Fundamental Technologies

Voyager LECP Pages

Cruise 4

(From Document 618-306, Revision D)

The LECP EDR science physical record corresponds to a 192-second measurement period. Any data not present within a given physical record is filled with zeroes.

A major LECP measurement cycle is 12 minutes. Hence, there are 15 physical records or 4 LECP major cycles per 48 minutes period.

The physical science record structure is shown in Figure 7.3-1.

Figure 7.3-1. LECP Physical Science Tape Records

Standard Header
(60 Words)		 Subheader
(8 Words)		 Data Block
(320 Words)		 40 MF
192 Sec
388 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 40 telemetry frames relevant to the experiment. Total record length is 388 words (40 MF; 192 sec).

Figure 7.3-4 and Table 7.3-1 define the structure and contents of the LECP science record subheader.

Figure 7.3-4. LECP Science Subheader Format (CR-4)

EDR
Word

 Bits
31              15                0		 31                                       0
1 LECP CMD
MF 2

LECP CMD
MF 22

 Spare
3 Spare Spare
5 Spare Spare
7 Spare Spare

Total block length is 8 EDR (32-bit) words (40 MF; 2 CMD Word).

MF 1-10 = MF 1-10 when SCT60 is even (n).
MF 11-20 = MF 1-10 when SCT60 is off (n+1).
MF 21-30 = MF 1-10 when SCT60 is even (n+2).
MF 31-40 = MF 1-10 when SCT60 is off (n+3).

(n = 0, 4, 8, ..., 56)

Command Word Format:

15                                                        0
                                 

Table 7.3-1. LECP EDR Science Subheader Block Table (CR-4)

Item Word Bits

Description
1 1 31-16 LECP Command Word        MF2
2 1 15-0 LECP Command Word        MF22
3 2 31-0 Spare
4 3 31-0 Spare
5 4 31-0 Spare
6 5 31-0 Spare
7 6 31-0 Spare
8 7 31-0 Spare
9 8 31-0 Spare

Figure 7.3-5 and Table 7.3-2 define the structure and contents of the LECP science logical records.

Figure 7.3-5. LECP EDR Science Logical Record Format (CR-4)

N EDR
Word

Bits
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

P = PHA; R = Rate/Status
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 logical record consists of 3 segments which may span physical records.

PHA and Rate/Status Format:

15                             9                                                   0

Zero

  
                                 

Logical records are packed into the science data blocks of physical records according to Figure 7.3-3. The standard EDR header is defined for CR-4 in Appendix C.

Summary

The telemetry and EDR parameters for each experiment are summarized in Figure 7.10-1. The telemetry parameters include:

A. Experiment bit fields
B. Data word bit lengths
C. Data words per MF
D. Instrument cycles

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 5

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Last modified 4/27/05, Tizby Hunt-Ward
tizby@ftecs.com