Е.V. Kuzmin - Ph.D. (Eng.), Associate Professor, School of Engineering Physics and Radioelectronics, Siberian Federal University (Krasnoyarsk) F.G. Zograf - Ph.D. (Eng.), Associate Professor, School of Engineering Physics and Radioelectronics, Siberian Federal University (Krasnoyarsk) E-mail: kuzminev@mail.ru

The most important step in the spread-spectrum signals processing is estimation of time delay, which involves «gross» interim evaluation of the incoming signal with respect to the displacement generated in the receiver reference signal. The practice of many radio electronic systems is so that it is often necessary to provide spread-spectrum signals reception at the additive mixture on a background of white Gaussian noise and various kinds of interference, in particular against the background narrow-band interference. In such circumstances the signal searching performance is significantly reduced, and at certain levels of excess noise on the signal search becomes impossible. In the present article the issue under scrutiny is a comparative analysis of the traditional and the proposed searching procedure of a spread-spectrum signal delay time on the background of white Gaussian noise and a mixture of narrow-band interference. Comparative analysis of traditional and proposed time searching procedures of spread-spectrum BPSK-signal in a white Gaussian noise and powerful narrow-band interference was conducted by statistical simulation with the number of tests being equal to 10000. Output effects of review procedures were formalized in vector-matrix form using the input training data time samples and the reference signal samples. An important feature of the proposed signal searching procedure is the usage of correlation matrix for interference processes formed in a special way on the basis of the input samples of additive mixture of signal, noise and interference. A method of correlation matrix formation allows abandoning its direct inversion, which makes the proposed searching procedure very attractive for implementation. Probability of a correct signal searching was used as a criterion for comparing the procedures. Standard accuracy BPSK-signal of global navigation satellite system GLONASS was used during the simulation. In each test the additive white Gaussian noise was generated. BPSK-signal time delay, and the frequency and phase of the narrow-band interference were designated by random variables with uniform distribution law. The article presents the dependence of the signal correct researching probability from the interference-to-signal relationship for any signal-to-noise ratios (-15, -20 and -25 dB) with different variants of input samples averaging (without averaging, as well as with three, five and ten averagings). The analysis shows that the proposed approach to the organization of the spread-spectrum signal time delay searching procedure against the narrow-band interference and noise leads to a significant gain in the quality of the selected index (in comparison with the traditional correlation processing). It was stated, that in case of signal-to-noise ratio being equal to - 15 dB, depending on the number of averages, the gain in noise immunity of the proposed procedure ranges from 6 to 23 dB. In case of signal-to-noise ratio being equal to - 20 dB the gain is 15 dB; and if the signal-to-noise ratio equals to - 25 dB, the gain is 9 dB. It was also found out, that the advantage of the proposed procedure is more vivid by using the input sample averaging.

 

1. GLONASS. Principy postroenija i funkcionirovanija / Pod red. A.I. Perova, V.N. KHarisova. Izd. 4-e, pererab. i dop. M.: Radiotekhnika. 2010.
2. SHirman JA.D., Manzhos V.N. Teorija i tekhnika obrabotki radiolokacionnojj informacii na fone pomekh. M.: Radio i svjaz. 1981.
3. Almazov V.B., Manzhos V.N. Poluchenie i obrabotka radiolokacionnojj informacii. KHarkov: VIRTA PVO. 1985.
4. Kuzmin E.V., Botov M.I., Vjakhirev V.A. Osobennosti obnaruzhenija i izmerenija parametrov radiosignalov na fone intensivnykh vneshnikh pomekh / Nauchn.-tekhn. serii. Serija «Radiosvjaz i radionavigacija». Vyp. 3. Radionavigacionnye tekhnologii / Koll. monografija // Pod red. A.I. Perova, I.B. Vlasova. M.: Radiotekhnika. 2013. S. 55-59.
5. Kuzmin E.V., Vjakhirev V.A. Sravnitelnyjj analiz pomekhoustojjchivosti posledovatelnykh procedur poiska shumopodobnogo signala // Sb. nauch. tr. «Sovremennye problemy radioehlektroniki». Krasnojarsk: Sib. feder. un-t. 2014. S. 121-124.
6. Kuzmin E.V., Vjakhirev V.A. Ocenka kachestva nerekursivnogo algoritma pomekhopodavlenija dlja dvukh sposobov formirovanija korreljacionnojj matricy additivnojj smesi // Sb. nauch. tr. «Sovremennye problemy radioehlektroniki». Krasnojarsk: Sib. feder. un-t. 2016. S. 85-88.
7. Kirillov S.N., Slesarev A.S. Bystryjj algoritm poiska i obnaruzhenija fazomanipulirovannogo signala sputnikovojj sistemy peredachi informacii, adaptivnyjj k dejjstviju uzkopolosnykh pomekh // Vestnik RGRTU. 2009. № 1 (27).
8. Interfejjsnyjj kontrolnyjj dokument GLONASS 5. 1-ja red. M. 2008.