USAFA Department of Astronautics I n t e g r i t y - S e r v i c e - E x c e l l e n c e Astro 331 Data Handling—Intro Lesson 23 Spring 2005

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 2 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 Objective 3. Be familiar with the DH subsystem of example spacecraft Reading SMAD Chapter 11.3

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 3 Data Handling—Intro Driving 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

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 4 Data Handling—Intro Driving 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

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 5 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. Data Handling—Intro Functions

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 6 Data Handling—Intro Functions

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 7 Data Handling—Intro Functions 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.

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 8 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) Data Handling—Intro Functions—Command Handling

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 23 9 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 Data Handling—Intro Functions—Data/Telemetry Handling

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson synchronization, address (ID), command/data, and parity From Spacecraft Systems Engineering, by Fortescue and Stark Data Handling—Intro Functions—Command/Data Packet

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson 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 Data Handling—Intro Components

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling—Intro Components

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson In Space Today: 78 Satellites 261 Computers Hours on Orbit: 16 Bit Million RAD Million 6/12/00 16 BitRAD6000RAD750

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling Subsystem—Intro FalconSAT-3 DH Data Handling unit of FS-3 is a SpaceQuest IFC-1000

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling Subsystem—Intro FalconSAT-3 DH

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling Subsystem—Intro FalconSAT-3 DH Functional Requirement: The SV shall collect telemetry, process commands and perform routine housekeeping data processing tasks via stored or uplinked software. Detailed Requirements: The IFC Tray shall provide data handling & storage and modems, together with command and control handling and verification, to support the mission Processor: The IFC shall use the NEC V-53A CMOS 16-bit microprocessor with a 29.5 MHz crystal oscillator 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 FLASH: The IFC shall have 16 MBytes of FLASH memory.

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling Subsystem—Intro FalconSAT-3 DH Detailed Requirements: 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) Software Development Facility: A TBD IFC-1000 will be used for software development, test and simulation Power Line: The IFC shall use a single regulated +3.3V power line Input Power: The IFC module shall require an input power of 0.3 Watts with 29.5 MHz Crystal during normal operations 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).

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling Subsystem—Intro FalconSAT-3 DH Detailed Requirements: 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) The IFC shall have one port for external RAM disk, addressing up to 27.5 MB of external RAM 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 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 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.

I n t e g r i t y - S e r v i c e - E x c e l l e n c e 3 Jan 05Lesson Data Handling Subsystem—Intro FalconSAT-3 DH Detailed Requirements (supporting interface module): 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 YSI 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 A/D Conversion: The A/D telemetry shall support 12-bit Analog to Digital Conversion over the range of 0 to 4 Volts Input power: The A/D telemetry board shall require V (approxately 50 mW) during normal operations (TBR) 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 PIM Tray dimensions shall be 23.6 x 23.6 x 2.5 cm 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.