GLONASS Changes Operating Frequencies on Four Satellites

March 13, 2009

With no apparent advance notice or explanation, on March 11 GLONASS authorities changed the operating frequency channels of two pairs of antipodal satellites:

GLONASS 717 in orbit slot 10 was changed from channel 4 to channel -7.
GLONASS 715 in orbit slot 14 was changed from channel 4 to channel -7.
GLONASS 718 in orbit slot 17 was changed from channel -1 to channel 4.
GLONASS 725 in orbit slot 21 was changed from channel -1 to channel 4.

Modern GLONASS and GPS/GLONASS receivers should have handled the transition seamlessly. Here are the relevant Notice Advisories to GLONASS Users (NAGUs):

NAGU 032-090312
SUBJ: 10/04 (717) frequency changing 11.03.2009
1. Condition: 10/04 (717) 11.03.2009 frequency channel had been changed from 04 TO -7
2. Users are reminded to update almanacs if necessary

NAGU 033-090312
SUBJ: 14/04 (715) frequency changing 11.03.2009
1. Condition: 10/04 (715) 11.03.2009 frequency channel had been changed from 04 TO -7
2.Users are reminded to update almanacs if necessary.

NAGU 034-090312
SUBJ: 17/-1 (718) frequency changing 11.03.2009
1. Condition: 17/-1 (718) 11.03.2009 frequency channel had been changed from -1 TO 04
2. Users are reminded to update almanacs if necessary.

NAGU 035-090312
SUBJ: 21/-1 (725) FREQUENCY CHANGING 11.03.2009
1. Condition: 21/-1 (725) 11.03.2009 frequency channel had been changed from -1 TO 04
2. Users are reminded to update almanacs if necessary.

NAGU 036-090312
SUBJ: 10/-7 (717) unusable 11.03/1400-11.03/1600 MT
1.Condition: 10/-7 (717) was unusable since 11.03/1400 until 11.03/1600 MT (UTC+0300) due to maintenance
2. Users are reminded to update almanacs if necessary. 

NAGU 037-090312
SUBJ: 14/-7 (715) unusable 11.03/1400-11.03/2131 MT
1. Condition: 14/-7 (715) was unusable since 11.03/1400 until 11.03/2131 MT (UTC+0300) due to maintenance
2. Users are reminded to update almanacs if necessary. 

NAGU 038-090312
SUBJ: 17/04 (718) UNUSABLE 11.03/1400-11.03/1652 MT 
1. Condition: 17/04 (718) was unusable since 11.03/1400 until 11.03/1652 MT (UTC+0300) due to maintenance
2. Users are reminded to update almanacs if necessary. 

NAGU 039-090312
SUBJ: 21/04 (725) unusable 11.03/1400-11.03/2111 MT 
1. Condition: 21/04 (725) was unusable since 11.03/1400 until 11.03/2111 MT (UTC+0300) due to maintenance
2. Users are reminded to update almanacs if necessary. 