| Description: | When initially purchased, it was not realized that the SEANAV Fiber Optic Gyros (FOG) have
a predictable life time before degradation and failure. In October 2012, the FOG
end-of-life issues started to appear. The problem was not diagnosed immediately.
When the internal FOG lasers go below a selected intensity the SEANAV enters a "NO GO"
mode and data ceases. When this failure cause was finally identified we learned it was
possible to delay the failure by adjusting internal laser thresholds somewhat, not affecting
data quality.
The specified data outages are due to these NO GO periods and data resumed when laser
thresholds were further lowered. Ultimate failure was however reached on Nov 1, 2012 at
16:24 UTC.
GPS data from the SEANAV was still available and data records with date, time, latitude,
longitude, northvelocity (m/s), eastvelocity (m/s) were collected into a new data stream
named magnavgpsM1.a1. These data do not contain any ship attitude data such as
roll/pitch/yaw.
Note that ship attitude data is also collected from motion sensors associated with other
MAGIC instruments. These alternate/surrogate motion data sources might be useful
depending on the particular need. Contact the SEANAV mentor for discussion. |