The global navigation satellite system glonass and segments
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- User Segment
| Control Segment- The GLONASS satellite constellation is operated by the so-called ground-based Control Complex (GCC). It consists of the System Control Center (SCC) in the Moscow region and several Command Tracking Stations (CTS) located over a wide area of Russia .
The CTSs track alle GLONASS satellites in view and pass the ranging data and satellite messages to the SCC. Ranges to the satellites are measured by radar with a maximum error of between two and three meters. This information is processed by the SCC to determine clock corrections, navigation messages and status information for each satellite. The updated information is transmitted to the CTSs and uploaded to the satellites. The ranges observed by the CTSs are periodically calibrated using a laser device at the Quantum Optical Tracking Stations (QOTS). The QOTS are part of the GCC. The GLONASS system time is generated on the basis of the Central Synchronizer . Status information of the GLONASS satellite constellation is also provided by the Coordinational Scientific Information Center (CSIC) of the Russian Ministry of Defence in Moscow. The high precision of laser ranging allows use of SLR as a single source of calibration data for GLONASS ephemeris determination, providing solution of following problems: Estimation of accuracy, and calibration of radio-frequency means for GLONASS orbit measurements. Providing SLR stations with geodetic-class RF navigation receivers connected to hydrogen maser frequency standards allows monitoring of on-board clocks and use of the data for operational control of GLONASS time and ephemeris data. SLR station coordinates are used as geodetic base for the GLONASS reference frame. SLR data are used to provide declared values of ephemeris precision6. User Segment-The user segment consists of an unlimited number of GLONASS receivers. There aredifferent receiver types commercially available. A GLONASS Receiver is a device capable of determining the user position, velocity and precise time (PVT) by processing the signal broadcasted by satellites. Any navigation solution provided by a GNSS Receiver is based on the computation of its distance to a set of satellites, by means of extracting the propagation time of the incoming signals traveling through space at the speed of light, according to the satellite and receiver local clocks. Notice that satellites are always in motion, so previous to obtaining the navigation message, the satellite’s signal is detected and tracked. The receiver’s functional blocks that perform these tasks are the antenna, the front-end and the baseband signal processing (in charge of acquiring and tracking the signal). Once the signal is acquired and tracked, the receiver application decodes the navigation message and estimates the user position. The Navigation Message includes: Ephemeris parameters, needed to compute the satellite’s coordinates Time parameters and Clock Corrections, to compute satellite clock offsets and time conversions Service Parameters with satellite health information. Almanacs, needed for the acquisition of the signal by the receiver. It allows computing the position of all satellites but with a lower accuracy than the ephemeris. The ephemeris and clocks parameters are usually updated every half-an-hour, whereas the almanac is updated at least every six days. For more information, please refer to GLONASS Interface Control Document which specifies parameters of interface between GLONASS space segment and user equipment in L1 and L2 Bands. They are similar as those of GPS satellites. One may classify GLONASS receivers according to the signal components processed in the same way as it is done in the case of GPS receivers. We make the distinction of: • L1 Single Frequency Receivers, • L1 and L2 Dual-Frequency Receivers, • C/A-Code Receivers, • P-Code Receivers. In contrast to GPS antennas the GLONASS antennas require an increased band width in order to measure different frequencies. In the case of a combined GLONASS/GPS receiver the antenna even has to be designed for GLONASS and GPS frequencies7. Results
GLONASS's operations are generally divided into three distinct segments: 1. Space Segment: Consists of a satellite network and includes GLONASS satellites in Earth orbit. 2. Control Segment: The satellite system consists of ground stations that perform observation and monitoring processes. 3. User Segment: Includes end-user devices and receivers using GLONASS. Users can access location information by receiving satellite signals through this segment. Together, these three segments of GLONASS are coordinated to ensure proper system operation. They are end-user devices that receive GLONASS signals and use location data. Thus, overall, we conclude that these segments together enable GLONASS to provide accurate positioning services worldwide and segments are used to make GLONASS work more comprehensively. Discussion About users' use of navigation systems Dworkin, V.V. and Karutin, S.N., "Building a system for accurate determination of the position of users of global navigation satellite systems", On the basics and parts of the space segment Fatkulin, R., Kossenko, V., Storojev, S., Zvonar, V., Chebotarev, V. ., "GLONASS Space Segment: Satellite Constellations", GLONASS-M and GLONASS-K Spacecraft and the main features. In general, Glonass navigation system is discussed in detail in the book "GLONASS" by S. Karutin, N. Testoedov, A. Tyulin, A. Bolkunov. Conclusion As a result, GNSS technology has revolutionized many aspects of our lives with the development of the modern era and has a wide range of applications that can improve efficiency and safety in various industries. Reference https://glonass-iac.ru/en/about_glonass/ https://gge.ext.unb.ca/Resources/gpsworld.june10.pdf https://skybrary.aero/articles/global-orbiting-navigation-system-glonass https://glonass-iac.ru/en/about_glonass/ https://gssc.esa.int/navipedia/index.php?title=GLONASS_Space_Segment https://gssc.esa.int/navipedia/index.php?title=GLONASS_Ground_Segment https://gssc.esa.int/navipedia/index.php?title=GLONASS_User_Segment Yüklə 33,91 Kb. Dostları ilə paylaş:
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