C

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CDH
Philip Luers NASA/GSFC Code 561 August 16-17, 2005
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Requirements Flow-Document Tree
CRaTER EICD 431-ICD-000094
LRO ELV Mission Specification RLEP-LRO-P40
LRO Requirements Document 431-RQMT-00011
MRD
Diviner EICD 431-ICD-000095
LRO Mechanical Environments and Verification
Requirements 431-RQMT-000012
LRO ELECTRICAL SPEC 431-SPEC-00008
LAMP EICD 431-ICD-000096 LAMP DICD 431-ICD-000106
LRO Radiation Requirements 431-RQMT-000045
LRO PSE ICD 431-ICD-000018
LEND EICD 4301-ICD-000097
THERMAL SYSTEM SPEC 431-SPEC-000091
LOLA EICD 431-ICD-000098
CDH Requirements 431-RQMT-000168
COMMUNICATION SYSTEM REQUIREMENTS 431-REQT-000137
LROC EICD 431-ICD-000099 LROC DICD 431-ICD-000109
SpaceWire SPEC 431-SPEC-000103
LRO Flight Software Requirements 431-REQT-000139
1553B Bus Spec 431-SPEC-000102
CDH
FSW
LVPC REQs Section 6
Chassis REQs Section 14
SBC REQs Section 7
HK/IO REQs Section 8
Thermal REQs Section 9
SSR REQs Section 10
KaComm REQs Section 11
Backplane REQs Section 13
S-Band REQs Section 12
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements to all CDH
Sub-Assemblies
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-033 1.3.3.3 Electrical Interfaces CDH shall comply with the LRO Electrical System SPEC 431-SPEC-000008. Each Board has the electrical breakdown documented in Section 3 of its requirements. Power Consumption and Inrush Current are documented.
MRD-034 1.3.3.4 Thermal Interfaces CDH shall comply with the LRO Thermal System Specifications 431-SPEC-000091 Box meets these requirements. Section 5 of each board details additional thermal methods taken (i.e. heat sinks) to meet LRO Thermal requirements.
MRD-068 1.4.12 EEE Parts Radiation CDH shall meet the requirements of the LRO Radiation Requirements Doc 431-RQMT-00045 Section 1.1 of each board details additional radiation requirements and mitigation where necessary.
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements to Single
Board Computer (SBC)
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-086 3.5.4.1 FSW and ACS SW Processing Storage The SBC shall provide TBD MIPS processing platform for FSW and ACS SW. This value is based on a 5 second average CPU utilization calculation as required in the GFSC-STD-1000 pg 60 and table 3.07-1.
MRD-108 3.5.4.2 Boot Code Storage The SBC shall provide minimum 64KB of non-reprogrammable (in-flight) non-volatile storage of SUROM boot code. To mitigate the potential EEPROM Radiation and soft-bit issues, PROM is used for SUROM boot code.
MRD-108 3.5.4.3 Application Code Storage The SBC shall provide minimum 4MB of non-reprogrammable (in-flight) non-volatile storage for EEPROM application code. To mitigate the potential EEPROM Rad and soft-bit issues, the 4MB EEPROMs are used to store 2 identical flight application code images with a hardware switchover option.
MRD-108 3.5.4.4 Executable Code Storage The SBC shall provide minimum 20MB of volatile storage for SRAM executable code storage. Storage for applications code, data tables, data.
MRD-109 3.5.1.1.2 1553B Bus Controller The SBC shall operate as Bus Controller (BC) for 1553B as a default. Designed to operate as either BC or RT on 1553B.
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Data Volume
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-118 3.5.4.5 SBC SRAM Data Storage The SBC shall provide a minimum of 20 MB memory for storage of housekeeping data whenever the SSR is off. Whenever the Solid State Recorder is turned off, all spacecraft and housekeeping data shall be recorded in the SBC. SBC shall have additional SRAM for data storage.
MRD-037 3.5.7.1 SSR Data Storage Normal Operations The SSR shall provide at least 400Gbits End Of Life (EOL) of memory capacity for incoming data files for science data and housekeeping data collection. SSR Storage requirement (Based on 4 ground station passes back to back, each 45 minutes long with the time between last and first pass is 1044 minutes). SSR needs to store 6.4 Mbps (6.4x10e6) average data rate (includes all instruments and S/C engineering) for at least 1044 minutes. Gives approximately 391 Gbits (3.91x10e11) (assuming max LROC data, 16 NAC pairs per orbit). Also based on downlink rate of 125 Mbps (1.25x10e8).
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Networks
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-035 3.5.1.1 Low Speed Bus (LSB) 1553B CDH shall utilize a MIL-STD-1553B network per Electrical System Spec 431-SPEC-00008 to interconnect subsystems and instruments for telemetry, commanding, and low speed instrument data. Industry standard interface simplifies interfaces, improves flexibility and supports future growth.
MRD-109 3.5.1.1.2 1553B Bus Controller The SBC shall operate as Bus Controller (BC) as a default. MRD Level 2 requirement.
MRD-035 3.5.1.1.3 LSB Scheduling The CDH shall initiate predictable transactions on the LSB according to a pre-planned schedule accurate to /-5ms and synchronized to the 1 Hz pulse. Ensures reliability of data transfer.
MRD-036, MRD-038 3.5.1.2 High Speed Bus (HSB) SpaceWire CDH shall utilize a SpaceWire network per LRO SpaceWire SPEC 430-SPEC-000103 to interconnect subsystems and instruments for telemetry, commanding, and high rate data, maximum rate of 125 Mbps (125x106). Industry standard interface simplifies interfaces, improves flexibility and supports future growth. Downlink schedule and data volume drive the data rate.
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Telemetry
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-112 3.5.6.1 CDH Comm Telemetry Encoding CDH Comm System shall provide telemetry encoding options i.e. Reed Solomon (RS), Bi-Phase-L, NRZ-L or NRZ-M. All are supported by ground stations.
MRD-110 3.5.6.2 CDH CFDP CDH Comm system shall support CFDP. Meets FSW and Comm requirements per LRO 431-REQT-000137.
MRD-028, MRD-113 3.5.6.3 CDH Comm Ground Test CDH Comm system shall provide a hardline interface for ground test through the spacecraft umbilical. Method for integration and test without using RF components.
MRD-110, MRD-123 3.5.6.5.2 S-Band Downlink Telemetry CDH S-Band shall support CCSDS downlink telemetry at a maximum rate of 2.186 Mbps (2.186x106). Science data and housekeeping data source. Meets Comm requirements per LRO 431-REQT-000137
MRD-110, MRD-124 3.5.6.4.1 Ka-Comm Downlink Telemetry CDH Ka-Comm shall support CCSDS downlink telemetry at a maximum rate of 125 Mbps (125x106). Science data and housekeeping data source including TLM encoding. Meets Comm requirements per LRO 431-REQT-000137
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Commands
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-119, MRD-122 3.5.6.5.1 CDH S-Band Telecommand CDH shall support CCSDS telecommands at a maximum rate of 4 Kbps (4x103). Consistent with requirements of flight software and communications. CDH can support up to 16Kbps (1.6x10e4).
MRD-111 3.5.6.5.1.1 CDH Hardware Decoding CDH shall perform hardware decoding of critical commands. Generate 5 RS422 outputs. Method for recovery from anomalous conditions. Ongoing safe-mode and recovery scenario studies. CDH can support up to 8 outputs.
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Timing
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-042 3.5.2.2, 1.3.4.1.1 Barker Time CDH shall record the time of receipt of last ground telecommand. To ensure reliability of communication link to the ground station.
MRD-068 3.5.2.1 Watchdogs and External Resets The CDH shall provide and control a watch dog timer. To prevent a software continuous loop failure.
MRD-042 1.3.4.1.2 Other Errors The timing error due to other error sources shall be less than 1 ms. The sources of error (clock, stability, accuracy of distribution, latency of timetick, transmit time) Must be less than 3 ms knowledge requirement.
MRD-043 1.3.4.2.1 Oscillator Drift The onboard oscillator shall not drift by more than 100 ms in 24 hours over the operational temperature range. Maintains ability to execute stored commands within 100 ms of desired UTC time with an accuracy of 1ms.
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Timing
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-157 1.3.4.2.2 Oscillator Stability The oscillator stability shall meet the timing requirements in Section 1.2.1.1 in the presence of the measurement errors described in Section 1.2.1.2. Selected an oscillator with a frequency stability of 10 ppb.
MRD-043 1.3.4.2.3 Time Correction Accuracy The CDH shall provide a mechanism to correct Orbiter time to within 100 ms of UTC time. Ensures maintenance of accuracy.
MRD-114 1.3.4.3 MET Counter The CDH shall provide a Mission Elapsed Timer (MET) that cannot be adjusted. Standard design reduces the design complexity and meets the requirements.
MRD-042 1.3.4.3.1 MET Resolution The MET counter shall have a resolution of 15 microseconds. For accurate commanding. CDH shall utilize a 16-bit sub-second counter .
MRD-043 1.3.4.3.2 MET Rollover The MET counter shall be capable of operating for 5 years without rollover. No discontinuities wanted. The use of a 28-bit second counter supports rollover not occurring for 8.5 years.
MRD-043 1.3.4.4 Pulse Per Second The CDH shall provide a 1 Hz pulse as required by the instruments. For timing and synchronization of commands.
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Flow Down KeyRequirements for Instrument
Interfaces
Level 2 Req. Level 3 Requirements Concept/Compliance
Paragraph Requirement
MRD-117 1.3.4.5 , 3.5.1.2 2.3.13 2.3.5 RS422 Serial LSB CDH shall provide an asynchronous 38400 baud RS422 Serial LSB for telemetry and commanding to the LAMP instrument. All telecommands and time messages shall be transmitted to LAMP via an asynchronous 38400 baud RS422 Serial LSB LAMP shall transmit science data using LVDS compliant chips. LAMP/Pluto heritage. Meets LAMP DICD 431-ICD-000106.
MRD-116 MRD-117 1.3.4.5, 2.3.1.3 Time Message RS422 Serial LSB CDH shall provide the LAMP instrument a time message via RS422 serial LSB. Meets LAMP DICD 431-ICD-000106.
MRD-035, MRD-116 1.3.4.5, 2.1.2.1, 2.2.2.1, 2.4.2.1, 2.5.2.1 Time message 1553B CDH shall provide the following instruments a time message via 1553B CRaTER, Diviner, LEND, and LOLA. Meets Instrument ICDs.
MRD-036, MRD-116 1.3.4.5, 2.6.2.1 SpaceWire Time Code Message CDH shall provide the LROC instrument a Time Code Message every 1 Hz via SpaceWire. Meets LROC DICD 431-ICD-0000109.
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LRO CDH Architecture Block Diagram
NAC1
WAC
NAC2
Mini- RF
L A M P
LEND
D ivi ner
L O L A
C R A T E R
SUBSYSTEMS (ACS, PSE, PRO/DEP)
Hi-Rate Tlm 125Mbps (Max.)
S-Xpndr
LROC
HGA
Ka-Xmtr
SpaceWire FPGA
SpaceWire FPGA
32 Mbps
HGA Gimbals
38.4Kbps (UART)
Serial IF
8 to 32Mbps (Max.)
1553B
Low-Rate Tlm 2Mbps Max Command 4Kbps
1Mbps
5 Heater out Unsw.28V
2.186 Mbps Max. (HK Downlink)
Sw. 28V (Heater)
Sw. 28V (Ka-Comm)
2.186 Mbps Max. (LAMP Tlm)
Sw. 28V (SSR)
I/O
125 Mbps (Science Downlink)
UnSw. 28V (S-Comm)
50 Mbps Max. (Tlm)
Unsw. 28V
1PPS
SSR
HK/IO
Ka- Comm
S- Comm
Thermal Card
BAE SpaceWire ASIC
1553 Summit
BAE SpaceWire ASIC
SpaceWire FPGA
SpaceWire FPGA
SpaceWire FPGA
LVPC
1553 Summit
RAD750 SBC
( A)
(B)
28V Power
/-15V, 5V, 3.3V (A)
SpaceWire (HSB)
3.3V (B)
Backplane (Power POR)
1553B (LSB)
CDH
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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Verification

• Analysis
• ? FPGA/ASIC (Worst-case Timing Simulation, Test
  Benches)
• ? Board-level (Test Benches, Throughput
  Performance, Signal Integrity)
• Testing
• ? Component
• Radiation (1.5V Linear Regulator, ACTEL FPGA AX
  series, Micron SDRAM dies)
• ? Subsystem
• Board-level (BB, ETU FLT)
• Box-level (ETU FLT)
• ? Environments
• EMI/EMC, Thermal Vacuum, Vibration (FLT)
• ? System IT
• FLATSAT Subsystems Electrical Interface Testing
  (ETU)
• Spacecraft (FLT)
• Orbiter EMI/EMC, Thermal Vacuum, Vibration,
  Acoustic (FLT)

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Lunar Reconnaissance Orbiter (LRO)CDH System
Level 2 Summary

• CDH Level 2 Requirements are defined, and are
  traceable to LRO requirements.
• ? CDH architecture meets these requirements.
• All CDH requirements have been captured in a
  requirements document.
• ? Requirements and technical resources have been
  allocated to assemblies.
• CDH Requirements are in the process of
  submission to CM for release.
• Key Interface Requirements are defined.
• ? Have initiated ICD-Level interface definition,
  some TBDs pending.
• Key Trade Studies and Analyses have been
  completed (Data Volume, 1553B, SpaceWire)

CDH is ready to continue Preliminary Design.