GLONASS Changes Operating Frequencies on Four Satellites 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.