USER
MANUAL
MPD-1611291-A
EXACT-V2 High End Rack Modulator / Exciter
3/10/2017
MPD-1611291-A
Page 35/94
2.8.2
Warm-up Time
This part aims at describing the WARM-UP function which has been designed for
compensating the start-up delay of the OCXO (for instance, in case of AC power loss).
In order to be stable the internal temperature of the OCXO must be stabilized and equal
to 85°C. However, this could take up to 5 minutes to obtain a stable 10MHz reference.
During this unstable situation, the OCXO response is not linear and the 10MHz
regulation algorithm takes a long time to converge. The WARM-UP survey has been
defined for optimizing the 10MHz behaviour during that time.
If it is enabled, the WARM-UP function is a new state of the 10MHz regulation, during
which it is deactivated until the external reference is stable again. The 10 MHz
regulation then starts again after that state is finished.
This WARM-UP time typically takes 3-4 minutes and is limited to 10 minutes in any
case.
2.8.3
Loss of Reference Signal management (LORS)
In SFN, an accurate clock synchronization is very critical for ensuring a good SFN
operation. For this purpose, the module implements the following operating modes in
case of loss of the synchronization signal reference(s) (LORS). When losing temporal
synchronization, it can be set to automatically mute after a variable delay (Time Out
counter) also set by the user, from 0 (immediate mute) to 1440 min (24 hours), by 1
minute steps.
In the table below, it is assumed that the primary clock is 10MHz and the secondary
clock is 1 PPS:
10 MHz
1 PPS
Operating Mode
Status
Detected
Detected
Normal
No alarm
Detected
Loss of Signal
Clock_source= External
10MHz
External 1 PPS
warning
Loss of Signal
Detected
Clock_source= External 1PPS
External 10 MHz
warning
Loss of Signal
Loss of Signal
Clock_source= Internal
(Configurable Mute after LORS
TimeOut)
External 1 PPS &
10 MHz critical alarms.
Unlocked PLL
-
Configurable Mute on SFN Not
Ready
PLL_ Unlocked status
= SFN not ready
Table 4: LORS management table
Note
:
LORS is not useful when operating in MFN-Standalone configuration and shall be
considered ad reserved for Future Use (RFU).
