Normal-Bit-Rate Work Tape File Format

Record size: 2 x 16 bites headers followed by frames for data; variable-length format

Frame size: 96 byte (24 Long Words)

File constitution:
Each WTN file consists of double 16-byte headers except WTN-6-30, and successive 96 byte to the frames to the end of the file. Each file mostly contains all the ALSEP station data (A12, 14, 15, 16 and 17) except Apollo 11, and frames for different stations are ordered consecutively, such as A12-frame-1, A15-frame-1, A16-frame-1, A14-frame-1, A17-frame-1, A12-frame-2, A15-frame-2 etc. The station number can be discernible by the ALSEP package ID in each frame.

Header Format

Bytes	Information (16-bit integers)
1-2	3 to identify Normal-Bit-Rate Work tape
3-4	active staion code 1, 2, 3, 4, and 5 for Apollo 12, 15, 16, 14 and 17 stations, respectively, placed in consecutive 3-bit positions starting at the second most significant bit. The most significant bit is not used.
5-6	number of active stations
7-8	original 9-track tape ID number (7001 through 8109)
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

*1 Long word consists of 32 bits
*1 ALSEP word consist of 10 bits
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; 1:A12, 2:A15, 3:A16, 4:A14, 5:A17
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)
3-24	0-9	ALSEP words 1,4,7,10,13,16,19,22,25,28,31,34,37,40,43,46, 49,52,55,58,61,64
3-23	11-20	ALSEP words 2,5,8,11,14,17,20,23,26,29,32,35,38,41,44, 47,50,53,56,59,62
3-23	22-31	ALSEP words 3,6,9,12,15,18,21,24,27,30,33,36,39,42,45, 48,51,54,57,60,63
3-23	10,21	not used
24	10-31	not used

ALSEP Word Allocation

Each ALSEP word consists of 10 bits of data, and it usually includes one sample of scientific data. Please refer to Please refer to ALSEP Word Allocation to know the contents of each ALSEP word.