Time tagging problem
====================
We have found a problem in time tagging of several MEA products.
=== MEA Moments
Depending on the mode (Low, Med, High), velocity moments should have a different periodicity :
* Low mode : 16s
* Med mode : 4s
* High mode : 2s
However, we found that regularly, there is a shift in the TI0 value.
Rather than a regular periodicity of 4s in Med mode:
----
Record TI0
1 t1
2 t2 = t1 + 4s
3 t3 = t2 + 4s
4 t4 = t3 + 4s
5 t5 = t4 + 4s
----
We found some inconsistencies :
----
Record TI0
1 t1
2 t2 = t1 + 4s
3 t3 = t2 + 8s // Shift of 4 seconds
4 t4 = t3 + 0s // Return to normal timetag
5 t5 = t4 + 4s
----
In the case of Low mode, rather than a regular increase of 16s, we can found :
----
Record TI0
1 t1
2 t2 = t1 + 16s
3 t3 = t2 + 20s // Shift of 4 seconds
4 t4 = t3 + 12s // Return to normal timetag
5 t5 = t4 + 16s
----
So, it seems that there is regurlarly a shift of 4s in TI0, as if onboard software has a synchronisation bug,
and take an incorrect value of TI0.
=== Examples
* link:/documents/PB_DATATION/2017-02-03/MEA1_L1_VML__20170203_V00.txt[]
* link:/documents/PB_DATATION/2017-02-03/MEA1_L1_VMM__20170203_V00.txt[]
* link:/documents/PB_DATATION/2017-02-03/MEA2_L1_VML__20170203_V00.txt[]
* link:/documents/PB_DATATION/2017-02-03/MEA2_L1_VMM__20170203_V00.txt[]
NOTE: same king of problem occurs for other products PAP's, OMN, 3D
