*** UPDATE *** UPDATE ***
The GLONASS launched is delayed because of a problem with one of the three GLONASS-M satellites. The new launch data is October 29, 2009.
*** UPDATE *** UPDATE ***

The preparations for the next triplet GLONASS-M satellites scheduled for September 25, 2009, are progressing. Roscosmos is releasing interesting videos and pictures from the preparations. This is really exciting since this is, according to my knowledge, the first time that pictures like this are released officially by Roscosmos. A very good and positive development!

Furhtermore, last week the frequencies of two active GLONASS satellites were changed. For the two "antipodal" satellites in plane one, with GLONASS numbers 701 and 728, the frequency channel was changed from 1 to -4. This is an indication that the September launch will put 3 new satellites in plane 1. This is not surprising since it carries the two oldest satellites in the constellation, 701 from December 2003 and 712 from December 2004 with 701 being the first and therefore oldest GLONASS-M satellite. The "modernized" GLONASS satellites that live significantly longer then the first generation GLONASS satellites.

For those wondering what "antipodal" means. In GLONASS these are two satellites that fly in the same orbital plane but with an 180 degrees angle between them, meaning they are on opposite sides of the world. Several years ago the GLONASS system has been kind enough to have given back half of its frequency allocation because those frequencies were interfering with astronomical observations. However, for the GLONASS system, where the satellites are identified based on having different frequencies, this caused a small problem since there were no longer 24 different frequency channels available. However, since satellites on opposite ends of the Earth will not be observed simultaneously by an Earth bound observed the GLONASS system introduced the concept of using the same frequency channel for "antipodal" satellites.

Personally I am very much looking forward to the launch at the end this month as it will further improve the GLONASS performance and bring it very close to the GPS performance. In my "high accuracy" work (I deal with millimeters) we can now clearly see the benefit of using GPS and GLONASS compared to using just GPS.

Happy positioning and timing!

Labels: antipodal, Frequency channels, GLONASS, launch schedule