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PHA Priority Scheme for the Voyager LECP Experiment
In discussion of the PHA priority scheme, the shorthand notation
L -> A-B-C
should be understood to mean that if the priority of the channel associated with the PHA data telemetered in the previous interval is L, then the "priority regime" is
A-B-C.
This A-B-C priority regime notation indicates that if the priority of the PHA data in the temporary buffer of the current interval is either B or C, then a newly incident, priority A ion will supersede these data and therefore the priority A data will be stored. If a subsequent priority A ion enters, the original priority A ion will remain. Additionally if the priority of the PHA data in the buffer is C and a priority B comes in, then the priority B will stored in lieu of the priority C data. As before, a subsequent priority B will not replace the existing priority B data. All of this is another way of saying that, in the current interval,
A-B-C
means that A has highest priority, B has intermediate priority and C has lowest priority. Note, in the following, that priority 1 channels consist of heavy ions, priority 2 channels are intermediate ions, and priority 3 channels consist of protons and alpha particles.
Three discussions of this priority scheme have been found:
Peletier: Peletier, D.P., et al., IEEE Trans. Nucl. Sci., NS-24, No.1, 797, 1977
Krimigis: Krimigis, S.M., et al., Space Sci. Rev., 21, 347, 1977
Table A7: PHA Enable Conditions from an APL document
Using the shorthand notation the priority schemes given in these three documents may be compared directly:
| Document | Priority Scheme | Comments |
| Peletier | 1 → 3-2-1 2 → 1-3-2 3 → 2-1-3 | only even permutations
assumed partially detailed in text explicitly detailed in the text |
| Krimigis | 1 →
2-3-1 2 → 3-1-2 3 → 1-2-3 | explicitly detailed
in the text explicitly detailed in the text explicitly detailed in the text |
| Table A7 | 1 →
2-3-1 2 → 3-1-2 (and 3-2-1*) 3 → 1-2-3 | explicitly detailed in the
table there may be a typo in the table explicitly detailed in the table |
*If the 2,1,1,YES row of the table is replaced with 2,1,1,NO, then Table A7 will agree with the Krimigis description in complete detail. As it stands the table implies that priority 3 data will replace buffered priority 1 or 2 data, but that priority 2 data will replace priority 1 and priority 1 will replace a priority 2.
Q: Is there a typo in table A7, and is Peletier's description wrong? If none are correct, what is the actual priority scheme?
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Last modified 5/27/05, Tizby Hunt-Ward
tizby@ftecs.com