Russia launches Glonass satellite, a boost for India

Discussion in 'Strategic Forces' started by LETHALFORCE, Feb 27, 2011.

  1. LETHALFORCE

    LETHALFORCE Moderator Moderator

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    http://www.thehindu.com/news/international/article1492915.ece

    Russia has successfully launched a next-generation navigation satellite for its Glonass global communication system.

    The Glonass-K satellite was hauled into orbit on Saturday morning from the northern Plesetsk space centre by the upgraded Soyuz 2-1b launcher, featuring advanced digital avionics and a more powerful Fregat upper stage. The new satellite has a longer design life, more navigation channels and is smaller than previous Glonass-M spacecraft.

    Saturday's launch will increase the deployed Glonass grouping to 23 satellites, one short of the minimum needed to provide 100-per cent global coverage.

    In December the launch of three Glonass-M satellites failed when the carrier rocket crashed into the ocean after it was filled with excessive fuel and deviated from course.

    Russia plans to launch five Glonass satellites this year to replace the ones that crashed and deploy back-up satellites.

    Glonass will be integrated with the U.S. Global Positioning System (GPS), as well as with the European Union's Galileo system and China's Compass network when they are deployed. Experts said the use of a two-signal receiver that supports both GPS and Glonass increases reliability by 15 per cent.

    Under a 2007 accord, Russia agreed to share the Glonass signal with India. India will be the only country to have access to the military segment of the Glonass system, which will enable the Indian military to greatly improve the accuracy of its land-, sea-, air and space-launched weapon systems. In September the two countries signed a deal to jointly manufacture Glonass/GPS twin system receivers and other navigational equipment.
     
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  3. warriorextreme

    warriorextreme Senior Member Senior Member

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    I wish our GAGAN also takes off soon..
    we should not depend on other countries on such things
     
  4. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    GLONASS is meant for global connectivity.

    GAGAN is meant for civilians in India.

    IRNSS is our military equivalent.

    But both GAGAN and IRNSS are regional services. This means GLONASS is very much required.
     
  5. Atul

    Atul Founding Member

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    This means the missiles will hit right on target.
     
  6. Yusuf

    Yusuf GUARDIAN Administrator

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    If one has a gps system, how do you shift over to glonass? Frequency or some thing else? Can you have a dual use system which works at a flick of a button?
    If Brahmos for instance is using gps for navigation, is there an in built system to shift to glonass or will it require a re-fit of its navigation system?
     
  7. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    You HAVE to buy new receivers or get license from Russia to manufacture them at home.
    Brahmos, MKI etc will need new GLONASS receivers. They are currently using French made GPS receivers.

    Brahmos already has a GLONASS receiver.
    http://indrus.in/articles/2010/08/26/brahmos_missile_04631.html

    Once GLONASS is ready, we will gradually start dumping GPS within our military, including the Navy. When we get superior singnals from GLONASS, why will we want to use the civilian GPS signals again. GLONASS military signals provide 4 to 6 cm accuracy while the civilian GPS signals that we are allowed to use are accurate upto 30cm. The military GPS signals are accurate upto 2cm. So, there is no question of using GPS ever again.

    Only us Civvie car wallas and town planning wallas will continue using the cheaper and better GPS. The civilian GLONASS signals aren't particularly good compared to GPS.
     
  8. Yusuf

    Yusuf GUARDIAN Administrator

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    I don't assume its going to be an expensive re-fit. Gps receivers, the civilian ones are cheap, by military budget at least.
     
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  9. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    Yeah. It's not a big thing.
     
  10. Agnostic_Indian

    Agnostic_Indian Regular Member

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    good news...this may help anti pirate operations and border security in kashmir.
     
  11. Dark Sorrow

    Dark Sorrow Respected Member Senior Member

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    Nowadays frequency band of overall of all system overlap, so receivers won't be a problem. The main issue here is the back circuit also called a.k.a. the driver circuit which handles the CDMA(Code Division Multiple Access). If you get this driver circuit the interoperability is not an issue. This is where licensing takes place.
     
  12. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    The signals are coded. Everybody uses Digital signals. One receiver will not work on another if the PN sequences generated are unique to that receiver. So, we have no choice but to upgrade everything to GLONASS.
     
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  13. Yusuf

    Yusuf GUARDIAN Administrator

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    I read that new phone models being shipped to Russia contain GPS and GLONASS compatible receivers. They are doing this to prevent the 25% additional duty on non glonass compatible phones. So how is that being done?
     
  14. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    One receiver with 2 different PN Generators. Civilian tech is allowed to evolve for obvious reasons and is much simpler. Military tech is not and the receiver design is much more complex and perhaps with ECCM capabilities. We will have to build different receivers for both because Russia will not be too keen on building a GPS/GLONASS receiver module with American involvement.

    Who would want a civilian GPS clubbed with a military GLONASS? No point if we are not allowed military grade GPS signals.
     
  15. Dark Sorrow

    Dark Sorrow Respected Member Senior Member

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    Bro, that is what I said, the back up circuit is responsible for pseudo random noise(number)/pseudo noise/pseudo number/chipping sequence generation, spreading of the information signal on a wider band and reconstruct/de-spreading the incoming signal.
    Hence if your circuit driver can handle this then you can identify both signals.
     
  16. Dark Sorrow

    Dark Sorrow Respected Member Senior Member

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    PN generation is done by MPUs or special DSP units. One unit suffices for all operation.
    I beg to differ w.r.t. this statement. The circuit drivers in military equipment are made to handle bit length(aka word size) of chipping sequence of very length(of length few millions bits) while civilian equipment has to handle length of chipping sequence max. up to 10,000 bits. A small difference also exist in the receiver.
     
  17. Rage

    Rage DFI TEAM Stars and Ambassadors

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    Hey prada, blackwater,


    I was conducting some research on the GLONASS the other day and came across a thesis by John Swann of the Institute of Engineering Surveying and Space Geodesy of the University of Nottingham, U.K. He conducted controlled trials on both GLONASS and GPS sat-nav systems to examine the possibilities and challenges of integrating both, and found crucial biases in the pseudorange measurements of the GLONASS satellites. This, he said, was due to the fact that GLONASS satellites broadcast on different, and differentially delayed, frequencies, via the R/F sections of receivers. But, separately, no such biases in pseudorange measurements were found in the carrier-phase operations of the GLONASS. Now, from what little I know about trilateration, wouldn't this hamper differential positioning? And how would you go about solving this problem? If the R/F sections on different receivers were identical, the error source would cancel out wouldn't it? But that was not found to be the case with the test receivers.


    Here is the paper, replete with least-squares adjustments and traverse computations, that may appeal to the more technically-minded:

    http://etheses.nottingham.ac.uk/1284/1/311911.pdf
     
    Last edited: Mar 1, 2011
  18. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    I don't understand this. How can GLONASS "broadcast" via the R/F sections of the receivers?

    I have not yet read the thesis, so I will do that once the download finishes.
     
  19. Rage

    Rage DFI TEAM Stars and Ambassadors

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    No, I meant to say that the article alleges the differential delays in frequencies of signals are due to the differential R/F sections on receivers.
     
  20. p2prada

    p2prada Stars and Ambassadors Stars and Ambassadors

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    I read some of the thesis. I understood your question and here is my answer.

    GPS works on 2 frequencies, the same as GLONASS. However there is a difference. GPS generates 2 separate PN codes for transmission and that the GPS signals sent from each individual satellite has it's own modulation code.

    The GLONASS too sends 2 PN codes as 2 separate frequencies. But the reciever has a need to identify the satellite. In GLONASS all satellites work on the same modulation code which is completely opposite to GPS. This means if the GLONASS satellites use only one set of frequencies like GPS does then there is no way the receiver can identify each individual satellite because the codes are all the same. So, what GLONASS does is it sends PN codes at different frequencies for different satellites. Depending on the frequency the satellite is identified.

    Differential delay of signals that is handled by the GLONASS receiver is for this reason alone.

    The R/F section of the transmitter and receiver on GLONASS is based on FDMA or Frequency Division Multiple Access where multiple frequencies are sent to different users at the same time. This removes the problem of any errors occuring at the receiver because all the satellites are identified using the different frequencies generated. The design allows 25 users access to GLONASS signals at a particular time. But due to interference with other space agencies channels from 15-20 are not used on some satellites.

    The R/F section of Tx and Rx on GPS is based on CDMA or Code Division Multiple Access where a multiple codes are accessed in the same channel bandwidth.

    In the thesis Swann says the the L1 and L2 bands used in GLONASS are divided by a factor of 0.5625 and 0.4375 resply for every channel. This means each of the satellites work at a frequency that is properly spaced(differentially) for identification.

    In conclusion, the GLONASS is a better system because of the technology used.

    However his thesis is more in relation to augmentation of GPS in tandem with GLONASS for civilian use rather than military use which does not work out for us because the Russians will not give up GLONASS military signals to US and US will not do the same with GPS. Thus a receiver system that works together for military use will not exist.
     
    Last edited: Mar 2, 2011

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