A.3   SYSTEM ACCURACY

GLONASS produces both high accuracy signals specified as being for Russian military

use only and a lesser accuracy signal for civilian use.  The high accuracy channel is

provide with an anti spoofing capability Ref 1, that is controlled by the Russian Ministry

of Defence.  However, there is no equivalent of the selective availability deployed on

GPS and currently  the anti spoofing mode is not active, Ref 2.

Tests, Ref 2 of the GLONASS civil system have demonstrated accuracies of 30 m

horizontally and 20 m in altitude and 0.05 m/s in velocity.  However the specifications

provided to the ITU, Ref 3 for GLONASS state a position accuracy of 100 m and a

velocity accuracy of 0.15 m/s. Ref  1 refers to a horizontal accuracy of 100 m and a

vertical accuracy of 150 m.  A full GLONASS constellation provides a 94.7% probability

of achieving the above accuracies worldwide.  User derived time is within 1 ms of

system reference time.  Ephemeris accuracy to UTC is designed to be 5 ms.  The

Russians have classified the military accuracy of the system.

Recently a GLONASS Information Centre has been announced.  The address is:

Mr V Gorev

Scientific Information

Coordinate Centre

Military Space Forces

Kazakova ul.,23

Moscow 103064

Russian Federation

Fax: 7095 333 8133

Email: [email protected] or [email protected]#

A.4   MONITOR AND CONTROL SUBSYSTEM

As for GPS, GLONASS is controlled and monitored by a complex ground system.  Data

defining satellite position,  system time and navigation message is uploaded to the

satellites every 24 hrs with the satellite timing synchronized on every orbit, Ref 3 . 

The GLONASS monitor and control segment consists of:

  Ground control centre (GCC) Moscow

  Central synchronizer (CS) Moscow

  TT&C; stations Saint Petersburg, Yeniseisk, Komsomolsk on Amur

  navigation signal phase control system (PCS) Moscow

  quantum optical station (QOS), Komsomolsk on Amur

  navigation field control equipment (NFCE) Moscow,Komsomolsk on Amur

The monitoring and control subsystem operate autonomously and receives the data of

Earth rotation parameters, corrections to the system time relative to Russian Time &

Frequency Standard (UTC SU) externally. 

A 2