ARISSat-1 Critical Design Review Orlando, Feb 15, 2010 IHU Joseph Julicher

Feb 15, 2010ARISSat-1 CDR2 Introduction Internal House Keeping & Mission Management Scope –Manage Voice messages on SD card –Camera control & image capture –Telemetry Gathering –BPSK & Morse Generation –Experiment Scheduling & data capture –Measure Analog Thermistors

Feb 15, 2010ARISSat-1 CDR3 Requirements FM Mode Missions –Voice Messages from SD card –SSTV from camera subsystem –Voice Telemetry Experiment Scheduling –Activate experiments on schedule –Save experiment data for transmission BPSK Telemetry Encoding –Telemetry and Experiment Data Execute Commands from Command Decoder

Feb 15, 2010ARISSat-1 CDR4 I2CI2C 485 Design CPLDSD Card Experiment Power Supply Communications SPI I2CI2C Parallel Video Capture SPI CPU SDX Communications SDRAM Command Decoder 485

Feb 15, 2010ARISSat-1 CDR5 PCB Assembly

Feb 15, 2010ARISSat-1 CDR6 Video NTSC Image Captured to 16MB SDRAM Software in CPU triggers Capture Software in CPU analyzes image with CPLD assistance to keep the best ones. CPU gets image data via Parallel port SDRAM managed by CPLD Images Transmitted via Slow Scan Television –Robot-36 format, 36 seconds to transmit image

Feb 15, 2010ARISSat-1 CDR7 SDX Communications Communications with SDX Hardware via SPI. Every millisecond, IHU & SDX exchange data. SDX Health is monitored by IHU via data checksum. BPSK, Morse and FM Audio data sent to the SDX.

Feb 15, 2010ARISSat-1 CDR8 SD Card Commemorative messages stored on the SD card as.wav files. SD card communicates via SPI FAT file system driver provided by open source Tiny Fat. Limited Backup messages stored in CPU Flash memory if SD card Fails. Voice Telemetry female voices from SD card. Male voices from Flash if SD failure.

Feb 15, 2010ARISSat-1 CDR9 Power Management I 2 C communications to Power Supply Unit (PSU). I 2 C failure will result in Power Cycle –(up to 3 consecutive cycles then all subsystems will turn on forever) Power Telemetry read from PSU. Power Management Commands sent to PSU.

Feb 15, 2010ARISSat-1 CDR10 Experiments Up to 4 Experiment channels available. Original spec for Experiments to be powered every 90 minutes for 2 minutes. 2 seconds for data transfer available after powered period. Up to 2k of data per experiment is stored for telemetry broadcast.

Feb 15, 2010ARISSat-1 CDR11 Command Decoder Interface Receives most commands from command decoder Aborts missions in progress to process commands Sends Audible and CW acknowledgements of Command Reception before executing Command Decoder Reset command enforces by power cycling system thru Safety Timers

Feb 15, 2010ARISSat-1 CDR12 Thermistors 8 Channels of Thermistor inputs Multiplexed on two ADC channels

Feb 15, 2010ARISSat-1 CDR13 Safety Considerations No Astronaut safety concerns in IHU. Mission failure concerns are: –Loss of PSU communications will eliminate power management forcing higher battery consumption. –Loss of SD card will eliminate most commemorative messages. –Loss of Experiment communications will eliminate experiment mission.

Feb 15, 2010ARISSat-1 CDR14 Verification Hardware verification complete –Images captured and sent –Communicates with SDX –Communicates with PSU –Temperature readings taken Ongoing verification as software is refined

Feb 15, 2010ARISSat-1 CDR15 Status Software still under development –Power modes not implemented –All telemetry data not yet gathered –Image management incomplete Major features complete –Sends FM Missions –Sends SSTV –Sends CW –Sends Experiment data