Gnss Time Status - Novatel WAAS G-III User Manual

Data Logs
5.2.2.3

GNSS Time Status

All reported receiver times are subject to a qualifying time status. This status gives you an indication of how
well a time is known, as shown in Table 30.
GNSS Time Status
UNKNOWN
COARSE
FINE
SATTIME
There are several distinct states that the receiver will go through:
1. UNKNOWN
2. COARSE
3. FINE
On start up, and before any satellites are being tracked, the receiver cannot know the current time. As a result,
the receiver time starts counting at GNSS week 0 and second 0.0. The time status flag is set to UNKNOWN.
After the first ephemeris is decoded, the receiver time is set to a resolution of ±10 milliseconds. This state is
qualified by the COARSE time status flag.
When the receiver knows its position and range biases are being calculated, the internal clock model will begin
modelling the position range biases and the receiver clock offset.
Modelling continues until the model is a good estimation of the actual receiver clock behavior. At this time, the
receiver time will again be adjusted, this time to an accuracy of ±1 microsecond. This state is qualified by the
FINE time status flag.
The time status flag will never improve on FINE. The time will only be adjusted again to within ±1
microsecond if the range bias gets larger than ±250 milliseconds.
WAAS G-III Reference Receiver User Manual Rev 1
Table 30: GNSS Time Status
Description
Time validity is unknown.
This time is valid to coarse precision.
Time has fine precision.
Time from satellite. This is only used in logs containing
satellite data such as ephemeris and almanac.
Chapter 5
89