LSPE Data Word Allocation
The LSPE data were acquired and downlinked at 3533 bps, high-bit-rate.
Each frame is broken into 3 subframes, each consisting of twenty 30-bit words.
Down-link information
| 3533 bits/sec, high-bit rate |
| 1060 bits/sec, normal-bit rate |
| 1.963 frames/sec, high-bit rate |
| 0.588 frames/sec, noraml-bit rate |
| 3 subframe/frame |
| 20 words/subframe |
| 30 bits/word |
Frame Constitution
Each 30-bit downlink word is subdivided into smaller data words. The first word in each
subframe is broken into one 10-bit sync word and one 5-bit seismic data sample from each of
the four seismic data (geophone data) channels. Each of the remaining 19 words of each subframe
consists of one 7-bit seismic data sample from each of the four seismic data (geophone data)
channels and a 2-bit subcom. The 2-bit subcom contains the geophone amplifier gain status,
transmitter on/off status, subframe identification, and 8-bit samples from 11 engineering
channels, four in each subframe. The geophone samples are formed from either the five
or seven most significant bits of the 8-bit A/D converter output, reading out the
most significant bit first.
LSPE Data Word 1
| Bit No | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
26 | 27 | 28 | 29 | 30 |
| Weight | 0 | 0 | 0 | 0 | 1 | 1 |
1 | 0 | 1 | 1 | 27 | 26 |
25 | 24 | 23 | 27 |
26 | 25 | 24 | 23 |
27 | 26 | 25 | 24 |
23 | 27 | 26 | 25 |
24 | 23 |
| Contents | Sync code |
Geophone No.1 |
Geophone No.2 |
Geophone No.3 |
Geophone No.4 |
LSPE Data Word 2-20
| Bit No | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
26 | 27 | 28 | 29 | 30 |
| Weight | 27 | 26 | 25 |
24 | 23 | 22 | 21 |
27 | 26 | 25 | 24 |
23 | 22 | 21 |
27 | 26 | 25 | 24 |
23 | 22 | 21 |
27 | 26 | 25 | 24 |
23 | 22 | 21 |
| Contents | Geophone No.1 |
Geophone No.2 |
Geophone No.3 |
Geophone No.4 |
Sub-com |
Sub-com contents
The contents of sub-com allocated in bits 29 and 30 of LSPE data words 2-20 are
different among the words, and some are different for sub-frame numbers. Each of the 11
8-bit engineering data is divided into 4 parts (2bits each), and put into 4 words.
| Sub-frame | Word | Content |
| 1 | 3 | RF Fire Pulses Status |
| 1 | 4,5,6,7 | LSPE MUX A/D Cal Ref Volt #1 |
| 1 | 8,9,10,11 | LSPE DC/DC Converter Volt #2 |
| 1 | 12,13,14,15 | ALSEP C/S Reserve Power |
| 1 | 16,17,18,19 | LSPE MUX A/D Cal Ref Volt #2 |
| 2 | 4,5,6,7 | ALSEP C/S PC#1 Input Voltage |
| 2 | 8,9,10,11 | ALSEP C/S Thermal Plate 6 Temp |
| 2 | 12,13,14,15 | Geophone Cal Pulse Amplitude |
| 2 | 16,17,18,19 | ALSEP C/S PCU Conv. Input Cur |
| 3 | 4,5,6,7 | ALSEP C/S Exp1&2 Power Status |
| 3 | 8,9,10,11 | LSPE Temp Monitor |
| 3 | 16,17,18,19 | ALSEP C/S Exp3&4 Power Status |
| all | 2 29bit | Geophone Cal Pulse Status |
| all | 2 30bit | Geophone Amp Gain Status |
| all | 20 | LSEP Sub-frame ID |
Geophone Status Bit Settings in Word 2
| Bit No |
| 29 | 30 |
| 0 | 1 | Calib. Pulse Off / Geophone Amp Gain Normal |
| 0 | 0 | Calib. Pulse Off / Geophone Amp Gain Low |
| 1 | 1 | Calib. Pulse On / Geophone Amp Gain Normal |
| 1 | 0 | Calib. Pulse On / Geophone Amp Gain Low |
Sub-frame ID Bit Settings in Word 20
| Bit No |
| 29 | 30 |
| 1 | 1 | Sub-frame 1 |
| 0 | 1 | Sub-frame 2 |
| 1 | 0 | Sub-frame 3 |
