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Russia Dwells on Glonass Future

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Despite a recent round of criticism from high-ranking officials, Russia’s GLONASS system is pushing ahead with a six-satellite launch schedule in 2008 and the prospect of adding code division multiple access (CDMA) signals to future broadcasts.

GLONASS currently uses frequency division multiple access (FDMA) technology. A final decision on the long-debated CDMA question is expected imminently, according to Sergey Revnivykh, deputy head of the Russian GNSS Mission Control Center. Under the plan, CDMA signals would be introduced at L1 and L5 frequencies near GPS and Galileo signals, beginning with the GLONASS-K generation of satellites that will launch in 2010.

Addition of CDMA signals would increase potential interoperability with the other CDMA-based systems in user equipment able to process signals from satellites in multiple GNSS systems.

Revnivykh also said that Russia will conduct triple launches of modernized GLONASS satellites (GLONASS-M) in September and November this year. If successful, that would ensure completion of an 18-spacecraft constellation comprising all GLONASS-M satellites by the end of 2008.

More details on GLONASS modernization will be available at the International Satellite Navigation Conference in Moscow, April April 7-8.

Domestic Complaints
Earlier this year Russian First Deputy Prime Minister Sergey Ivanov’s created a furor with his criticism of Roscosmos, the Russian space agency, for the results to date of GLONASS.

Widely reported in Russian media and picked up and amplified in derivative reports around the world, Ivanov’s complaints focused on GLONASS’s relative inaccuracy, limited coverage, and lack of user equipment.

More recently, Russian news agency RIA Novosti reported that Russia’s Audit Chamber assessed Roscosmos operations and said GLONASS was unlikely to offer serious competition to the U.S. Global Positioning System.

In fact, GLONASS is controlled and operated by the Russian Space Forces under the direction of the Ministry of Defense (MoD), which Ivanov formerly headed, from a secured military facility in the Moscow suburb of Korolev (renamed in 1996 in honor of the chief designer of Sputnik). Some years ago, responsibility for GLONASS was nominally turned over to Roscosmos, with funding coming from both MoD and space agency budgets.

The GLONASS operations facility — the equivalent of the GPS master control station at Shriever Air Force Base, Colorado — lies a short distance away from the Roscosmos mission control center. The latter facility provides operational support for Russia’s participation in the International Space Station and other civil programs.

The primary milestone of the modernization program that GLONASS failed to meet thus far is having 18 satellites on orbit by the beginning of 2008 — the result of a short design life for the first-generation spacecraft. Sixteen satellites are currently operational.

Although Russia added six GLONASS-M satellites to the constellation during 2007 as planned, it was forced to decommission five satellites since the beginning of this year.

Performance Long Sub-Par
In any case, the fact that GLONASS’s performance is worse than GPS is not a recent development. It always has been, and in recent years Russian GNSS experts have been forthright in detailing the shortcomings. (See, for instance, the overview article on GLONASS in " GNSS Trilogy" in the January 2006 issue of Inside GNSS).

The poorer performance is the culmination of a variety of factors: poorer on-board atomic clocks, less stability and predictability in the satellite orbits (and therefore less accuracy in GLONASS broadcast ephemerides), fewer satellites providing signals, an operational control and ground monitoring segment limited to Russian territory, “biases” in the transmissions from multiple frequencies that require more complicated receiver designs to calibrate accurately, and so forth.

As for lack of coverage, that is a direct function of the number of spacecraft in orbit. Under the schedule for rebuilding and modernizing the GLONASS system, which has drawn Putin’s strong backing for more than five years, GLONASS would still not reach its full complement of satellites (24) until 2009.

Russia’s published goal for matching GPS performance is even further out — 2011. At that time officials hope to see the constellation containing all modernized satellites — including the GLONASS-M spacecraft now being launched and the GLONASS-K generation scheduled to appear next year.

Regarding the availability of user equipment or chipsets with which to make them, GLONASS does not lack for receiver manufacturers — several have operations in Russia — or silicon. Commercial GLONASS-capable receivers have been available since the early 1990s, and today at least a half-dozen well-known, but non-Russian GNSS companies offer GPS-GLONASS receivers.

What is probably bothering Russia’s leaders is the absence of affordable, domestic Russian-manufactured equipment — especially for mass-produced consumer applications and markets.

Managing the Milestones
The primary goal of the modernization program that GLONASS failed to meet thus far is having 18 satellites on orbit by the beginning of 2008. And even that should not have come as a surprise, either inside or outside Russia, because it’s a function of the operational life expectancy of GLONASS satellites.

Although Russia added six GLONASS-M satellites to the constellation during 2007 as planned, it was forced to decommission five satellites since the beginning of 2008.

Operators of the GLONASS constellation probably hoped that they could get a little more life out of a couple of the space vehicles (SVs) and meet the 18-satellite modernization milestone. But four of the recently decommissioned spacecraft, launched between 2001 and 2003, were beyond their three-year design life and had been performing poorly for some time. Only GLONASS SV number 798, launched in December 2005, could be said to have failed prematurely.

(Top: Photo of Moscow's Red Square area by Dmitri Azovtsev)

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