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2001 University of TokyoCUBESAT Project
University of TokyoCubeSat Project
CRITICAL DESIGN REVIEW
April, 6, 2001
Intelligent Space Systems Laboratory
University of Tokyo
2001 University of Tokyo CUBESAT Project
■Contents
•Project Overview
–CubeSat program, Organization, Management, Schedule
•Mission Overview
–Design Assumption, Mission Objective, Mission Profile, Success Level
•System Design
–Design Strategy & Concepts
•Subsystem Details
–Electronics, Power, Communication, Structure, Environment, Ground Segment
•Concerns
2001 University of TokyoCUBESAT Project
Project Overview
2001 University of Tokyo CUBESAT Project
■CubeSat Program
・ Proposed in University Space Systems Symposium. (Nov. 1998, Hawaii)
・ International educational program to improve students’ skill of space engineering and project management.
・ Quick and low cost development policy.
・ 10cm cubic satellite weighing less than 1kg.
2001 University of Tokyo CUBESAT Project
■Project Constraints
・ 10cm cubic shape, weight less than 1kg.
・ Installed in the carrier called “P-POD”, developed by CalPoly.
・ P-POD is to be installed in MPA (Multiple Payload Adopter), developed by One Stop Satellite Solutions Inc.
・ Launched by Russian rocket “Dnepr” from Baikonur in November, 2001.
・ Orbit 600-800km circular, 60 degree inclination
・ HAM band operation
2001 University of Tokyo CUBESAT Project
■CubeSat Developers
・ California Polytechnic State U ・ Dartmouth College・ Florida Space Institute・ Leland High School・ Montana State University・ Stanford University・ Stellar Innovations
・ Taylor University ・ Tokyo Institute of Technology・ University of Arizona・ University of Tokyo・ Wilcox High School
2001 University of Tokyo CUBESAT Project
■CubeSat Program Organization
ISC Kosmotras OSSS Inc. Stanford U
CalPoly
Astro Reserch Co.
Japan・ U of Tokyo・ Tokyo Inst. of Tech.
U.S.A.10 Facilities
Launcher Provider
Japan-side Agency
Carrier Provider
OS2 Mission Organizer
CubeSat Developers
U.S.A.Japan
Russia
2001 University of Tokyo CUBESAT Project
Dnepr LVLaunch weight 211 t Propellant amyl + heptyl Number of stages 3 LV diameter 3m LV length 34m Reliability 0.97Payload 400kg (800km)
1400kg (600km)(inclination 65deg)
MPAMass < 300kgIsogrid SpaceframeDeploys Payload SatellitesThree-axis Stabilization
P-PODDeployes 3 CubeSats
CubeSat
■Payload Configuration
2001 University of Tokyo CUBESAT Project
■UT’s Project Organization
Prof. Nakasuka
Program Director
Y.Tsuda
Project Manager
Y.Arikawa
Electronics
Y.TsudaN.MiyamuraS.IshikawaT.MurakamiE.HwanK.Kanairo
T.Ito
Communication
Y.KatoT.EishimaS.UkawaS.Ihikawa Y.Kuwata T.Yamamoto S.Ganryu
N.Sako
Power
T.EishimaY.ArikawaS.UkawaR.FunaseS.Hori
N.Miyamura
Structure
T.ItoS.Ogasawara
P.Seo
Environment
N.SakoK.KanairoK.Muramatsu
S.Ogasawara
Ground Seg.
Y.TsudaT.MurakamiY.OdaI.Ikeda
・ 21 active members・ General meeting every 1-2 week(s)・ Subsystem meeting every week
2001 University of Tokyo CUBESAT Project
■Development Milestone
XI-I・ Basic functional check
・ Technological demonstration for USSS conference
XI-II・ Bread board model
・ Validation of all technology to be used
XI-III・ Engineering model
・ Served to the integration & environmental testing
XI-IV,V・ Flight model & back up model
・ One for flight, the other for operation practice etc.
Communication test model, Mass model, CDR
Development code : XI [sai] (X-factor Investigator)
2001 University of TokyoCUBESAT Project
Mission Overview
2001 University of Tokyo CUBESAT Project
■“XI” Outlook
Antenna
Camera Hole
Flight Pin Hole
Solar cells are to be attached on whole surface
Antenna Latch Mechanism
photo: XI-II (BBM model)
2001 University of Tokyo CUBESAT Project
■Mission Description
■Mission Statement"To acquire the indispensable technology in developing super-
small satellite system"
■Mission・ Gathering the satellite’s health information via beacon signal.・ Command uplink & data downlink.・ Telemetry data broadcasting service.・ On-orbit verification of the commercial-off-the-shelves (COT
S) components.・ Imaging experiment as an extended mission. (TBD)・ Sending everyone’s message into space.
2001 University of Tokyo CUBESAT Project
■Success Level (1)
■Project’s Minimum Success--- Acquiring the important technology and knowledge through designing and fabricating the spacecraft. ・ Establishing overall work flow of the satellite development project. ・ Establishing a methodology of spacecraft design. ・ Raising the fabrication technique. ・ Conducting several kind of testing and feeding back its results to the design. ・ Keeping the project progressing smoothly so as to bring it to be the launchable condition.
■Mission Success--- Receiving signals from the spacecraft. ・ Surviving in the actual launch environment. ・ Successfully verifying the function of the communication system. ・ Gathering house keeping data.
2001 University of Tokyo CUBESAT Project
■Success Level (2)
■Full Success--- Succeeding in uplink & downlink. ・ Successfully commanding the spacecraft by uplink. ・ Getting downlink data as a reaction to the command uplink.
■Advanced Success--- Successfully verifying the function of the advanced mission components. ・ Verifying that sensors planned to be equipped as advanced mission components
should work normally.
2001 University of Tokyo CUBESAT Project
■Mission Profile (1)
・ Launched by Dnepr from Baikonur in Nov. 2001.
・ MPA is put in 600-800km circular orbit with 60 degree inclination.
・ MPA deploys some of its payloads & activates P-POD.
・ P-POD deploys CubeSats.
・ CubeSat starts operation after a certain elapsed time.
2001 University of Tokyo CUBESAT Project
■Mission Profile (2)
1. 2. 3.
■Post Ejection Stand-by
Main OBC is activated while the other components are off.
■Nominal Operation
Antenna is deployed. All components including beacon are activated except telemetry transmission system.
■Telemetry Transmission
This mode occurs as a reply to the uplink command from ground station.
2001 University of TokyoCUBESAT Project
System Design
2001 University of Tokyo CUBESAT Project
■Basic Specifications
●Structure 10cm cubic, 1kg, Aluminum A7075 body
●Main ProcessorOBC PIC16F877 4MHz ( Program memory 8k, RAM 368)Data Recorder EEPROM 32k + 224k
●Communication SystemDownlink 437.490MHz, FSK, AX.25, 1200bps, 600mWUplink 145.835MHz, FSK, AX.25, 1200bpsBeacon 436.8475MHz, CW, 100mW
●Power SystemBattery Manganese type lithium-ion battery, 8 parallelSolar Cells Single crystal silicon, 60 cellsBus Voltage 5V
●Attitude Control Passive stabilization using permanent magnet
●Sensors Voltage, Current, Temperature, Area sensor
StructurePower
Com1Main
Com2
Important Analog Sensors
Analog Sensors
Digital Sensors Antenna Latch
Battery
Solar Cell
DC-DC1
DC-DC3 OBC
ROM TX TNC
RX TNC
CW Gen
TX
RX
CWCharge Circuit
OBC
RX TNC
Analog SW
TX
uSW
Flight Pin
Flight Pin PWR5V
TLM
TLM
CMD
TLMACK
DC-DC2
OBC
PWR5V
2001 University of Tokyo CUBESAT Project
■Internal Function Design Strategy
Battery
Solar Cell
Camera Module
Temperature Sensors Communication Unit
Power Unit
Data Handling UnitMother Board
Electronics Subsystem
Power Subsystem
Communication Subsystem
Structure Subsystem
■Mother board intervenes inter-subsystem signal & power flow.
2001 University of TokyoCUBESAT Project
Structure Subsystem
2001 University of Tokyo CUBESAT Project
■Structure Subsystem
3. Antennae DeploymentMechanisma) Magnetic Plungerb) Folding Method
1. Body of CUBESATa) Assemblyb) Weight and Center Of Massc) Materiald) Size
4. Strength Analysisa) Behavior as Cantilever Beamb) Ceiling panel’s vibrationc) Load Estimationd) Countermeasure for vibration(Antennae)
2. Interfacea) Flight Pinb) External Input/Outputc) Connectord) Kill Switch
2001 University of Tokyo CUBESAT Project
■Body of CUBESAT
a) Assemblyb) Weight and Center Of Massc) Materiald) Size
Center Of Massx
y
z
2001 University of Tokyo CUBESAT Project
■Assembly of XI-II
■ First, Subsystem Boards are attached to Mother Board.
■ Then,that module is attached to 4 pillars.
■ Finally,Solar Cell panels covered CUBESAT’s surface.
Panels to put up solar array on
The mainstay of XI-II+x panel
+y panel
+z panel
2001 University of Tokyo CUBESAT Project
■Construction of subsystem board
■ Each subsystem board is attached to Mother Board.
■ Battery and I/F connectors are also attached to Mother Board.
Transceiver
Communication board
Main motherboard
Sub motherboard
Battery box
Power board
Electronic board
I/F board
2001 University of Tokyo CUBESAT Project
■Center Of mass
■ The difference of geometric center between center of mass
is 7.8mm (within 20mm)
■ Total mass is
990g (within 1kg)
Center Of Massx
y
z
2001 University of Tokyo CUBESAT Project
■Material
■ A7075 is the same material of P-POD which means that
thermal expansion is equal.
USE PRODUCTMain Structure A7075PCB Glass EpoxyBattery Li- ion Rechargeable batterySolar Cell Si- CellIC Plastic PackagedWiring Teflon coated
Bolt,Nut SteelAntenna Convex tape
2001 University of Tokyo CUBESAT Project
■Front view of XI-II
■ Solar cells mounted on EXTERNAL MOUNTING SURFACE do NOT exceed 6.5mm
■ Antennae are also mounted on EXTERNAL MOUNTING SURFACE.
2001 University of Tokyo CUBESAT Project
■Bottom view of XI-II
■ Antennae are mounted within 6.5mm.
■ 2 Kill Switches are mounted on this plane.
2001 University of Tokyo CUBESAT Project
■Interface
a) Flight Pinb) External Input/Outputc) Connectord) Kill Switch
2001 University of Tokyo CUBESAT Project
■Installation of CUBESAT
■ 3 CUBESATs can be installed in a P-POD carrier.
■ We can get some experimental data from I/F hole before launch.
2001 University of Tokyo CUBESAT Project
■Interface System
Plunger
Flight PinV up
V down
Antenna Deployment Order
Charge up
Charge down
GNDBattery VDCDC 5V for electronicsDCDC 5V for communicationDCDC 10V V operate 4VExternal TxExternal Rx
Subsystem
External InterfaceRJ-45
12345678
MicroSwitch Switch Unit
Switch Unit
Flight Pin 2
2001 University of Tokyo CUBESAT Project
■Mother Board
■ All Subsystem Boards are attached to Green connector.
2001 University of Tokyo CUBESAT Project
■Interface Board
■ All External I/F is allocated to Interface Board■ Interface Board has some module as follows.
• Kill Switch
• Before-Flight Pin
• External I/O Connector
RJ-45 Connector
Before-Flight Pin
Kill Switch
2001 University of Tokyo CUBESAT Project
■External Interface
■ We use RJ-45 connector.■ Even if CUBESAT is installed in the P-POD , we can get the data
witch the table shows.
No(Ext) Name Function
1 GND(1) Ground
2 BATT(2) Battery
3 E- DC(3)DCDC- Converter(for Erectricsubsystem) output
4 C- DC(4)DCDC- Converter(for Communicationsubsystem) output
5 Tx- DC(5)DCDC- Converter(for TelemetryTransmitter) output
6 EXT Tx(36) External serial Tx
7 EXT Rx(37) External serial Rx
8 VTO CMOS Image sensor NTSC signal
8,7,6,5,4,3,2,1
RJ-45 Connector
RJ-45 Plug
2001 University of Tokyo CUBESAT Project
■Kill Switch
■ We use 2 Kill Switches in parallel for redundancy.■ When one of 2 switches is ON , all system can get
power.
OFF ON
Kill Switch
2001 University of Tokyo CUBESAT Project
■Flight Pin
■ Switch1:Supplying power to the system.■ Switch2:OPEN/CLOSE battery charging circuit.
Sw
itch
1
Sw
itch
2
2001 University of Tokyo CUBESAT Project
■Antennae Deployment Mechanism
a) Magnetic Plungerb) Folding Method
2001 University of Tokyo CUBESAT Project
■Antenna Deployment System
■ Antenna is deployed using Electromagnetic Plunger
+V is impressed
The piece is capturedby the magnet Magnetic Power decreases
And the piece is released
Electromagnetic Plunger fa = 3.5 [N] min. fb = 0.8 [N]
fa
fb
2001 University of Tokyo CUBESAT Project
■Antenna Deployment System
Antenna Deployment Video
2001 University of Tokyo CUBESAT Project
■Strength Analysis
a) Behavior as Cantilever Beamb) Ceiling panel’s vibrationc) Load Estimationd) Countermeasure for vibration(Antennae)
2001 University of Tokyo CUBESAT Project
■Behavior as Cantilever Beam[1]
■ If CUBESAT experiences very strong vibration, it may behave as a cantilever beam.
■ In this case , the Harmonic
Frequency is around 20[kHz] (witch is enough high, comparing to the launch vehicle’s
frequency)
2001 University of Tokyo CUBESAT Project
■Ceiling panel’s vibration[1]
■ Harmonic Frequency is around 1 - 2 [kHz]
■ The Harmonic Frequency largely depends on the thickness of the panel.
■ The thicker the panel is designed , the higher the Harmonic Frequency becomes.
2001 University of Tokyo CUBESAT Project
■Ceiling panel’s vibration[2]
■ To avoid ceiling panel’s vibration we have to design it as possible as thick.
■ For this design , Total Mass is large problem
■ Eventually,we have to choose around
1.0-1.5mm
Thi ckness of panelvs Harmoni c f requency
0. 0
0. 5
1. 0
1. 5
2. 0
2. 5
3. 0
0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 3. 0 3. 5
Thi ckness of panel [mm]
Harm
onic
Freq
uenc
y(n=
m=1)
[kHz
]
920
940
960
980
1000
1020
1040
1060
1080
1100
Tota
l Ma
ss[g
]
Harmoni cFrequencyTotal Mass
2001 University of Tokyo CUBESAT Project
■Load Estimation
■ The 3rd CubeSat experiences maximum load while 2nd stage flight• The maximum stress is
0.011kgf/mm2
(enough for Aluminum use)
P-POD
Maximum Stress
7.7g
(max
)
2001 University of Tokyo CUBESAT Project
■Countermeasure for vibration(Antennae)
■ To complete any mission , fastening and deploying antennae is very important.
■ It is difficult to simulate the behavior of the antenna , so we conduct some experiments to confirm the feasibility of this design.
■ Fixing antennae with several points.
2001 University of TokyoCUBESAT Project
Electronics Subsystem
2001 University of Tokyo CUBESAT Project
■Function of Electronics
• Health monitoring • Command & data-handling• Resetting DCDC• Antenna deployment • Controlling area sensors
Our Works
• Satellite system management• Capturing images with area sensors
Our Goals
2001 University of Tokyo CUBESAT Project
■Block Diagram
OBC
OBC Program&
ROM Read/WritePins
SDA Line
SCL LineROM0ROM0ROM0ROM0ROM0ROM0ROM0ROM0
Thermometer0 to 7
MPX
MPX_SEL0 ~2
Battery VoltageCharge Current
Reset Signal (Power Sub Sys.)
Battery Charger IC Reset Signal
SEL Detect
C-DCDC 5VTo CommSub Sys.
E-DCDC 5V
CW-CtoE
CW-TNC
Tx-TNCTx-CtoE
CW-EtoC
Tx-EtoC
Rx-EtoC
Rx-CtoE
Rx-TNC
(Structure Mother Board)
Solar Cell Current 1 to 6MPX
2001 University of Tokyo CUBESAT Project
■Command & Data-Handling
Ground Station in UT
OBC
Tx-TNC CW-TNC
ANTD /CRNT /DCDCMTQC /POWR/ROMDSOLA /TEMP /VOLT
Uplink Command
CRNT /ROND /SOLATEMP /VOLT
Fixed length = 17 bytes
2001 University of Tokyo CUBESAT Project
■Command & Data-Handling(2)
●Antenna deployment ●Requesting current data (Total , Solar Array , C-DCDC , E-DCDC) ●Resetting C-DCDC ●Resetting charging circuit ●Requesting EEPROM data ●Requesting temperature data (Battery , Solar Array , FM-Transmit) ●Requesting voltage data (Battery , Solar Array)
2001 University of Tokyo CUBESAT Project
■Command & Data-Handling(3)
●Current ----- 9 bytes (Total , Solar Array , C-DCDC , E-DCDC)●EEPROM Data ----- Undecided●Current & Temperature of Solar Array ----- 12 bytes●Temperature ----- 8 bytes (Battery , Solar Array , FM-Transmit)●Voltage ----- 2bytes (Battery , Solar Array)
2001 University of Tokyo CUBESAT Project
■Command & Data-Handling(4)
Time
Status
Picture
Current
Voltage
Additional Data
3 bytes
1 bytes
1 bytes
2 bytes
9 bytes
1 bytes
2001 University of Tokyo CUBESAT Project
■Components of Electronics
ROM Module
ROM READ/WRITE Pin
For Thermometer
For Camera
JumperPin For ROM
XI-II model
2001 University of Tokyo CUBESAT Project
■Components of Electronics-(2)
OPAmp Module
Thermometer Module
Program Pin
XI-II model
2001 University of Tokyo CUBESAT Project
■Components of Electronics-(3)
ROM (24LC256)
PIC 16F877
• Clock :4MHz• Memory :8kword• RAM :368bytes• EEPROM :256bytes• Operative Voltage:2.0~5.5V
• I2C serial EEPROM• Memory :256Kbit(32Kbyte)• Max erase/write cycles:100,000• Max write-cycle time :5ms• Max clock frequency :400kHz
2001 University of Tokyo CUBESAT Project
■Thermal Monitoring
Thermal Sensor ( Thermal Sensor ( LM335Z )LM335Z ) ・ Power consumption:5mW ・ Measuring range :-40~100℃ ・ Characteristic :10mV/℃ ・ Precision :±1℃
MonitoringMonitoring ・ Temperature of Battery, Solar Panel(6) and Transceiver. ・ AD converting a data & sending it to comm subsystem.
Thermal Sensor Calibrationy = 99.218x - 270.29
-505
10152025303540
2.7 2.8 2.9 3 3.1Voltage[V]
Tem
pera
ture
[℃]
● data―linearized
2001 University of Tokyo CUBESAT Project
■Function of Reset-(1)
E-DC OBC
Rx-TNC
V in
Pch FET
Pch FET
ac
P.U.
P.U.
P.U.
P.D.
P.D.
P.U. = Pull UpP.D. = Pull Down
C-DC
SEL Detect
Nch FET
Nch FET
SEL Detect
CW-GEN
Tx-TNCPch FET
bd
e
A
A
ba c d
Tx-DCe
2001 University of Tokyo CUBESAT Project
■Function of Reset-(2)
CPU
If a=1&b=0
DCDCVin
Two wire AND reset system using FET
• PchMOSFET• NOT gate
Switching CircuitSwitching Circuit
For SEL tolerance, reset function is needed.Reset system requires high reliability so as not to shut off continuously even in CPU malfunction case.
2001 University of TokyoCUBESAT Project
Communication Subsystem
2001 University of Tokyo CUBESAT Project
■Communication System Diagram
OBCOBC
Tx TNCPIC16C622
Rx TNCPIC16C711
ModulatorMX614
DemodulatorMX614
Telemetry data Beacon data Up-link command
AD Convert
AX25 Coded datawith Parity
FSK modulated command
AX25 Coded command
Morse Coded dataPTT Control
Half wave lengthdipole antenna
Half wave lengthmonopole antenna
Nishi RF Lab.Custom made
FM transmitter
Nishi RF Lab.Custom made
CW transmitter
Nishi RF Lab.Custom madeFM receiver
SensorsSensors
FSK modulated data
Antenna SW
switching
NegotiationMorse encoder
PIC16C716
PLLControl
PLLControl
PLLControl
2001 University of TokyoCUBESAT Project
Telemetry Transmission System
2001 University of Tokyo CUBESAT Project
■Tx TNC (AX.25 encoder)
■Tx TNC : Micro controller PIC16C622-program memory(EPROM) : 2 kbyte-data memory(RAM) : 128 byte-clock : 4 MHz-I/O port : 13 (4 AD Converters)-power consumption : 2.0 mA @ 5V
■Tx TNC receives telemetry data from OBC ■Puts Parity byte for error detection■Encodes the telemetry data with AX.25 protocol■Sends encoded data to FSK modulator
PIC16C622
AX.25 Protocol■This protocol is mainly used for data transmission by HAM■Every Amateur Radio Station all around the world can decode our telemetry data!!!
Flag Destination Source Control PID parity data parity data FCS Flag
AX.25 frame structure(with Parity)
2001 University of Tokyo CUBESAT Project
■Tx TNC Program
Receive data from OBCReceive data from OBC
Packetize into AX25 formatPacketize into AX25 format
data from OBC ?data from OBC ?
Yes
No
Send packet to FSK modulatorSend packet to FSK modulator
Start & InitializationStart & Initialization
2001 University of Tokyo CUBESAT Project
■FM Transmitter
FM transmitter System Diagram
■FM Transmitter is used to transmit telemetry data■Nishi RF Laboratory custom made transmitter
-frequency:-band width:-RF output power:-input power:-operative temp.:-volume: (including CW transmitter)
437.490MHz20kHz1Wunder 6W-30℃ ~ +60℃90×60×10cm FM transmitter
2001 University of TokyoCUBESAT Project
Beacon Transmission System
2001 University of Tokyo CUBESAT Project
■CW Generator (Morse encoder)
■Morse encoder : Micro controller PIC16C716-program memory(EPROM) : 2 kbyte-data memory(RAM) : 128 byte-clock : 4 MHz-4 AD Converters (8bit)-power consumption : 2.0 mA @ 5V
■CW generator receives beacon data from OBC■Monitors sensor data independently from OBC (Countermeasure of OBC’s hang up)■Generates Morse code ■Controls the KEY of CW transmitter■Data rate : human decodable speed
Beacon data format"UT1" "UT4"
"UT2" time1 time2 time3 "UT5"tmp.
battery1tmp.
battery2tmp.
battery3tmp.
battery4tmp.
battery5tmp.
battery6
"UT3" Status Camera status battery V "UT6" tmp. Panel1
tmp. Panel2
tmp. Panel3
tmp. Panel4
tmp. Panel5
tmp. Panel6
"www.space.t.u-tokyo.ac.jp" total I tmp. battery tmp. Panel
PIC16C716
2001 University of Tokyo CUBESAT Project
Data Sampling
■CW Generator Program
Start & InitializationStart & Initialization
Data sensing (AD Convert)Data sensing (AD Convert)Receive data from OBCReceive data from OBC
UT1 www.space.t.u-tokyo.ac.jpUT1 www.space.t.u-tokyo.ac.jp
Yes
No
No
YesOBC ready
to send data?
OBC ready to send data?
Counter < 10secCounter < 10sec
UT2 AA BB CC UT2 AA BB CC
UT3 DD EE FF UT3 DD EE FF
UT4 GG HH II UT4 GG HH II
UT5 JK LM NO UT5 JK LM NO
UT6 PQ RS TUUT6 PQ RS TU
Data Sending
2001 University of TokyoCUBESAT Project
Command Receiving System
2001 University of Tokyo CUBESAT Project
■Rx TNC : Micro controller PIC16C711-program memory(EPROM) : 1 kbyte-data memory(RAM) : 64 byte-clock : 4 MHz-4 AD Converters (8bit)-power consumption : 2.0 mA @ 5V
■Rx TNC receives AX.25 encoded command from FSK demodulator■Decodes it and sends command to OBC
OBC Reset System■If the command is “Reset Command”, resets OBC■Monitors OBC’s current and resets OBC in case of SEL (Countermeasure of OBC’s SEL)
■Rx TNC (AX.25 decoder)
PIC16C711
2001 University of Tokyo CUBESAT Project
■Rx TNC Program
Interruption RoutineStart & InitializationStart & Initialization
set ‘Receiving’ flagset ‘Receiving’ flag
Reset OBCReset OBC
Command = “rset”or flag_rst = 1 ?
Command = “rset”or flag_rst = 1 ?
clear ‘Receiving’ flagclear ‘Receiving’ flag
Receive Uplink commandReceive Uplink command
Wait 10 [ms]Wait 10 [ms]
Send serial data to OBCSend serial data to OBC
Yes
OBC ready to receive?OBC ready to receive?
flag_rst = 0flag_rst = 0
No
No
Main Routine
Yes
‘Total I’ > Threshold ?‘Total I’ > Threshold ?
flag_rst = 1flag_rst = 1
A/D convert ‘Total I’A/D convert ‘Total I’
Yes
2001 University of Tokyo CUBESAT Project
■FM Receiver
■FM Receiver is used to receive up-link command■Nishi RF Laboratory custom made receiver
-frequency:-input power:-receive sensitivity:-receive output:-operative temp.:-volume:
145.835MHzunder 100mWunder -16dBμ16dBV typ.-30℃ ~ +60℃50×60×10cm
FM receiver
2001 University of Tokyo CUBESAT Project
■Antenna Configuration
Antenna for Receiver144MHz Half wavelength monopole antenna
Antenna for Transmitters430MHz band Half wavelength dipole antenna
2001 University of Tokyo CUBESAT Project
■Antenna Pattern (Transmitter)
Antenna Absolute GainTransmitters' Half wavelength dipole Antenna
(dBm)
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
Gt
Gt,req
The gain which we can decode the data in our ground station
2001 University of Tokyo CUBESAT Project
■Antenna Pattern (Receiver)
Antenna GainReceiver's Half wavelength monopole antenna
(dBm)
- 55.00
- 50.00
- 45.00
- 40.00
- 35.00
- 30.00
- 25.00
- 20.00
2001 University of Tokyo CUBESAT Project
■Link Budget (Telemetry Tx)
Symbol Unit Telemetry RemarkFrequency f MHz 437.400Transmit P ow e rP W 0.600 ParameterTransmit P ow e rP dBW -2.218Transmitter Line Loss Ll dB -3.000 Usually -1dB -3dB~Transmit Antenna Half-Power Beamwidthθ t deg 110.000 Ideal dipo l ePeak Transmit Antenna Gain Gpt dB 2.148 Ideal dipo l eTransmit Antenna Pointing Offset et deg 90.000 UncontrolledTransmit Antenna Pointing Loss Lpt dB -8.033Transmit Antenna Gain Gt dB -5.885Equiv. Isotropic Radiated Power EIRP dBW -11.103Propagation Path Length S km 1439.940 50kbyte/1passSpace Loss Ls dB -148.434Propagation & Polarization Loss La dB -0.470 Polarization (-0.3dB)Peak Receive Antenna Gain Grp dB 12.500 GS 435HS20Receive Antenna Half-Power Beamwidthθ r deg 29.000 GS 435HS20Receive Antenna Pointing Error er deg 15.000 AssumptionReceive Antenna Pointing Loss Lpr dB -3.210Receive Antenna Gain Gr dB 9.290System Noise Temperature Ts dBK 25.700Data Rate R bps 1200.000 MX614Eb/ N 0 Eb/ N 0 dB 21.390Bit Er ro r Ra t eBER 0.000Required Eb/N0 Req Eb/N0dB-Hz 13.000 FSK, BER=10-5
Implementation Loss dB -5.000Margine dB 3.390
Link BudgetTelemetry (TDMA)
UT’sGround Station
CUBESATComm. System
2001 University of Tokyo CUBESAT Project
■Link Budget (Command Rx)
Symbol Unit Uplink RemarkFrequency f MHz 145.835Transmit P ow e rP W 20.000 ParameterTransmit P ow e rP dBW 13.010Transmitter Line Loss Ll dB -3.000 Usually -1dB -3d B ~Transmit Antenna Half-Power Beamwidthθ t deg 33.000 GS 144HS12Peak Transmit Antenna Gain Gpt dB 10.000 GS 144HS12Transmit Antenna Pointing O ffs e tet deg 15.000 AssumptionTransmit Antenna Pointing Loss Lpt dB -2.479Transmit Antenna Gain Gt dB 7.521Equiv. Isotropic Radiated Power EIRP dBW 17.531Propagation Path Length S km 1439.940Space Loss Ls dB -138.894Propagation & Polarization Loss La dB -0.470 Polarization (-0.3dB)Peak Receive A nte nn a Ga i nGrp dB -2.521 MonopoleReceive Antenna Half-Power Beamwidthθ r deg 100.000 MonopoleReceive Antenna Pointing Error er deg 90.000 UncontrolledReceive Antenna Pointing Loss Lpr dB -9.720Receive Antenna Gain Gr dB -12.241System Noise Temperature Ts dBK 31.100Data Rate R bps 1200.000Eb/ N 0 Eb/ N 0 dB 32.634Bit Er ro r Ra t eBER 0.000Required Eb/N0 Req Eb/N0dB-Hz 13.000 FSK, BER=10-5
Implemention Loss dB -5.000Margine dB 14.634
Link BudgetUplink Command
CUBESATComm. System
UT’sGround Station
2001 University of TokyoCUBESAT Project
Power Subsystem
2001 University of Tokyo CUBESAT Project
■Power Subsystem
AAAAAAA
ChargeCircuit
Batteries
A
SwitchingRegulator
Electronics Subsystem
A
SwitchingRegulator
Communication Subsytem
DCDCConverter
Tx
TNC OBC OBC
2001 University of Tokyo CUBESAT Project
■Power Subsystem(CONT’D)
■ Supply a continuous source of electrical power to loads.• Power source is solar panels.• Batteries are used for storage• Regulated DC power and unregulated power is
supplied for loads.• Power consumption is monitored for SEL.
2001 University of Tokyo CUBESAT Project
■Power Regulation & Control
■ Bus voltage: main 5[V]■ Regulated to 5V using
switching regulators and DCDC converter
■ Elect. subsystem power line & Comm. subsystem power lines are independent so that they monitor each other and shutdown in case of SEL
2001 University of Tokyo CUBESAT Project
■Source
■ Power is supplied by body mounted solar cells.
■ Cells are arranged on all 6 CubeSat surfaces.
■ Average power 1228 [mW] (typ @ 80 )℃
2001 University of Tokyo CUBESAT Project
■Solar Panel
■Cell type : Si Crystal (SHARP)■Efficiency : 16%■10 cells in series / panel■Cell size:
+X :28.25x13.8mm-X,+Y,-Y:47.75x13.8mm+Z,-Z :47.75x15.8mm
Bass bar
Photo:3 cells in series
2001 University of Tokyo CUBESAT Project
■Solar Array Layout (+X panel)
+X panel:
4.5V x 172mA = 774mW(typ. @ 25 )℃
4.5V x 162mA = 727mW(typ. @ 80 )℃
2001 University of Tokyo CUBESAT Project
■Solar Array Layout (-X,+Y,-Y panel)
-X,+Y,-Y panels:
4.5V x 297mA = 1336mW(typ. @ 25 )℃
4.5V x 279mA = 1256mW(typ. @ 80 )℃
2001 University of Tokyo CUBESAT Project
■Solar Array Layout (+Z,-Z panel)
+Z,-Z panels:
4.5V x 340mA = 1530mW(typ. @ 25 )℃
4.5V x 319mA = 1438mW(typ. @ 80 )℃
2001 University of Tokyo CUBESAT Project
■Energy Storage
■ Batteries will be used during eclipse and downlink
■ Liion secondary batteries are selected.
■ 8 batteries are set in parallel.■ DOD is 3%■ Batteries only lifetime is 38 hr
s
2001 University of Tokyo CUBESAT Project
■Liion battery
Cathode Material Lithium Manganate
Anode Material Carbon
Operating Voltage 3.8[V]
Discharge Capacity 780 [mAhr]
Single Cell Spec.
2001 University of Tokyo CUBESAT Project
■Battery Charger
■ 3 candidates for Battery Charge Circuit
MAX1679
•Small package (8 pins), small power dissipation•Voltage&Temperature protection•Pre-charge, Timeout
•Need constant reset before IC’s timeout
MM1333
•Small package (8 pins), small power dissipation•Const. Voltage & Current Charge Mode
•No pre-charge func or temperature protection
MM1485
•Small power dissipation•Const. Voltage & Current Charge Mode•Pre-charge Temperature protection
•Large package (16 pins) and may be difficult to assembly
2001 University of Tokyo CUBESAT Project
■Energy Consumption
OBC 20 All timessensors 20 All timesTx TNC 20 During downlinkTx 6000 During downlinkCW 300/125 All times (ON / OFF)CW TNC 20 All timesRx 125 All timesRx TNC 20 All timesCamera 150 SometimesMagnetic Plg. 800 Antennae deployment
Components Power[mW] Frequency in use
2001 University of Tokyo CUBESAT Project
■Power Balance
■ Points• Beacon can be sent by solar panels direct drive• Source and consumption must be balanced
■ Solar cell average output 1228[mW] > Consumption at beacon use 900[mW]
■ Maximum average supply power: 669[mW] > Average consumption 616[mW]
OK
OK
2001 University of Tokyo CUBESAT Project
■Attitude Control
■ Objectives• To make CubeSat tumble in order to smooth thermal
input• Point antennae to the ground station
■ Methods• Use a permanent magnet and a libration damper
2001 University of Tokyo CUBESAT Project
■Control Mechanism
■ Torque will be generated to align earth magnetic direction and CubeSat’s dipole moment.
■ Libration is damped by energy dissipater.
Magnetic Field
Dipole Moment
Antennae
Ground Station
2001 University of Tokyo CUBESAT Project
■Torquer Sizing
Required Torque1.0E-6 [Nm]
Required Magnetic Dipole Moment 0.046 [Am^2]
AirDrag 2.26E-10
Solar Pressure 1.38E-9
Gravity Gradient 1.25E-8
To follow the change of magnetic field
Disturbance Torque[Nm]
1.0E-6At 800km magnetic field
2001 University of Tokyo CUBESAT Project
■Permanent Magnet
Material Alnico-5
Magnetic Dipole Moment 0.05 [Am^2]
Size φ4*25 [mm]
Weight 2 [g]
Residual Magnetic Flux Density 1300 [mT]
2001 University of Tokyo CUBESAT Project
■Libration Damper
■ Libration damper dissipates energy to stable attitude change.• Dissipation caused by hysteresis loss and eddy curre
nt loss• High permeability iron is used for the damper• 3days are expected (8 days for worst case) to damp o
scillation
2001 University of TokyoCUBESAT Project
Environment Subsystem
2001 University of Tokyo CUBESAT Project
■Environmental Tests (outline)
Tried and Tested
Future Works
■Heavy ion testing(PIC16F877 F84 C622 C774)
■Heavy ion testing(PIC16F877 C774 C622)
■Li -ion battery testing (in a vacuum) ■C-MOS Camera testing
(in a vacuum)
■ Thermostat EM-Plunger , Li -ion battery , C-MOS camera,Solar Panels
■ SEL testing DCDCs,OP-AMPs,Tx,Rx etc
■ Vibration testing Solar Panels , EM-Plunger,EM
■ Thermal Vacuum Chamber XI-II α , EM , FM1 , FM2
2001 University of Tokyo CUBESAT Project
■Analysis (outline)
■ thermal analysis We construct a model of heat transfer by means of the node point method using C-programming. We will complete building 50nodes model and fixing the value of every parameter from XI-IIα testing.
■ SEE analysis We calculated SEE rate using the CRÈME software and provided reset functions to XI-IIα.
( http://crsp3.nrl.navy.mil/creme96/ )
2001 University of Tokyo CUBESAT Project
■Tried and Tested
■Heavy ion testing ( at NASDA)2000.09.12 source ; Calfornium (Cf252)
Device Numberof SEU
Numberof SEL
Irradiationtime[sec]
Fluence[/cm 2̂]
SEE Cross Section[cm 2̂/bit]
F877 102 0 2502 332353 7.49272E-08
F84 101 3 1040 137956 3.57477E-07
C622 101 0 2599 344759 1.43046E-07
C774 101 0 2563 205669 1.19892E-07
(for quick look)
2001 University of Tokyo CUBESAT Project
■Tried and Tested
■Heavy ion testing ( at JAERI Takasaki)2000.10.09 source ; 20Ne4+, 40Ar8+, 84Kr17+
Device SEU(Ne)LET=6.01
SEU(Ar) LET=15.1
SEU(Kr) LET=38.3
F877 1.6468E-07 2.1559E-08 ----
C622 8.4045E-10 9.6120E-09 -----
C774 1.8376E-08 2.4405E-08 4.1931E-08
■Using CREME96 Results,We decided to use PIC16F877.
Device SEUs/device/dayF877 2.3514E-05C622 1.26733E-06C774 2.550029E-07
(height 600km,incrination=60°)
cf. LET[MeV/(mg/cm^2)],SEU[cm^2/bit]
2001 University of Tokyo CUBESAT Project
■Tried and Tested
■ Vacuum chamber testing- Li ion battery test (2001.01.21 - 23 at UT-Arakawa Lab.) No deterioration observed in 10^-5 Torr evacuated chamber.
2001 University of Tokyo CUBESAT Project
■Analysis
Quick look
Height=600kmincrination =60°6 nodes (CUBE planes) mass density = Al densityspecific heat=920*9[J kg^-1K-1]conductivity=240[W m^-1K^-1]ε=0.825α=0.805
Temperature of 6- nodes
- 8- 6- 4- 202468
10
0 20000 40000 60000 80000 100000
time[sec]
Temp
erat
ure[
degr
ee C
]
T1T2T3T4T5T6
2001 University of Tokyo CUBESAT Project
■Future Works
We have a plan to execute EM-Plunger and XI-II α test with thermal vacuum chamber. (2001.04.10. - at ISAS Ohnishi Lab.)
CW CW
Rx-TNCRx-TNC
Tx-TNCTx-TNC
OBCOBC
Battery
Vin(5V)
GND
PIC 5VMpx.B
A/D
Serial
SW
9-wires
Thermocouple sensor
flanged1flanged2(Dsub50)
BNC→ ONS
flanged2(Dsub50)
flanged2(Dsub50) Temperature sensor
Wires× 3GND
2001 University of Tokyo CUBESAT Project
■Future Works
Battery ON
OBC status(Serial)with checking telemetry
Communication system status
CW,Rx-TNC,Tx-TNC
Long timerunning
RunningOBC only
E5V C5V 10V Vop
RunningThermometerfor checking
yes
yes
yes no
no
Executing partial test.
2001 University of Tokyo CUBESAT Project
■Future Works
CW Rx Tx
Rx and Txcommunicate 300times per 5 minutesand suspend for25 minutes .
CW speak at all times.
...
...
...
...
2001 University of Tokyo CUBESAT Project
■Outgas Examination
We choose following products from out-gas point of view.
USE PRODUCTWiring Fluorocarbon wires (Hitachi Cable Ltd.)RTV LTV rubber KE1204(AL or BL)Rubber Si rubber KE9610/C-8BBonding Agent SYLGARD184 ; FSXA-2869
※However, they are not fixed yet.
USE TML CVCM WVRWiring <0.1 <0.01RTV 0.597 0.117 0.007Rubber 0.846 0.052 0.736Bonding Agent 1.740 0.660 0.040
2001 University of Tokyo CUBESAT Project
■Work Room
Work Room Environment
We will construct isolated work space to manufacture EM,FM1,FM2.(aiming at 1000-level clean room)
※Air conditionerHEPA Unit(SS-MAC) YAMATO science co.
2001 University of TokyoCUBESAT Project
Ground Segment
2001 University of Tokyo CUBESAT Project
■When can we contact?(1)
Pass time for 1 week
0
100
200300
400
500
600
700800
900
1000
05.
212
.427
.134
.349
.056
.161
.376
.197
.897
.810
6.7
121.
313
0.1
144.
715
1.7
166.
3
Simulation passage time[hr]
Pass
tim
e[s
ec]
2001 University of Tokyo CUBESAT Project
■When can we contact?(2)
最大迎角
0
10
20
30
40
50
60
70
80
90
1 3 5 7 9 1113 15171921 232527 29313335 373941 43454749
Max
imum
ele
vati
on a
ngle
(de
g)
Pass #
2001 University of Tokyo CUBESAT Project
■When can we contact?(3)
•There are 49 passes. which means we can contact with our CubeSat 6 or 7 times per day.•In those passes, 22 passes have an elevation over 20[deg].•The longest pass time is about 900[sec].•We have 1 or 2 chances to contact for 900[sec] everyday.
2001 University of Tokyo CUBESAT Project
■Necessary Time for Communication
CW Beacon Downlink•CW Beacon is consist of 73 words.•If duty ratio is 0.3, it takes about 240[sec] to send 73 words. (60 words per minute )
FM Packet Telemetory downlink•Packet length is about 80 bytes.•Baud rate is 1200 [bps] , so it takes 0.54[sec] to receive a packet.
2001 University of Tokyo CUBESAT Project
■Operation Plan
CW Beacon Uplink Command
If we can receive the CW Beacon,we send Uplink Command once or twice a day.
FM Packet 1200bps
2001 University of Tokyo CUBESAT Project
■How to handle Downlink Data
We expect it may be difficult for us to receive and decode downlink data perfectly,so we prepare backup system to get something of traces of downlink data.
•Recording CW Beacon & Telemetry Packet to Mini Disk.•Original TNC skipping CRC (check sum).
2001 University of Tokyo CUBESAT Project
■Ground Station Equipment(1)
144MHz/430MHz Antenna Transceiver, TNC, etc.
2001 University of Tokyo CUBESAT Project
■Ground Station Equipment(2)
•144MHz/430MHz cross Yagi antenna [WHS32N, MASPRO]•430MHz cross Yagi antenna (TBD)
•Antenna rotator & controller for azimuth [750FX, EMOTATOR]•Antenna rotator & controller for elevation [EV800, EMOTATOR]
•VHF/UHF multi band all mode transceiver [IC-970J, ICOM]•VHF/UHF multi band all mode transceiver (Equipped for 9600bps packets) [IC-910D, ICOM]
2001 University of Tokyo CUBESAT Project
■Ground Station Equipment(3)
•TNC [TNC505,TASCO]•TNC (With function to co-decode CW signal) [TNC555, TASCO]•TNC (Skipping CRC) [handmade]
•Signal converter [I/F between PC and rotators]•Level converter [CT17, ICOM (I/F between PC and Tranceivers]
•PC (OS:Window98)
•MDLP mode MD recorder (TBD) [MDS-S50, SONY]×2
2001 University of Tokyo CUBESAT Project
■Ground Station Configuration
IC-970J
IC-910D
TNC-505
TNC
TNC-555
PC(Windows98)MD recorder
MD recorder
Telemetory
Command
CW beacon
144MHz uplink
430MHz Telemetory downlink
430MHz CW downlink
EV-800
750FXSignal
converterCT17
Frequency, Azimuth, Elevation
http://www.space.t.u-tokyo.ac.jp/cubesat
2001 University of Tokyo CUBESAT Project
■Message Mission
■ Message from all over the world will be microfilmed and packed in CubeSat
■ Themes are • Dreams for space• CubeSat mission proposal etc.
■ Messages are accepted by postal cards.
■ Details are uploaded to WebPages
2001 University of Tokyo CUBESAT Project
■Program Timeline
CDR(3/19)*postponed
TCDR FM DeadlineMass Model Shipment
Long Range Comm. Experiment
74 5 63 8 9 10 11
EM Deadline
FM Shipment (8/15) Launch
red char. : contract matter
2001 University of Tokyo CUBESAT Project
■Concerns (Electronics)
■ We made a reset system for countermeasure against SEL, but still do not decide the SEL threshold current. How do we decide it and how much should we have a margin for it?
■ For countermeasure against SEU, we will set only Watch Dog Timer. Is it enough? How can we detect SEU?
2001 University of Tokyo CUBESAT Project
■Concerns (Communication)
■ When and by whom will our CubeSat’s call sign be distributed?
■ Only one frequency band is allocated for up-link command. If some developers uses the same protocol (ex. AX.25), ho
w each Cubesat distinguishes its GS’s command from other GS’s command? Are there any regulations?■ Does our Cubesat require an impedance matching circuit between transceiver and antenna? ■ Is it necessary to conduct a radiation environment test to FS
K modulator-demodulator?■ Must our Cubesat equip space rated coaxial cable? Now, we
are planning to use normal one (1.5D2V).
2001 University of Tokyo CUBESAT Project
■Concerns (Environment)
■ the thermal vacuum testing regulation for Flight Model
■ TML,CVCM limits
■ the Vibration testing on Flight Model.
2001 University of Tokyo CUBESAT Project
■Concerns (Power)
■ Is the use of a permanent magnet permitted?
■ When can we charge batteries last?
2001 University of Tokyo CUBESAT Project
■Concerns (Ground)
■ How can we get the orbital information of our CubeSat?
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