Fundamental Technologies

Voyager LECP Pages

Cruise 5

(From Document 618-306, Revision D)

The LECP EDR science physical record corresponds to a 9.6 minute measurement period. Any data not present within a given physical record is filled with zeroes.

A major LECP measurement cycle is 24 minutes. Hence, there are 5 physical records or 2 LECP major cycles per 48 minute period.

The physical science record structure is shown in Figure 8.3-1.

Figure 8.3-1. LECP Physical Science Tape Records

Standard Header
(60 Words)
(8 Words)
Data Block
(480 Words)
60 MF
96 Min
548 Words

All Words 32 bits.

One physical record contains a standard EDR Header followed by a science subheader followed by a science data block. One physical record contains all the data from 60 telemetry frames relevant to the experiment. Total record length is 548 words (60 MF; 9.6 min).

Figure 8.3-4 and Table 8.3-1 define the structure and contents of the LECP science record subheader.

Figure 8.3-4. LECP Science Subheader Format (CR-5)


31               15              0
31                                   0
MF 2

MF 22

MF 42
3 Spare Spare
5 Spare Spare
7 Spare Spare

Total block length is 8 EDR (32-bit) words (60 MF; 3 CMD Words).

MF shown are MF out of 60 MF.

Command Word Format:

15                                                       0

Table 8.3-1. LECP EDR Science Subheader Block Table (CR-5)

Item Word Bits


1 1 31-16 LECP Command Word    MF19
2 1 15-0 LECP Command Word    MF22
3 2 31-16 LECP Command Word    MF42
4 2 15-0 Spare
5 3 31-0 Spare
6 4 31-0 Spare
7 5 31-0 Spare
8 6 31-0 Spare
9 7 31-0 Spare
10 8 31-0 Spare

Figure 8.3-5 and Table 8.3-2 define the structure and contents of the LECP science logical records.

Figure 8.3-5. LECP EDR Science Logical Record Format (CR-5)



31 15     0 31 15      0
1 1 P1* P1 P1 P1
3 R1 R1 R1 R1
5 P2 P2 P2 P2
7 P3 P3 P3 P3
2 9 R2 R2 R2 R2
11 P4 P4 P4 P4
13 P5 P5 P5 P5
15 R3 R3 R3 R3
3 17 P6 P6 P6 P6
19 P7 P7 P7 P7
21 R4 R4 R4 R4
23 P8 P8 P8 P8

The above structure repeats 20 times for a total of 960 PHA/Rate Words.

Both P and R 40-bit blocks are treated as four 10-bit data words.

This logical record length is 24 EDR (32-bit) words (3 MF; 48 PHA/Rate words). A physical record consists of 20 logical records (60 MF; 9.6 min; 480 EDR Words).

P = PHA; R = Rate

Logical records are packed into the science data blocks of physical records according to Figure 8.3-1. The standard EDR header is defined for CR-5 in Appendix C.

A segment number (1-5) is assigned to each of the five physical records that constitute two LECP instrument cycles. Each numbered segment then always contains the same number and type of data words (both the subheader and the science data block).


The telemetry and EDR parameters for each experiment are summarized in Figure 8.10-1. The telemetry parameters include:

A. Experiment bit fields
B. Data word bit lengths
B. Data words per MF

The EDR parameters for subheader and Data Block include:

A. Minor frames
B. Time period
C. Experiment Data Words
D. EDR (32-Bit Words

Next: Cruise 6

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Last modified 4/27/05, Tizby Hunt-Ward