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Level 1B
Instrument Performance History
Mirror rotation correlated noise
Description | L1B Impact | L2 Impact | Cause | Mitigation | Schedule | History
DESCRIPTION:
A fixed pattern noise of 1 or 2 DN is present in the Terra system. This noise is correlated over a complete rotation of the scan mirror (two scan lines). A similar pattern was observed during pre-launch sensor calibration. Initial on-orbit operation and calibration includes this correlated noise. The sensor operated in this configuration until June 22, 2000, at which time there was a change in the electronic system configuration and the sensor moved into an alternate correlated noise pattern. The sensor operated with this alternate correlated noise pattern until the transition to the B-side electronics on October 31, 2000. In the B-side operating configuration, the mirror rotation correlated noise pattern matches the pattern that was present from launch until June 22, 2000. The mirror rotation correlated noise pattern has appeared in the pre-launch data set as an anomalous variation in response for each OBC sector, as well as for the first approximately 400 frames in the Earth view sector.
IMPACT TO L1B DATA SET:
At this time, the uncertainty in the L1B product introduced with the alternate noise pattern is not quantified.
ESTIMATED IMPACT TO L2 SCIENCE PRODUCTS:
{L2}
CAUSE OF EFFECT:
The noise is believed to be electronic in origin. The noise signature changes state based on the relative phase of the clock signals. The formatter reset and the change to B-side reset the Timing Generator, affecting the noise pattern.
MITIGATION APPROACH/ADDED TESTING TO CHARACTERIZE EFFECT:
None.
ESTIMATED SCHEDULE TO COMPLETE:
N/A.
HISTORY OF CHARACTERISTIC:
| Epoch Number |
Time Span | Version Number at start of epoch |
General Characteristics | Improvements | Documentation |
|---|---|---|---|---|---|
| 1 | Feb. 24, 2000 - present 2000055.1550 - present |
2.3.2.0 | DN offset depends on mirror side. Some mirror-side sector-dependent differences exist. | Not applicable. | MCST Library documents M0974, M0977. |
Description | L1B Impact | L2 Impact | Cause | Mitigation | Schedule | History
Please contact Jack Xiong with any technical questions concerning these pages.
Responsible Civil Servant:
Dr. Jack Xiong <Xiaoxiong.Xiong.1@gsfc.nasa.gov>
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Last Update: July 3, 2008