Secondary Science Byte Shift

The anomalous HRC secondary science data observed on day 2005:349 is due to a byte shift in the data in the 72-byte long secondary science buffer. The byte shift has not appeared earlier than the analog-to-digital converted portion of the secondary science data and the characteristics of the byte shift are slightly different depending on whether the HRC is configured for "Next-in-Line" telemetry format timing or "Observing" telemetry format timing.

The first table below shows an example of the byte shift when the HRC is configured with "Next-in-Line" telemetry format timing. The cells with the yellow background are the bytes that exhibit the shift. Note that the byte-shift problem is cleared at byte 64, which is the start location of the second set of scalar rate data in this mode (two housekeeping temperature items are dropped: MSIDs 2CE00ATM and 2CE01ATM). The second table shows examples of the byte-shift problem when the HRC was configured for "Observing" telemetry format timing. Once again the cells with the colored background show the bytes affected by the shift with the orange background indicating where a second byte shift occurred. Note that in "Observing" telemetry format timing the byte-shift problem is not cleared before the end of the buffer

Secondary science buffer byte number
major
frame
minor
frame
35 36 37 38 39 40 41 42 43 44 45 60 61 62 63 64 65 66 67 68 69 70 71
99055 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 d4 00 62 12 54 ff da
99056 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 df 00 6e 12 50 ff da
99057 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 f1 00 69 12 09 ff da
99058 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 cd 00 5b 11 c6 ff da
99059 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 d4 00 59 11 ba ff da
99060 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 c7 00 57 12 14 ff da
99061 0 00 bf df 20 e6 e6 7f 7f 49 50 7f 2f fd fd 7f 00 d4 00 5b 12 32 ff da
99062 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 80 4c 00 c9 00 64 11 d4 ff da
99063 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 c3 00 51 11 86 ff da
99064 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 cd 00 56 12 93 ff da
99065 0 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 00 cf 00 59 11 bd ff da

Secondary science buffer byte number
major
frame
minor
frame
35 36 37 38 39 40 41 42 43 44 45 60 61 62 63 64 65 66 67 68 69 70 71
99468 0 00 bf df 20 e6 7f 7f 49 51 7f 53 fd fd 7f 4c 4a 4a 00 dc 00 62 11 89
99468 8 00 bf df 20 e6 7f 7f 49 50 50 7f 2e fd fd 80 4c 4a 4a 00 e2 00 60 11
99468 16 00 bf df 20 e6 7f 7f 49 51 7f 53 fd fd 80 4c 4a 4a 00 cc 00 58 11 fd
99468 24 00 bf df 20 e6 e6 7f 7f 49 50 7f 2e fd fd 7f 4c 4a 4a 00 c6 00 5c 12
99468 32 00 bf df 20 e6 7f 7f 7f 49 50 7f 2e fd fd fd 7f 4c 4a 4a 00 e7 00 67
99468 40 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 cf 00 5b 11 33
99468 48 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 d2 00 5b 12 14
99468 56 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 d5 00 63 12 08
99468 64 00 bf df 20 e6 7f 7f 49 51 7f 53 fd fd 7f 4c 4a 4a 00 cb 00 65 12 89
99468 72 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 d9 00 60 11 c1
99468 80 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 ba 00 5a 12 3a
99468 88 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 e7 00 68 11 db
99468 96 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 d1 00 54 11 8d
99468 104 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 e1 00 6e 12 16
99468 112 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 b5 00 4f 11 dc
99468 120 00 bf df 20 e6 7f 7f 49 50 7f 53 fd fd 7f 4c 4a 4a 00 d4 00 62 11 ec

The facts that the byte shift does not occur until the analog-to-digital portion of the secondary science buffer and that in "Next-in-Line" telemetry format timing the problem is cleared when we get to the second scalar rate data set are likely clues to the root cause of the anomaly.


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Michael Juda

Mike Juda
Last modified: Mon Jan 23 10:38:49 EST 2006