А.I. Loskutov – Dr.Sc. (Eng.), Head of Department «Telemetry Systems and Integrated Information Processing», Military Space Academy named after A.F. Mozhaysky (St. Petersburg). E-mail: email@example.com
А.B. Artjushkin – Ph.D. (Eng.), Associate Professor, Military Space Academy named after A.F. Mozhaysky (St. Petersburg). E-mail: firstname.lastname@example.org
А.А. Bjankin – Ph.D. (Eng.), Professor, Military Space Academy named after A.F. Mozhaysky (St. Petersburg). E-mail: email@example.com
А.S. Dunikov – Head of Laboratory, Military Space Academy named after A.F. Mozhaysky (St. Petersburg). E-mail: firstname.lastname@example.org
N.А. Pivovarov – Ph.D. (Eng.), Deputy Head of the Test center and the Use of Space Assets, First State Test Cosmodrome (c. Mirnyj). E-mail: email@example.com
At the present stage of development of rocket and space technology requirements imposed on the reliability and validity of the regis-tration of telemetry data ground receiving station is much tougher. Analysis of the processes of transmission of telemetry data via radio showed that a significant impact on the quality of reception of telemetry results have complicated conditions receive the signal, characterized by random fluctuations of the amplitude of a radio telemetry group due to the vibrations of rocket and space technology, the body rotation and separation stages of the product. Therefore one of the main directions of development of ground-based telemetry systems is the development of new transmission and reception of telemetry data approaches that ensure the required accuracy of the functioning of the on-board equipment data. One of the important elements that affect the quality of reception of the information system is a symbol timing. Thus existing methods do not take into account symbol timing signal reception changing conditions, in particular fluctuations of the signal amplitude.
One approach to solve this problem is to build an adaptive system symbol timing, taking into account, when it detects the boundaries of the elements of the bit sequence, changing the amplitude of the received signal. To this end, the article formalized mathematical model of the symbol timing based on multiway search-threshold detection. At the same time, as an a priori law of probability distribution of the amplitude fluctuations of the received telemetry signal group, is considered a generalized Rayleigh law which is most characteristic of the stage of removal of products of rocket and space technology.
To form a threshold bit sequence elements edge detection algorithm is developed, the use of which allows the system to adapt to the symbol timing change the depth and speed of fading group received telemetry signal amplitude. The algorithm is used two strategies of forming the detection threshold based on a statistical evaluation of the maximum and minimum values of the correlation integral and the three-point parabolic interpolation. Choice of strategy is dependent on the signal amplitude of velocity fluctuations. Setting the threshold value is performed depending on a given probability of false alarm.
The results of the developed algorithm simulation showed that, to ensure a high probability of correct detection at the level of 0,9 is necessary to set the value of the probability of a «false alarm» in the ground receiving and recording equipment within 10-1-10-3.
Thus, the proposed algorithm is adaptive formation detection threshold boundaries symbols when taking group telemetry signal with fluctuating amplitude, in contrast to the existing algorithms, allows, when entering the symbol timing of ground receiving and recording station, take account of changing conditions of reception of information, in particular changes in the depth and amplitude fluctuation rate telemetry signal group. Adapting to changing reception conditions ensures reliable detection of the boundaries of the elements of the bit sequence in the face of considerable depth fading and low signal/noise ratio.
Bjankin A.A., Dunikov A.S. Sovremennoe sostojanie i problemnye voprosy primenenija
sistem sinkhronizacii informacionno-telemetricheskikh sredstv pri ispytanijakh
obektov raketno-kosmicheskojj tekhniki i puti ikh reshenija / Sb. trudov
Vserossijjskojj nauchno-prakticheskojj konferencii «Sovremennye problemy uluchshenija
taktiko-tekhnicheskikh kharakteristik raketno-kosmicheskojj tekhniki, ee sozdanija,
ispytanija i ehkspluatacii». T. 1. SPb.: VKA im. A.F. Mozhajjskogo. 2013. S. 48–52.
Teorija optimalnykh metodov priema pri fluktuacionnykh pomekhakh. M.: Gosudarstvennoe
ehnergeticheskoe izdatelstvo. 1961.