A.9   TRANSMISSION FREQUENCIES

The carrier frequency chosen to transmit the L1 navigation signal are in the ITU

assigned aeronautical satellite navigation band from 1559 MHz to 1620 MHz.  A dual

frequency system is used for the precise military signal with a second L2 transmission

in the 1250 MHz band.  Dual frequency navigation messages at L1 and L2 allow the

user to correct for ionospheric propagation effects and are incorporated into both

NAVSTAR and GLONASS. 

Unlike GPS GLONASS uses a different frequency for each satellite.  Radio frequency

carriers used by GLONASS are channelized within the bands 1240 1260 MHz and

1597 1617 MHz, the channel spacing being 7/16 or 0.4375 MHz at L2 and 9/16 or

0.5625 MHz at L1.  The carrier frequencies are multiples of channel spacing.  Currently

the number of planned channels is 24 but the Russians have given notice, Ref 4, that

this is scheduled to change in the late 1990 s to 12 with anti podal satellites

transmitting at the same frequency, see Fig A 1.

The frequency is defined from the following expressions.

L1(f) = 1602.2+0.5625KMHz

L2(f) = 1246.0+0.4375KMHz

where:

K =   0,1,2.......24  the carrier number

K = 0 is reserved for test purposes and is not used operationally.

All frequencies in each of the L1 and L2 bands are coherent and formed by the same

frequency standard.  The ratio of frequencies (K2/K1) emitted by a satellite in L1 and

L2 is 7/9.  The frequency used by particular satellites is transmitted in the almanac

transmitted by each satellite in the constellation.  Initially all GLONASS satellites used

a separate frequency.  However, since 1992 the Russians have begun to use common

frequencies for anti podal satellites.

Following the World Administrative Radio Conference in 1992 the Russians have

announced their intention to move the GLONASS frequency Band.  At WARC 92

coprimary allocations were given for Radioastronomy, 1610 to 1613 MHz and for

Mobile Satellite Systems (ground to satellite) 1610 to 1620 MHz.  From 1998 to 2005

the Russians have stated GLONASS will use the frequency band 1598.0625 MHz  (K= 

7) to 1609.3125 MHz (K=13) for L1 and the equivalent frequencies 1242.9375 MHz to

1251.6875 MHz for L2.  After 2005 GLONASS will use frequency channels K=  7 to K=

+4 with channels 5 and 6 used for technical operations (K (6) = 1605.3750 MHz L1 and

1248.6250 L2).

A 10