What the GLONASS ??
-GLONASS – Global Navigation Satellite System, is a space-based satellite navigation system operated by the Russian Aerospace Defence Forces. It provides an alternative to Global Positioning System (GPS) and is the only alternative navigational system in operation with global coverage and of comparable precision.
GLONASS is a global satellite navigation system, providing real time position and velocity determination for military and civilian users. The satellites are located in middle circular orbit at 19,100 km altitude with a 64.8 degree inclination and a period of 11 hours and 15 minutes. GLONASS’ orbit makes it especially suited for usage in high latitudes (north or south), where getting a GPS signal can be problematic. The constellation operates in three orbital planes, with 8 evenly spaced satellites on each. A fully operational constellation with global coverage consists of 24 satellites, while 18 satellites are necessary for covering the territory of Russia. To get a position fix, the receiver must be in the range of at least four satellites, three of which will be used to determine the user’s location and the fourth to synchronise clocks of the receiver and the three other spacecraft.
Commissioned by the network operator “NIS GLONASS” Russian companies’ time and navigation systems “and” NAVIS “experienced the availability of support GLONASS smartphone iPhone 4S from Apple.
GLONASS satellites transmit two types of signal: a standard precision (SP) signal and an obfuscated high precision (HP) signal.
The signals use similar DSSS encoding and binary phase-shift keying (BPSK) modulation as in GPS signals. All GLONASS satellites transmit the same code as their SP signal; however each transmits on a different frequency using a 15-channel frequency division multiple access (FDMA) technique spanning either side from 1602.0 MHz, known as the L1 band. The center frequency is 1602 MHz + n × 0.5625 MHz, where n is a satellite’s frequency channel number (n=−7,−6,−5,…0,…,6, previously n=0,…,13). Signals are transmitted in a 38° cone, using right-hand circular polarization, at an EIRP between 25 to 27 dBW (316 to 500 watts). Note that the 24-satellite constellation is accommodated with only 15 channels by using identical frequency channels to support antipodal (opposite side of planet in orbit) satellite pairs, as these satellites will never be in view of an earth-based user at the same time.
iPhone 4S is the first smartphone manufacturer which expressed support for GLONASS . Apple Inc. has placed information on support services GLONASS immediately after the gadget on the market. However, the implementation details were not disclosed , prompting scientists have a number of questions about the practical applicability of this function. As a result of the tests was confirmed by the ability to determine the iPhone 4S on the navigation signals from GPS and GLONASS location of the user . Processing and reception of satellite signals is implemented in iPhone 4S chipset Qualcomm, which provides even and cellular function . However, smartphone users is not possible to select a preferred navigation system – satellite navigation systems to automatically selected. The use of hybrid receivers from several navigation systems – Russian GLONASS and American’s GPS – positioning can increase the reliability and reduce the time for determining the coordinates of the user. Such benefits are of great importance in the context of poor signal reception in the high latitudes , or between urban high-rise buildings , where the Russian GLONASS satellite constellation because of the features , has an advantage over conventional GPS. In the tests, along with the iPhone 4S was Samsung Wave 3 smartphone with support for GLONASS , which uses a different chipset Qualcomm. According to the accuracy of Wave 3 and iPhone 4S showed approximately the same results . Experts pointed to the fact that the navigation device module Apple, probably provides the best quality of treatment and receive GLONASS signals . Official iPhone 4S sales in Russia will start the sixteenth of December this year.
The main contractor of the GLONASS program is Joint Stock Company Reshetnev Information Satellite Systems (formerly called NPO-PM). The company, located in Zheleznogorsk, is the designer of all GLONASS satellites, in cooperation with the Institute for Space Device Engineering (ru:Ð ÐИИ КП) and the Russian Institute of Radio Navigation and Time. Serial production of the satellites is accomplished by the company PC Polyot in Omsk.
Over the three decades of development, the satellite designs have gone through numerous improvements, and can be divided into three generations: the original GLONASS (since 1982), GLONASS-M (since 2003) and GLONASS-K (since 2011). Each GLONASS satellite has a GRAU designation 11F654, and each of them also has the military “Cosmos-NNNN” designation.
