The goal of online monitoring (OM) is the quickest user warning concerning the initiation of operating failure
SNS.
The tasks of online monitoring include:
•The estimation of pseudorange measurement errors based on GLONASS and GPS navigation space vehicle (NSV) in real time.
• User informing concerning the values of these errors.
The errors of signals measurements of spase navigation system (SNS) included the following items:
• errors owing to ionospheric effect;
• errors owing to tropospheric effect
• ephemeris errors of
NSV;
• the errors of clockandfrequency corrections (CFC) of
NSV.
Online monitoring task:
the estimation of joint errors effect, added with ground and space segments of GLONASS and GPS systems, i.e. including the effect of ephemeris errors and clockandfrequency corrections.
Online functions:
• The estimation of pseudorange measurement errors based on GLONASS and GPS NSVin real time.
• User informing concerning the values of these errors.
The estimation of pseudorange measurement errors are generated in discrete kind (index "In"), meaning the limited value of measurement error. Table 1 describes the correspondence of index to the value of limited error of pseudorange measurement ( e ) (metrical scale).
Table 1. The correspondence of index to value of limited error estimation of pseudorange measurement (e).
ln 
0 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
e[Í] 
2.4 
3.4 
4.85 
6.85 
9.65 
12 
15 
20 
30 
50 
100 
200 
500 
1000 
3000 
>3000 
The values e,
corresponding to index in the range from 0 to 4 inclusive, coincide with the values of URA, transfered in navigation message GPS. So the user after taking the integrity message and GPS navigation message, could equally treat the estimations of pseudorange measurement errors.
The valuese,corresponding the index in the range from 5 to 15 inclusive, are chosen from considerations of convinience for the following analysis.
