R&S M3SR 4100 Series, Руководство по эксплуатации, Страница: 343 / 706

Operating Manual 6175.4760.02 – 01 4.7
M3SR Series 4100 Basics of ALE-2G LP
Protection level 2 requires a time quality of at least 4 and protection level 1 a time quality of
at least 6. The time server always has a time quality of 1 (= 20 ms). Time quality 0 is reserved
for stations with absolute time.
For maintaining synchronism, a time acquisition protocol is started as soon as a certain time
uncertainty threshold has been exceeded. In the course of this the exact time is acquired
from the time server or any other station within the network. The acquired time quality is al-
ways poorer by one level than the actual time quality of the inquired station. Therefore sta-
tions which are no time server cannot obtain time qualities better than 2. This protocol also
is protected for as long as the time uncertainties are tolerated by the link protection proce-
dure.
For stations which do not have at all any information on the date or time or whose time un-
certainty is too great, another time acquisition protocol is implemented. Due to the lack of
time information, however, this protocol cannot be protected. It has been provided mainly for
stations entering the network at a later stage.
4.3.2.1 Achieving Network Synchronism
In order to achieve network synchronism when installing the system, proceed as follows:
Installing the time server:
1. Enter the linking protection key.
2. Enter the ALE net time with a precision of ±10 s or better.
3. Set the configuration parameters for example as follows:
- Link protection level: 1 or 2
- Fine time request: ON
- Coarse time request: ON
- Unprotected time request: ON
- Passive time acquisition: ON
- Time request interval: 5 min
- Time server: ON
After setting the time server parameter to ON, the radio starts broadcasting the net time.
As per definition the time server has the exact time, the time server radio should not
be switched off. In the off-state the internal clock of the radio has a precision of only
±7.5 ppm.