Transcript Document

AMSAT OSCAR-E,
ADCARS, and "Eagle"
Presented by
Richard M. Hambly (W2GPS)
AMSAT-DC MEETING AND SPACE SEMINAR
Maryland-DC area AMSAT Meeting and Space Seminar
Sunday, May 5, 2002, 13:00-17:00 EDT
NASA Goddard Space Flight Center
Greenbelt, Maryland
W2GPS, May 5, 2002
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AMSAT OSCAR-E,
"Eagle", and ADCARS
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AMSAT OSCAR-E is a
new LEO satellite from
AMSAT-NA.
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ADACRS is “Advanced
Data Communications for
the Amateur Radio
Service
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“Eagle” is a new HEO
satellite from AMSAT-NA.
W2GPS, May 5, 2002
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AMSAT OSCAR-E (AO-E)
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AMSAT-NA is back in the satellite
business!
» 12 years since AMSAT-NA built and
launched the original Microsats, AO-16,
DO-17, WO-18, and LO-19 in 1990.
» 8 years since AMRAD-sponsored AO-27
was launched in 1993.
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AMSAT OSCAR-E is a new Low Earth Orbit (LEO) satellite
AMSAT is returning to the practice of designating LEO satellites
by sequential characters.
» This was last done for AMSAT OSCAR-D, which became AMSAT
OSCAR-8 after launch and commissioning.
» AMSAT didn't use letters for the first four Microsats
» Phase 3 series started again with “A”.
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Space and power are available for one or more optional
payloads that will be provided by AMSAT volunteers.
W2GPS, May 5, 2002
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AO-E Introduction
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A Microsat class spacecraft weighing
approximately 10 kg.
Consists of five solid aluminum trays,
each with four walls and a bottom
stacked to form approximately a 10-inch
cube structure.
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Dick Daniels W4PUJ at
SpaceQuest 28_Feb-2002
W2GPS, May 5, 2002
Six solar panels attach to each of the
six sides.
Several antennas protrude from the top
and bottom surfaces.
Similar to AMSAT’s original Microsats
(AO-16, DO-17, WO-18, and LO-19).
They were followed by the
descendents of that legacy, including
IO-26, AO-27, MO-30, and SO-41.
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AO-E Block Diagram
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Four VHF receivers
One Multi-Band Multi-Mode Receiver
Two UHF transmitters
Six modems
Flight computer
RAM disk
Batteries
Battery charger and voltage regulators
Wiring harness
RF cabling
RF switching and phasing networks
56 channels of telemetry
Magnetic attitude control
W2GPS, May 5, 2002
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AO-E Core Subsystems
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Physical structure
Attitude control
Central processor hardware
Spacecraft flight software
Power generation and
distribution
Command and control
A basic set of receivers,
transmitters and antennas
Space for optional payloads
W2GPS, May 5, 2002
AMSAT Board visits SpaceQuest, 20-Apr-2002
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AO-E Physical structure
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A stack of five machined aluminum modules,
each 9.5” x 9.5”.
The height of each module is adjustable up
to a total of 9.5 inches.
Nominal useful internal area is approximately
8 inches x 7.5 inches.
RF cables and a wiring harness carry power,
inter-module data, telemetry, and control
signals.
Four machined rods running the height of the
spacecraft bolt the assembly together.
Passive thermal control system
Almost all of the satellite’s surface area is
covered by solar cells.
The remaining surface area is covered with
thermal absorbing and reflective tape.
A separation mechanism.
W2GPS, May 5, 2002
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AO-E Attitude Control
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Two magnetic rods that align the satellite’s vertical axis with the
Earth’s magnetic field.
» Allows one end of the satellite to point generally towards the earth.
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Four hysteresis damping rods that control the satellite spin rate.
Reflective/absorptive tape that cause the satellite to rotate about its
Z-axis as a result of solar photon pressure.
» Solar-induced spin averages out the thermal load on the satellite.
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Limitations
» The satellite makes two rotations per orbit
resulting in one face favoring the Northern
Hemisphere and the opposite face favoring
the Southern Hemisphere.
» The Earth-pointing direction is on the order
of ±20 degrees in the temperate zones,
varying with orbital inclination.
W2GPS, May 5, 2002
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AO-E Central Processor Hardware
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Memory
Boot EPROM
Boot TMR
EPROM
1 MByte
EDAC
1 MByte
TMRByte
EDAC
Dual 128K
Six -Channel
Flight-proven, low-power
FSK Modem
NEC V53A processor clocked
at 29.412 MHz.
RAMDISK
CMOS Digital I/O
FPGA Logic
EPROM has redundant
16M Byte
Open-Drain NFETs
sections.
Main memory system is errorFLASH
detecting and correcting
SPI Ports
4MByte
– 32MByte
16MByte
(EDAC) using bit-wise triple
mode redundancy (TMR).
16Mb RAMDisk for bulk data storage.
16Mb Flash memory for rapid re-booting of the OS and applications.
Six (6) GMSK modems - 600 bit/s to 115.2 kbit/s.
Eight (8) open collector N-channel FETs provide power switching.
Serial Peripheral Interface (SPI) bus links telemetry boards to CPU.
W2GPS, May 5, 2002
V53A @ 29.4 MHz
DMA Interrupts
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AO-E Spacecraft Flight Software
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Boot loader
» File Transfer
» Tx Scheduling and Power Monitoring
» Supervisor Task Loader and Monitoring
» verifies satellite health and loads the
operating system
» Sends acknowledge beacons
 Mission Software provides complete
» Uploads new software
control over all aspects of the satellite
» Downloads memory locations
» Advanced Task Supervisor
» Peak and Poke memory and I/O
» TX and RX multiplexing and control
» Loads software from FLASH or error» Telemetry monitoring, storage and
detecting and correcting memory
reporting
(EDAC)
» RAMDISK management
» Executes OS by command or timer
» Communications protocol
 Operating System
» Scheduling for regional satellite access
» Moved from EPROM to RAM by the
» Magnet torquer and IR attitude control
boot loader
» Optional experiment control
» Detailed telemetry reporting
» Power system control
» Control of transmitters and receivers
» Minimal attitude control
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OS Support Tasks
» Memory file manager
W2GPS, May 5, 2002
A new antenna design on the
roof at SpaceQuest, 20-Apr-2002
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AO-E Power Generation
and Distribution
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Battery Control Regulator (BCR)
converts solar panel power to system
power, and manages battery charge and
protection.
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Switching design with 89% efficiency.
Operates autonomously.
CPU can fine-tune default parameters.
Multiple switched 8-V lines for high power
applications such as Transmitters.
» 3.3-V and 4.6-V switching regulators, each
with 250 mA output, with multiple switched
and unswitched outputs.
» Separation-switch circuitry.
» External connection port with two levels of
separation switch override.
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GaAs Solar Panels on all sides of AO-E
produce about 16 volts at a minimum
efficiency of 19%.
Battery is six NiCd 4.4 Ah cells with a
nominal battery voltage of 8 V DC.
W2GPS, May 5, 2002
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AO-E Command and Control
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Bootloader communicates with AO-E’s
bootloader to upload code changes, or to
load and execute the OS and tasks.
Housekeeping communicates with each of
the tasks onboard the satellite. Its primary
use is to configure the satellite.
Telemetry Gathering and Reporting
downloads and displays satellite health
information.
Mark Kanawati N4TPY with
“FlatSat” 20-Apr-2002
Note: each of these programs need to be
written or re-written by AMSAT volunteers!
W2GPS, May 5, 2002
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AO-E Receivers and Antennas
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VHF antenna is a very thin ¼ wave whip in the center of
the top surface of the spacecraft.
» Feeds the low insertion loss bandpass filter, then
» a GsAsFET Low Noise Amplifier with a noise figure <1 dB and
18 dB gain, then
» a second bandpass filter, and
» a four-way power divider that channels the incoming signal into
four VHF receivers.
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Four miniature VHF FM receivers
» <40 mW each and weigh less than 50 gm.
» Typical sensitivity is –122 dBm.
» IF bandwidth 15 kHz or 30 kHz, based on data rate
requirements.
W2GPS, May 5, 2002
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AO-E Transmitters and Antennas
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Two UHF FM transmitters that each have a PLLbased exciter and a Motorola high-power amplifier.
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Small size and low mass.
High efficiency.
On orbit adjustable output power from 1 to 12 watts.
Nominal operation is at 7.5 volts.
Analog or digital data rates up to 56 kbit/s and beyond are
possible.
» The overall gain of the UHF power amplifier is 39 dB.
» Up to 12 watts of RF output at >60% efficiency excluding the
2mW exciter.
» Both transmitters can be operated at the same time into a
single antenna system.
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UHF Turnstile Antenna is fed by hybrid antenna
phasing network to each of four output antenna ports
with less than 0.5 dB of insertion loss.
W2GPS, May 5, 2002
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AO-E Space for Optional Payloads
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Advanced Data
Communications for the
Amateur Radio Service
(ADCARS)
L-Band/S-Band
Communications System
GPS Receiver
Active Magnetic Attitude
Control
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W2GPS, May 5, 2002
Audio Recorder
Experiment
Low Frequency Receiver
APRS
PSK-31
Multi-band
Receiver/Antenna
High Efficiency Solar
Arrays
Robust Telemetry Link
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AMSAT OSCAR-E (AO-E) Summary
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Analog operation including FM voice.
Digital operation including high speed APRS.
Higher downlink power.
Multiple channels using two transmitters.
Can be configured for simultaneous voice and data.
Has a multi-band, multi-mode receiver.
Can be configured with geographically based personalities.
Has a true circular UHF antenna that maintains its circularity over a
wide range of squint angles.
Higher data rates on downlinks.
Autonomous, self-healing, high efficiency power management
system.
Store and forward with continuous monitoring and geographically
defined data forwarding.
W2GPS, May 5, 2002
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Advanced Data Communications for the
Amateur Radio Service (ADCARS)
Apply digital encoding techniques to improve
communication links and bandwidth utilization.
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Wide-band TDMA single frequency data link
for multiple simultaneous users and modes.
» voice, data, video, telemetry, etc.
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S-band downlink, due to bandwidth
requirements.
L-band uplink.
Optional signal regeneration.
Optional integration with on-board systems.
» File transfer » Data communication
» MPEG recordings
» Telemetry
W2GPS, May 5, 2002
Channel capacity:
S
C  B log2(1  )
where:
N
C = channel capacity, bits/sec
B = channel bandwidth, Hz
S = signal power, W
N = noise power, W
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Robust Telemetry Link
A Design Example
Demonstrate the value of using FEC and interleaving to
improve telemetry reception by ground stations.
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Encoding and Interleaving
» Reed-Soloman + Interleaver +
Convolutional Encoder, as proposed by
KA9Q for AO-40.
» Supports worst case operations.
» Provides link gain.
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Possible link designs
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AO-E Architecture Constraints
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All data goes to an NEC 72001 SCC.
Then to an FPGA shaping circuit.
Then to the varactor modulator.
Data rates from 600 to 64K baud.
Design Flexibility
» Full control over the SCC.
» 9600 baud FSK, as implemented in the
» Some control over shaping in FPGA.
Kenwood TM-D700A and TH-D7AG so
» Can adjust the amplitude and offset of
that APRS UI frames can be
signal to varactor.
interspersed with the telemetry.
 Implementation
» 56K bps GMSK for max throughput.
» Software in IHU.
» There is no possibility of 1200 bps AFSK
on this satellite.
» Hardware + Firmware (PIC?).
W2GPS, May 5, 2002
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Project Eagle
(Was Project JJ)
Demonstrate the value of using FEC and interleaving to
improve telemetry reception by ground stations.
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Launch Vehicle
» Has a big impact on
physical design.
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» Approx 50 kg, 50-60 cm.
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Orbit
Propulsion
» Probably needed to
raise perigee.
» May be needed for
reentry.
W2GPS, May 5, 2002
Spin Axis
» Jansson – point at user at
apogee.
» Johnson –perpendicular
to plane of orbit.
» GTO is lowest cost
vs. performance.
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Size and Weight
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Solar Panels and Power
Antennas
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