High-Bit-Rate Work Tape File Format
Record size: 2 x 16 bites headers followed by frames of data; variable-length format
Frame size: 288 bytes (3 subframes of 96 bytes each)
File constitution:
Each WTH file consists of double (occasionally single-)16-byte headers, and successive 288-byte frames (3 subframes of 96 bytes each) to the end of the file. A WTH file contains only the A17 High-Bit-Rate data from the Passive Listening Mode of LSPE.
Header Format
Bytes | Information (16-bit integers) |
---|---|
1-2 | 4 to identify High-Bit-Rate Work tape |
3-4 | active staion code 5 for Apollo 17 stations. |
5-6 | number of active stations (=1) |
7-8 | original 9-track tape ID number (6001 through 6336) |
9-10 | year |
11-14 and first 4 bits of byte 15 | time of the year of the first data in msec, 36-bit integer |
Remaining bits of byte 15 and byte 16 | not used |
Data Format: In each subframe
Long Word | Bits | Data |
---|---|---|
1 | 0 | a flag bit indicating usage of computer-generated time code |
1 | 1-31 | 31msb of 35-bit time of the year in ms |
2 | 0-3 | 4lsb of 35-bit time of the year in ms |
2 | 4-7 | ALSEP tracking station ID |
2 | 8-10 | ALSEP package ID =5 |
2 | 11-15 | bit synchronizer status: bit 11=search; bit 12=verify; bit 13=confirm; bit 14=lock; bit 15=input level |
2 | 16-31 | original 7-track record number (first subframe only) |
3-22 | 0-29 | 20 LSPE data words |
3-22 | 30-31 | not used |
23-24 | 0-31 | not used |
LSPE Data Word Allocation
Each LSPE data word consists of 30 bits of data, and it is included in Long Words 3-22 in the WTH files. The data allocation of the LSPE words is described in the following link.LSPE Data Allocation