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Astro 331 Data Handling—Intro Lesson 23

Astro 331 Data Handling—Intro Lesson 23. Spring 2005. Data Handling—Intro Objectives. Objectives Objective 1. Know the driving requirements for the data handling subsystem (DH) Objective 2. Know the functions and components of the DH subsystem

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Astro 331 Data Handling—Intro Lesson 23

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  1. Astro 331Data Handling—IntroLesson 23 Spring 2005

  2. Data Handling—IntroObjectives Objectives • Objective 1. Know the driving requirements for the data handling subsystem (DH) • Objective 2. Know the functions and components of the DH subsystem • Objective 3. Be familiar with the DH subsystem of example spacecraft Reading • SMAD Chapter 11.3 Lesson 23

  3. Data Handling—IntroDriving Requirements • Two main system requirements • Receives, validates, decodes, and distributes commands to other spacecraft systems • Gathers, processes, and formats spacecraft housekeeping and mission data for downlink or use by an onboard computer. • The data handling (DH) subsystem has probably the least defined driving requirements of all subsystems and is usually designed last • Based on the complexity of the spacecraft and two performance parameters: 1) on-board processing power to run bus and payloads and 2) storage capacity for housekeeping and payload data • Meeting requirements is a function of available flight computer configurations Lesson 23

  4. Data Handling—IntroDriving Requirements • System level requirements and constraints • Satellite power up default mode • Power constraints • Mass and size constraints • Reliability • Data bus requirements (architecture and number of digital and analog channels) • Analog interface module derived requirement • Total-dose radiation hardness requirement • Single-event charged particle hardness requirement • Other strategic radiation requirements (EMP, dose rate, neutron flux, operate through nuclear event, etc.) • Software flash upgradeable Lesson 23

  5. Data Handling—IntroFunctions • Subsystem known by a variety of names • TT&C: Telemetry, Tracking, and Control (or Command) • TTC&C: Telemetry, Tracking, Command, and Communication • TC&R: Telemetry, Command and Ranging • C&DH: Command and Data Handling • CT&DH: Command, Tracking and Data Handling • Functions • Receives, validates, decodes, and distributes commands to other spacecraft systems • Gathers, processes, and formats spacecraft housekeeping and mission data for downlink or use by an onboard computer. Lesson 23

  6. Data Handling—IntroFunctions Lesson 23

  7. Data Handling—IntroFunctions • CT&DH Functions: • Aid in orbit determination (tracking) • Command S/C (command) (concerned with the uplink) • Provide S/C status (telemetry) (concerned with the downlink) • Gather and process data • Data handling • Make payload data available (telemetry) (concerned with the downlink) • Sometimes, the payload will have a dedicated system rather than using the bus • CT&DH functions often performed by OBC (On-Board Computer) • Comm Functions: • Deals with data transmission concerns (encryption, modulation scheme, antenna characteristics, medium characteristics) These will be discussed in Comm lessons. Lesson 23

  8. Data Handling—IntroFunctions—Command Handling • Commands may be generated by: • The Ground Station • Internally by the CT&DH computer • Another subsystem • Types of commands • Low-level On-Off: reset logic switches in SW (computer controlled actions) • High-level On-Off: reset mechanical devices directly (i.e. latching relays, solenoids, waveguide switches, power to Xmitter) • Proportional Commands: digital words (camera pointing angle, valve opening size) Lesson 23

  9. Data Handling—IntroFunctions—Data/Telemetry Handling • Housekeeping: • Temps • Pressures • Voltages and currents • Operating status (on/off) • Redundancy status (which unit is in use) • … • Attitude: might need to update  4 times/sec • Payload: case-by-case payload health and payload data Lesson 23

  10. Data Handling—IntroFunctions—Command/Data Packet - synchronization, address (ID), command/data, and parity From Spacecraft Systems Engineering, by Fortescue and Stark Lesson 23

  11. Data Handling—IntroComponents • On-board computer/flight computer module • Central Processing Unit (CPU) • Data storage (memory) • SRAM CPU registers • SRAM L2 cache • SRAM/DRAM main memory • Direct memory access (DMA) handling • BIOS boot up/boot loader • External interfaces • Direct input/output (I/O) lines • RS-232 serial (asynchronous or synchronous) • IEEE 1284-B parallel • Ethernet • Interface module • Analog to digital conversions (op amps) • Discrete digital channels Lesson 23

  12. Data Handling—IntroComponents Lesson 23

  13. In Space Today: 78 Satellites 261 Computers Hours on Orbit: 16 Bit - 1.8 Million RAD6000 - 1.1 Million 6/12/00 Lesson 23 16 Bit RAD6000 RAD750 6/12/00

  14. Data Handling Subsystem—IntroFalconSAT-3 DH • Data Handling unit of FS-3 is a SpaceQuest IFC-1000 Lesson 23

  15. Data Handling Subsystem—IntroFalconSAT-3 DH Lesson 23

  16. Data Handling Subsystem—IntroFalconSAT-3 DH • Functional Requirement: • 1.4.3.1 The SV shall collect telemetry, process commands and perform routine housekeeping data processing tasks via stored or uplinked software. • Detailed Requirements: • 9.5.1 The IFC Tray shall provide data handling & storage and modems, together with command and control handling and verification, to support the mission. • 9.5.2 Processor: The IFC shall use the NEC V-53A CMOS 16-bit microprocessor with a 29.5 MHz crystal oscillator. • 9.5.3 RAM: The IFC shall have 16 Mbytes of internal Static RAM plus 1 Mbyte of error-corrected SRAM implemented in 3 Mbytes of physical SRAM. This memory is checked and corrected on every read and "washed" periodically via the operating system to correct and repair radiation-induced single event upset bit errors. • 9.5.4 FLASH: The IFC shall have 16 MBytes of FLASH memory. Lesson 23

  17. Data Handling Subsystem—IntroFalconSAT-3 DH • Detailed Requirements: • 9.5.5 Software: The SCOS operating system shall be ported to the IFC by TDB . (Note: AMSAT is planning to run SCOS on the IFC prior to the FalconSAT-3 mission) • 9.5.6 Software Development Facility: A TBD IFC-1000 will be used for software development, test and simulation. • 9.5.7 Power Line: The IFC shall use a single regulated +3.3V power line. • 9.5.8 Input Power: The IFC module shall require an input power of 0.3 Watts with 29.5 MHz Crystal during normal operations. • 9.5.9 Digital I/O: The IFC shall support 40 individually addressable latched digital I/O lines for general purpose external communication and control; 2 dedicated SPI interfaces with two select lines each, for two A to D multiplexers and two modem ports; 1 I2C interface; one RS-232 interface; 7 digitally-controlled, open-drain FETs for high current switch control (up to 600 mA each). Lesson 23

  18. Data Handling Subsystem—IntroFalconSAT-3 DH • Detailed Requirements: • 9.5.10 IFC Tray Thermal Constraints: The survival temperature range of the IFC tray shall be between -30 C to +60 C; the nominal operating temperature range shall be between -10 C to +50 C (TBR). • 9.5.11 The IFC shall have one port for external RAM disk, addressing up to 27.5 MB of external RAM • 9.5.12 The IFC shall have 256K x 8 boot loader ROM that is partitioned into two 128K spaces to allow a restart from two separate boot programs if reset by the fire-code state machines. • 9.5.13 The IFC shall have a RS-232 interface that allows an external computer to directly upload and exercise flight software during pre-flight system tests. This interface is switched off when not in use, to conserve power. The on-board modem has two transmit channels and six receive channels with independent operating speeds, and the system is capable of full simultaneous multiplex operation. Two transmitters and six receivers can be connected to the board. The modems use Gaussian Minimum Shift Keying (GMSK). GMSK occupies narrow bandwidth, and the modems have low component count and low power consumption. • 9.5.14 Each IFC shall have 2 fire code ICs for remote reset. The codes will be chosen and burned by the USAFA into ICs before the end of September 2003 for installation by SpaceQuest. Lesson 23

  19. Data Handling Subsystem—IntroFalconSAT-3 DH • Detailed Requirements (supporting interface module): • 9.9.3 Analog Inputs: The A/D telemetry board shall support at 12 bit resolution, 41 high impedance analog telemetry inputs in three groups; one group of three, one group of nine, one group of twenty-nine. Input voltage standard range of 0V to +4V in uni-polar mode, or -2 to +2V in bipolar mode. There are 14 thermistor inputs for 10K/25C thermistors such as the YSI44006. • 9.9.4 The A/D telemetry board shall provide 10 control lines: 4 digital lines are for ADC control and retrieval via SPI and 6 MUXing lines for input selection. • 9.9.5 A/D Conversion: The A/D telemetry shall support 12-bit Analog to Digital Conversion over the range of 0 to 4 Volts. • 9.9.6 Input power: The A/D telemetry board shall require 15 mA @ 3.3 V (approxately 50 mW) during normal operations (TBR).. • 9.9.7 PIM Tray Thermal Constraints: The survival temperature limits for the PIM Tray shall be between -30 C to +60 C; the nominal operating limits shall be between -10 C to +50 C. • 9.9.8 PIM Tray dimensions shall be 23.6 x 23.6 x 2.5 cm. • 9.9.9 The mass of the PIM Tray shall be 0.72 kg, including 0.52 kg for the A/D board plus tray and 0.2 kg for the PIB. Lesson 23

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