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


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


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