Some Voyager LECP Documentation

Documentation

The PHA data are a list of 32 PHA data points. Each data point contains one identification byte (PHA-ID) and four PHA energy-channel values, corresponding to four of the five detectors. For particles identified as being low energy (i.e., LEPT particles) the five-dimensional PHA data point is represented by: (PHA-ID,D1,D2,D3,D4). For the high energy (HEPT) particles: (PHA-ID,D5,D2,D3,D4). The second byte of each five-byte data point is thus alternately D1 or D5 and is sometimes written D1D5 or D1/D5 to indicate this fact. It should be emphasized that while there is always a rate value assigned for a given rate-channel, the list of PHA data points depends on the identification and frequency of the incoming ions. For example, one record might have 32 PHA data points all identified with CH31, say, while another record could have 16 CH31 PHA data points, 8 CH17 PHA's and 8 CH01 PHA's.

Because the PHA output consists of five eight-bit words per event, only a very limited sampling of events is actually analyzed and transmitted... The output for each event consists of one identifier word and four 8-bit words representing the amplitudes of the signals in each of four detectors. The ID word denotes the rate channel corresponding to the analyzed event. This word is defined in Table 2-3. Depending on the rate channel into which the event falls, either the D1 or D5 signal is analyzed, as are the D2, D3 and D4 signals. The analyzed events are read out in the LECP telemetry stream during cruise and far encounter modes of operation.

Rate Channel Logic from the Gary paper

Plots of Channels With Tracks

E1/5 vs E2

E2 vs E3

E5 vs E4