik-BM».  Uspekhi sovremennoy radioelektroniki. 2015. № 1. S. 41–43. [in Russian]
3. Krasnov T.V. Sostavnoy shumopodobnyy MSK-signal s pilotnoy i informatsionnoy komponentami. Sovremennye problemy radioelek troniki: sb. nauch. tr. [Elektronnyy resurs]. Elektron. dan. Krasnoyarsk: SFU. 2015. S. 193–196. [in Russian]