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


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,


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 (the relevant portion of these documents are enclosed):

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:


Peletier 1 -> 3-2-1 only even permutations assumed

2 -> 1-3-2 partially detailed in text

3 -> 2-1-3 explicitly detailed in the text

Krimigis 1 -> 2-3-1 explicitly detailed in the text

2 -> 3-1-2 explicitly detailed in the text

3 -> 1-2-3 explicitly detailed in the text

Table A7 1 -> 2-3-1 explicitly detailed in the table

2 -> 3-1-2 (and 3-2-1 *) there may be a typo in the table

3 -> 1-2-3 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?