The Galileo Energetic Particles Detector
Galileo EPD Handbook
Appendices
Appendix A. EDR File Structure
Table of Contents
- 1. EPD Housekeeping Decom (below; please scroll down)
- 2. Spacecraft Clock (below; please scroll down)
- 3. EPD Subsystem Telemetry
- 4. EPD Telemetry Packet Definitions
1. EPD Housekeeping Decom
Source: GLL-SRD 90-07-10, Rev. C, pp. 4.7-17 - 4.7-18 (June 1984)
| RIM | MOD 91 | LRS Bits | No. of Bits | Channel No. | Function |
| Any | 41 | 2129-2136 | 8 | S-1687 | EP MISC S1 |
| " | 47 | 2129-2136 | 8 | S-1688 | EP MISC S2 |
| " | 59 | 2129-2136 | 8 | S-1689 | EP MISC S3 |
| " | 03 | 2129-2133 | 5 | S-1690 | EPD SCAN 1 |
| " | 03 | 2134-2136 | 3 | S-1691 | EP MTR POS - 0,1,2,3,4,5,6,7 |
| " | 00 | 2161-2168 | 8 | S-1692 | EP CMDS EX |
| " | 00 | 2177-2184 | 8 | S-1693 | EP CM CODE |
| " | 00 | 2186 | 1 | S-1694 | EP PWR MON - NORMAL, INTER |
| " | 02 | 2129-2136 | 8 | S-1695 | EP MOTOR T |
| " | 04 | 2129-2136 | 8 | S-1696 | EPD SCAN 2 |
| " | 10 | 2129-2136 | 8 | S-1697 | EP LEMMS T |
| " | 16 | 2129-2136 | 8 | S-1698 | EP CMS T |
| " | 22 | 2129-2136 | 8 | S-1699 | EP ELECT T |
| " | 28 | 2129-2136 | 8 | S-1700 | EPD INPUT I |
| " | 34 | 2129-2136 | 8 | S-1701 | EP +60V |
| " | 40 | 2129-2136 | 8 | S-1702 | LOG AMP T |
| " | 46 | 2129-2136 | 8 | S-1703 | EP -15V |
| " | 52 | 2129-2136 | 8 | S-1704 | EP +10V |
| " | 58 | 2129-2136 | 8 | S-1705 | EPD +6V |
| " | 64 | 2129-2136 | 8 | S-1706 | EPD +3V |
| " | 70 | 2129-2136 | 8 | S-1707 | EP -3V |
| " | 76 | 2129-2136 | 8 | S-1708 | EP -6V |
| " | 82 | 2129-2136 | 8 | S-1709 | EP -10V |
| " | 00 | 2187 | 1 | S-1710 | EP BUS PAR - NORMAL, ERROR |
| " | 05 | 2129-2136 | 8 | S-1711 | EPD SCAN 3 |
| " | 09 | 2131-2136 | 6 | S-1712 | EPD SCAN 4 |
| " | 23 | 2129-2136 | 8 | S-1713 | EPD MEM CS |
| " | 35 | 2129-2136 | 8 | S-1714 | EPD LEMMS D |
Each GLL telemetry frame shall contain a S/C time field. The SCLK shall have the characteristic that it can be directly used to determine time, identify all measurements, and to correlate events to within the time resolution of the S/C clock.
The SCLK shall mark the first bit of the frame synchronization code time and shall represent the time interval in which the CDS collected the instrument data contained within the frame. The SCLK is shown in Figure 5 and is described below.
Figure 5. Spacecraft Clock (SCLK)
Real-Time Image Count (RIM). This field is a 24 bit counter which shall be incremented each 60 2/3 s (corresponding to a real-time image cycle). This clock shall keep unambiguous account of time for 32 years. The starting value of the counter shall be initialized at launch and shall not be reset after launch except from the ground after an interruption of power to the CDS memories. The maximum value of the SCLK shall not roll over until attaining the value 16777215.
Mod 91 Count (MOD91). The MOD91 counter is an 8 bit counter which shall be incremented once every 2/3 s. This field shall range in value from 0 through 90, with 0 corresponding to the start of the real-time solid state imaging cycle. This field shall increment by one every LRS frame.
Telemetry mode changes shall occur synchronously with (1) the rollover of the MOD91 count from 90 to 0 and (2) incrementing the RIM by 1.
Mod 10 Count (MOD10). The MOD10 counter is an 8 bit counter which shall be incremented once each 66 2/3 msec. This field shall range from 0 through 9, with the change to zero synchronous to the incrementing of the MOD91 count. This field shall increment by 1 for each frame transmitted or recorded at a telemetry rate greater than 7.68 kb/s. The MOD10 count is synonymous with the Real-Time Interrupt (RTI) in the CDS.
Mod 8 Count (MOD8). The MOD8 counter is an 8 bit counter which shall be incremented once each 8 1/3 ms. The field shall range from 0 through 7. With the change to 0 synchronous to the incrementing of the MOD10 count.
This field shall normally be zero in any frame being created at telemetry rates less than or equaling 115.2 kb/s. For those frames being routed to the DMS at rates exceeding 115.2 kb/s, the counter shall increment by one for each frame placed onto the DMS.
Next: 3. EPD Subsystem Telemetry
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Updated 8/23/19, Cameron Crane
QUICK FACTS
Mission Duration: Galileo was planned to have a mission duration of around 8 years, but was kept in operation for 13 years, 11 months, and 3 days, until it was destroyed in a controlled impact with Jupiter on September 21, 2003.
Destination: Galileo's destination was Jupiter and its moons, which it orbitted for 7 years, 9 months, and 13 days.