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Voyager LECP Data Analysis Handbook


Calibrations and Channel Definitions


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:


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*)
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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Updated 8/9/19, Cameron Crane


Days: Hours: Minutes: Seconds

*Since official launch
September 5, 1977, 12:56:00:00 UTC


Days: Hours: Minutes: Seconds

*Since official launch
August 20, 1977, 14:29:00:00 UTC


Manufacturer: Voyagers 1 and 2 were built in the Jet Propulsion Laboratory in Southern California.

Mission Duration: 40+ years have elapsed for both Voyager 1 and Voyager 2 (both are ongoing).

Destination: Their original destinations were Saturn and Jupiter. Their current destination is interstellar space.