GLONASS Transmitter Specifications

This page contains information collected from the www sites listed below. I have not necessarily checked the accuracy or up-to-dateness of any data. This information will shortly be presented with experimental results.

Satellite stats: Diameter: 2.4 m, Height: 3.7 m, Solar Array: 7.2 m, Solar Array Power: 1.6 kW
GLONASS M Satellites L1 band
1602.5625 - 1615.5 MHz
L2 band
1240 - 1260 MHz
Number of Satellites 24
Approx. Distance, D, from Earth 19,100 km
Semi-Major Axis 25,440 km
Period 676 minutes [8]
Polarisation Right Hand Circular
Cesium Clocks Time Accuracy [3] 1000 ns (1µs)
EIRP 25 - 27 dBW
Antenna Gain 11 dB
Beam Width (@ 3 dB ???) ? (possibly ~ 36° [2]) 38° [4]
Bandwidth 1 MHz (C/A carrier)
10 MHz (P carrier)*
.
Band Central Frequency 1602 + n x 0.5625 MHz** 1246 + n x 0.4375 MHz** [8]
Max. Power Density [2] -42 dBW/Hz
(C/A carrier, 1601.5-1616 MHz)
-52 dBW/Hz
(P carrier, 1596.9-1620.6 MHz)
.
Signal Strength -161 dBM [8] .
* P carrier max. power is 10 dB lower than C/A carrier max. power.
** n = 1, ..., 24

For a transmitting antenna of power Pa (W), Feed losses Lf (dB), and antenna gain Ga (dBi), the maximum Effective Isotropic Radiated Power is given by:

EIRPmax = 10log(Pa) - Lf + Ga dBW [6].

Assuming that a receiver is located in the main lobe of the GLONASS beam, where the gain is Ga, the transmitter can be thought of as an isotropic antenna transmitting EIRP dBW into 4pi steradians. So the flux through a 1 m2 area on the surface of the Earth (19,100 km) over the entire transmitting bandwidth (in the main beam) will be 10EIRP/10 / (4*pi*(19.1*106)2) = 9.7*10-14 to 1.1*10-13 W.m-2 (for EIRP=25-27 dBW).

The Spectral flux (for the 1 MHz C/A carrier) will be 9.7*10-20 to 1.1*10-19 W.m-2.Hz-1 (the flux of the P carrier will be an order of magnitude less than this).

1 Jy = 10-26 W.m-2.Hz-1. So this flux is equivalent to about 107 Jy (in agreement with an NFRA prediction [7]).

If the back lobe gain of the receiver is to the order of -20 dB, then flux through the back lobe will be to the order of 100,000 Jy! This seems stronger than what is observed so there seems to be something major missing from this calculation.




  1. www.rssi.ru/SFCSIC/english.html

  2. www.ero.dk/doc98/Official/HTML/REP027.HTM

  3. samadhi.jpl.nasa.gov/msl/QuickLooks/glonassQL.html

  4. www.fas.org/spp/guide/russia/nav/glonass.htm

  5. www.oso.chalmers.se/~geo/glonass.html

  6. www.saslimited.demon.co.uk/T/faq/

  7. www.nfra.nl/craf/nwsl0001.htm

  8. giswww.pok.ibm.com/gps/