2001 University of Tokyo
CUBESAT Project
University of Tokyo
CubeSat 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 Tokyo
CUBESAT 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
Russia
Launcher Provider
ISC Kosmotras
OS2 Mission Organizer
OSSS Inc.
Stanford U
Carrier Provider
CalPoly
U.S.A.
Japan
Japan-side Agency
Astro Reserch Co.
CubeSat Developers
U.S.A.
10 Facilities
Japan
・U of Tokyo
・Tokyo Inst. of Tech.
2001 University of Tokyo CUBESAT Project
■Payload Configuration
MPA
Dnepr LV
Launch weight
211 t
Propellant
amyl + heptyl
Number of stages 3
LV diameter
3m
LV length34m
Reliability
0.97
Payload 400kg (800km)
1400kg (600km)
(inclination 65deg)
Mass
< 300kg
Isogrid Spaceframe
Deploys Payload Satellites
Three-axis Stabilization
P-POD
Deployes 3 CubeSats
CubeSat
2001 University of Tokyo CUBESAT Project
■UT’s Project Organization
Program Director
・21 active members
・General meeting every 1-2 week(s)
・Subsystem meeting every week
Prof. Nakasuka
Project Manager
Y.Tsuda
Electronics
Communication
Power
Structure
Environment
Ground Seg.
Y.Arikawa
T.Ito
N.Sako
N.Miyamura
P.Seo
S.Ogasawara
Y.Tsuda
N.Miyamura
S.Ishikawa
T.Murakami
E.Hwan
K.Kanairo
Y.Kato
T.Eishima
S.Ukawa
S.Ihikawa
Y.Kuwata
T.Yamamoto
S.Ganryu
T.Eishima
Y.Arikawa
S.Ukawa
R.Funase
S.Hori
T.Ito
S.Ogasawara
N.Sako
K.Kanairo
K.Muramatsu
Y.Tsuda
T.Murakami
Y.Oda
I.Ikeda
2001 University of Tokyo CUBESAT Project
■Development Milestone
Development code : XI [sai] (X-factor Investigator)
・Basic functional check
XI-I
・Technological demonstration for USSS conference
・Bread board model
XI-II
・Validation of all technology to be used
Communication test model, Mass model, CDR
・Engineering model
XI-III
・Served to the integration & environmental testing
・Flight model & back up model
XI-IV,V
・One for flight, the other for operation practice etc.
2001 University of Tokyo
CUBESAT Project
Mission Overview
2001 University of Tokyo CUBESAT Project
■“XI” Outlook
Antenna Latch
Mechanism
Solar cells are to
be attached on
whole surface
Antenna
Flight Pin Hole
Camera Hole
photo: XI-II (BBM model)
2001 University of Tokyo CUBESAT Project
■Mission Description
■Mission Statement
"To acquire the indispensable technology in developing supersmall 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 (COTS)
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
■Nominal Operation
■Telemetry Transmission
Main OBC is activated
while the other
components are off.
Antenna is deployed. All
components including beacon
are activated except telemetry
transmission system.
This mode occurs as a reply
to the uplink command from
ground station.
2001 University of Tokyo
CUBESAT Project
System Design
2001 University of Tokyo CUBESAT Project
■Basic Specifications
●Structure
10cm cubic, 1kg, Aluminum A7075 body
●Main Processor
OBC PIC16F877 4MHz（Program memory 8k, RAM 368)
Data Recorder
EEPROM 32k + 224k
●Communication System
Downlink
Uplink
Beacon
437.490MHz, FSK, AX.25, 1200bps, 600mW
145.835MHz, FSK, AX.25, 1200bps
436.8475MHz, CW, 100mW
●Power System
Battery
Solar Cells
Bus Voltage
Manganese type lithium-ion battery, 8 parallel
Single crystal silicon, 60 cells
5V
●Attitude Control
Passive stabilization using permanent magnet
●Sensors
Voltage, Current, Temperature, Area sensor
Structure
Power
PWR5V
OBC
Main
Com1
DC-DC1
TX
ROM
RX TNC
TX TNC
TX
Analog SW
DC-DC2
TLM
TLM
OBC
Com2
DC-DC3
OBC
CMD
uSW
Flight Pin
RX TNC
RX
ACK
TLM
Charge
Circuit
CW Gen
PWR5V
Flight Pin
Solar Cell
CW
Digital Sensors
Antenna Latch
Important Analog
Sensors
Analog Sensors
Battery
2001 University of Tokyo CUBESAT Project
■Internal Function Design Strategy
■Mother board
intervenes intersubsystem signal &
power flow．
Structure
Subsystem
Camera Module
Electronics Subsystem
Data Handling Unit
Battery
Mother
Board
Power Subsystem
Power Unit
Solar Cell
Temperature Sensors
Communication Subsystem
Communication Unit
2001 University of Tokyo
CUBESAT Project
Structure Subsystem
2001 University of Tokyo CUBESAT Project
■Structure Subsystem
1.
a)
b)
c)
d)
Body of CUBESAT
Assembly
Weight and Center Of Mass
Material
Size
3. Antennae Deployment
Mechanism
a) Magnetic Plunger
b) Folding Method
2.
a)
b)
c)
d)
Interface
Flight Pin
External Input/Output
Connector
Kill Switch
4. Strength Analysis
a) Behavior as
Cantilever Beam
b) Ceiling panel’s vibration
c) Load Estimation
d) Countermeasure
for vibration(Antennae)
2001 University of Tokyo CUBESAT Project
■Body of CUBESAT
a)
b)
c)
d)
Assembly
Weight and Center Of Mass
Material
Size
z
y
x
Center Of Mass
2001 University of Tokyo CUBESAT Project
■Assembly of XI-II
+z panel
Panels to put up solar array on
+y panel
The mainstay of XI-II
+x panel
■First, Subsystem
Boards are attached
to Mother Board.
■Then,that module is
attached to 4 pillars.
■Finally,Solar Cell
panels covered
CUBESAT’s
surface.
2001 University of Tokyo CUBESAT Project
■Construction of subsystem board
Electronic board
Power board
Communication board
Transceiver
Main motherboard
Battery box
I/F board
Sub motherboard
■Each subsystem
board is
attached to
Mother Board.
■Battery and I/F
connectors are
also attached to
Mother Board.
2001 University of Tokyo CUBESAT Project
■Center Of mass
z
y
■The difference of
geometric center
between center of mass
is 7.8mm
(within 20mm)
■Total mass is 990g
Center Of Mass(within 1kg)
x
2001 University of Tokyo CUBESAT Project
■Material
USE
Main Structure
PCB
Battery
Solar Cell
IC
PRODUCT
A7075
Glass Epoxy
Li-ion Rechargeable battery
Si-Cell
Plastic Packaged
Wiring
Teflon coated
Bolt,Nut
Antenna
Steel
Convex tape
■A7075 is the same material of P-POD which means that
thermal expansion is equal.
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)
b)
c)
d)
Flight Pin
External Input/Output
Connector
Kill Switch
2001 University of Tokyo CUBESAT Project
■Installation of CUBESAT
■3 CUBESATs can
be installed in a PPOD carrier.
■We can get some
experimental data
from I/F hole before
launch.
2001 University of Tokyo CUBESAT Project
■Interface System
Micro
Switch
V up
Switch Unit
Subsystem
Flight Pin
V down
Plunger
Antenna Deployment Order
Charge up
Switch Unit
Flight Pin 2
1
2
3
External Interface 4
5
RJ-45
6
7
8
Charge down
GND
Battery V
DCDC 5V for electronics
DCDC 5V for communication
DCDC 10V
V operate 4V
External Tx
External Rx
2001 University of Tokyo CUBESAT Project
■Mother Board
■All Subsystem Boards are
attached to Green
connector.
2001 University of Tokyo CUBESAT Project
■Interface Board
Before-Flight Pin
Kill Switch
RJ-45 Connector
■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
2001 University of Tokyo CUBESAT Project
■External Interface
No(Ext)
8,7,6,5,4,3,2,1
RJ-45 Connector
RJ-45 Plug
Name
Function
1
GND(1)
Ground
2
BATT(2)
Battery
3
E-DC(3)
4
C-DC(4)
5
Tx-DC(5)
6
EXT Tx(36)
External serial Tx
7
EXT Rx(37)
External serial Rx
8
VTO
CMOS Image sensor NTSC signal
DCDC-Converter(for Erectric
subsystem) output
DCDC-Converter(for Communication
subsystem) output
DCDC-Converter(for Telemetry
Transmitter) output
■ We use RJ-45 connector.
■ Even if CUBESAT is installed in the P-POD , we can get the
data witch the table shows.
2001 University of Tokyo CUBESAT Project
■Kill Switch
OFF
ON
Kill Switch
■We use 2 Kill Switches in parallel for redundancy.
■When one of 2 switches is ON , all system can get
power.
2001 University of Tokyo CUBESAT Project
Switch 2
Switch 1
■Flight Pin
■Switch1:Supplying power to the system.
■Switch2:OPEN/CLOSE battery charging circuit.
2001 University of Tokyo CUBESAT Project
■Antennae Deployment Mechanism
a) Magnetic Plunger
b) Folding Method
2001 University of Tokyo CUBESAT Project
■Antenna Deployment System
■Antenna is deployed using Electromagnetic Plunger
fa
+V is impressed
The piece is captured
by the magnet
Electromagnetic Plunger
fa = 3.5 [N] min.
fb = 0.8 [N]
fb
Magnetic Power decreases
And the piece is released
2001 University of Tokyo CUBESAT Project
■Antenna Deployment System
Antenna Deployment Video
2001 University of Tokyo CUBESAT Project
■Strength Analysis
a)
b)
c)
d)
Behavior as Cantilever Beam
Ceiling panel’s vibration
Load Estimation
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]
Thickness of panel
vs Harmonic frequency
1100
1080
2.5
1060
2.0
1040
1020
1.5
1000
Harmonic
Frequency
Total Mass
1.0
0.5
980
960
940
0.0
920
0.0
0.5
1.0
1.5
2.0
2.5
Thickness of panel[mm]
3.0
3.5
Total Mass[g]
Harmonic
Frequency(n=m=1)[kHz]
3.0
■ 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
2001 University of Tokyo CUBESAT Project
■Load Estimation
P-POD
■ The 3rd CubeSat experiences maximum
load while 2nd stage flight
7.7g(max)
• The maximum stress is
0.011kgf/mm2
(enough for Aluminum use)
Maximum Stress
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 Tokyo
CUBESAT Project
Electronics Subsystem
2001 University of Tokyo CUBESAT Project
■Function of Electronics
Our Works
• Health monitoring
• Command & data-handling
• Resetting DCDC
• Antenna deployment
• Controlling area sensors
Our Goals
• Satellite system management
• Capturing images with area sensors
2001 University of Tokyo CUBESAT Project
■Block Diagram
Rx-EtoC
CW-CtoE
CW-TNC
Rx-TNC
Rx-CtoE
Thermometer
0 to 7
CW-EtoC
MPX
Tx-CtoE
Tx-TNC
OBC
MPX_SEL0 ~2
Tx-EtoC
Reset Signal
E-DCDC 5V
OBC Program
&
ROM Read/Write
Pins
ROM0
ROM0
ROM0
ROM0
ROM0
ROM0
ROM0
ROM0
(Power Sub Sys.)
SEL Detect
C-DCDC 5V
To Comm
Sub Sys.
Battery Voltage
Charge Current
SCL Line
Battery Charger IC Reset Signal
SDA Line
(Structure Mother Board)
MPX
Solar Cell Current
1 to 6
2001 University of Tokyo CUBESAT Project
■Command & Data-Handling
OBC
CRNT /ROND /SOLA
TEMP /VOLT
Fixed length = 17 bytes
Uplink Command
Tx-TNC
CW-TNC
ANTD /CRNT /DCDC
MTQC /POWR/ROMD
SOLA /TEMP /VOLT
Ground Station in UT
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
3 bytes
Status
1 bytes
Picture
1 bytes
Voltage
2 bytes
Current
Additional Data
1 bytes
9 bytes
2001 University of Tokyo CUBESAT Project
■Components of Electronics
For Thermometer
JumperPin For ROM
ROM READ/WRITE Pin
For Camera
ROM Module
XI-II model
2001 University of Tokyo CUBESAT Project
■Components of Electronics-(2)
OPAmp Module
Program Pin
Thermometer Module
XI-II model
2001 University of Tokyo CUBESAT Project
■Components of Electronics-(3)
PIC 16F877
• Clock
:4MHz
• Memory
:8kword
• RAM
:368bytes
• EEPROM
:256bytes
• Operative Voltage:2.0~5.5V
ROM (24LC256)
• 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 ( LM335Z )
Thermal Sensor Calibration
Temperature[℃]
・Power consumption:5mW
・Measuring range :-40~100℃
・Characteristic
:10mV/℃
・Precision
:±1℃
40
35
30
25
20
15
10
5
0
-5
y = 99.218x - 270.29
●　data
―linearized
2.7
2.8
2.9
Voltage[V]
Monitoring
・Temperature of Battery, Solar Panel(6) and Transceiver.
・AD converting a data & sending it to comm subsystem.
3
3.1
2001 University of Tokyo CUBESAT Project
■Function of Reset-(1)
P.U. = Pull Up
P.D. = Pull Down
Tx-DC
Pch FET
e
P.D.
c
d
Tx-TNC
P.U.
a
P.U.
Pch FET
A
E-DC
b
OBC
Nch FET
SEL Detect
e
SEL Detect
CW-GEN
V in
Pch FET
A
C-DC
Rx-TNC
Nch FET
P.D.
a
b
P.U.
c
d
2001 University of Tokyo CUBESAT Project
■Function of Reset-(2)
CPU
If a=1&b=0
For SEL tolerance, reset function is needed.
Reset system requires high reliability so as
not to shut off continuously even in CPU
malfunction case.
Two wire AND reset system using FET
Switching Circuit
Vin
DCDC
• PchMOSFET
• NOT gate
2001 University of Tokyo
CUBESAT Project
Communication Subsystem
2001 University of Tokyo CUBESAT Project
■Communication System Diagram
OBC
Telemetry data
Beacon data
Morse encoder
PIC16C716
AX25 Coded data
with Parity
PLL
Control
Morse Coded data
PTT Control
Modulator
MX614
FSK modulated data
Up-link command
AD Convert
Negotiation
Tx TNC
PIC16C622
Sensors
PLL
Control
Nishi RF Lab.
Custom made
FM transmitter
Rx TNC
PIC16C711
AX25 Coded command
PLL
Control
Demodulator
MX614
FSK modulated command
Nishi RF Lab.
Custom made
CW transmitter
Nishi RF Lab.
Custom made
FM receiver
switching
Half wave length
dipole antenna
Antenna SW
Half wave length
monopole antenna
2001 University of Tokyo
CUBESAT 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
AX.25 frame structure(with Parity)
data
FCS Flag
2001 University of Tokyo CUBESAT Project
■Tx TNC Program
Start & Initialization
data from OBC ?
Yes
Receive data from OBC
Packetize into AX25 format
Send packet to FSK modulator
No
2001 University of Tokyo CUBESAT Project
■FM Transmitter
■FM Transmitter is used to transmit telemetry data
■Nishi RF Laboratory custom made transmitter
－frequency:
437.490MHz
－band width:
20kHz
－RF output power: 1W
－input power:
under 6W
－operative temp.: -30℃～+60℃
－volume:
90×60×10cm
(including CW transmitter)
FM transmitter System Diagram
FM transmitter
2001 University of Tokyo
CUBESAT 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
PIC16C716
Beacon data format
"UT1"
"www.space.t.u-tokyo.ac.jp"
"UT4"
"UT2"
time1
time2
time3
"UT5"
"UT3"
Status
Camera status
battery V
"UT6"
total I
tmp.
battery1
tmp.
battery2
tmp. battery
tmp.
battery3
tmp.
battery4
tmp. Panel
tmp.
battery5
tmp.
battery6
tmp. Panel tmp. Panel tmp. Panel tmp. Panel tmp. Panel tmp. Panel
1
2
3
4
5
6
2001 University of Tokyo CUBESAT Project
■CW Generator Program
Start & Initialization
Data Sampling
OBC ready
to send data?
No
Yes
Yes
Counter < 10sec
Receive data from OBC
Data sensing (AD Convert)
UT1 www.space.t.u-tokyo.ac.jp
UT2 AA BB CC
UT3 DD EE FF
UT4 GG HH II
UT5 JK LM NO
UT6 PQ RS TU
No
Data Sending
2001 University of Tokyo
CUBESAT Project
Command Receiving System
2001 University of Tokyo CUBESAT Project
■Rx TNC (AX.25 decoder)
■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
PIC16C711
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)
2001 University of Tokyo CUBESAT Project
■Rx TNC Program
Main Routine
Start & Initialization
Interruption Routine
A/D convert ‘Total I’
Receive Uplink command
set ‘Receiving’ flag
‘Total I’ > Threshold ?
Yes Command = “rset”
No
or flag_rst = 1 ?
No
Reset OBC
flag_rst = 0
Yes
flag_rst = 1
OBC ready to receive?
Yes
Send serial data to OBC
clear ‘Receiving’ flag
Wait 10 [ms]
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:
145.835MHz
under 100mW
under -16dBμ
16dBV typ.
-30℃～+60℃
50×60×10cm
FM receiver
2001 University of Tokyo CUBESAT Project
■Antenna Configuration
Antenna for Transmitters
430MHz band Half wavelength dipole antenna
Antenna for Receiver
144MHz Half wavelength monopole antenna
2001 University of Tokyo CUBESAT Project
■Antenna Pattern (Transmitter)
Antenna Absolute Gain
Transmitters' Half wavelength dipole Antenna
(dBm)
5.00
The gain which
we can decode
the data in our
ground station
0.00
-5.00
-10.00
-15.00
-20.00
-25.00
Gt
Gt,req
2001 University of Tokyo CUBESAT Project
■Antenna Pattern (Receiver)
Antenna Gain
Receiver's Half wavelength monopole antenna
(dBm)
-20.00
-25.00
-30.00
-35.00
-40.00
-45.00
-50.00
-55.00
2001 University of Tokyo CUBESAT Project
■Link Budget (Telemetry Tx)
Link Budget
Telemetry (TDMA)
Symbol
Unit
MHz
W
dBW
dB
deg
dB
deg
dB
dB
dBW
km
dB
dB
dB
deg
deg
dB
dB
dBK
bps
dB
Telemetry
Remark
Frequency
f
437.400
Transmit Power
P
0.600
Parameter
Transmit Power
P
-2.218
Transmitter Line Loss
Ll
-3.000 Usually -1dB～-3dB
Transmit Antenna Half-Power Beamwidth θt
110.000
Ideal dipole
Peak Transmit Antenna Gain
Gpt
2.148
Ideal dipole
Transmit Antenna Pointing Offset
et
90.000
Uncontrolled
Transmit Antenna Pointing Loss
Lpt
-8.033
Transmit Antenna Gain
Gt
-5.885
Equiv. Isotropic Radiated Power
EIRP
-11.103
Propagation Path Length
S
1439.940
50kbyte/1pass
Space Loss
Ls
-148.434
Propagation & Polarization Loss
La
-0.470 Polarization (-0.3dB)
Peak Receive Antenna Gain
Grp
12.500
GS 435HS20
Receive Antenna Half-Power Beamwidth θr
29.000
GS 435HS20
Receive Antenna Pointing Error
er
15.000
Assumption
Receive Antenna Pointing Loss
Lpr
-3.210
Receive Antenna Gain
Gr
9.290
System Noise Temperature
Ts
25.700
Data Rate
R
1200.000
MX614
Eb/N0
Eb/N0
21.390
Bit Error Rate
BER
0.000
Required Eb/N0
Req Eb/N0 dB-Hz
13.000
FSK, BER=10 -5
Implementation Loss
dB
-5.000
Margine
dB
3.390
CUBESAT
Comm. System
UT’s
Ground Station
2001 University of Tokyo CUBESAT Project
■Link Budget (Command Rx)
Link Budget
Uplink Command
Symbol
Unit
MHz
W
dBW
dB
deg
dB
deg
dB
dB
dBW
km
dB
dB
dB
deg
deg
dB
dB
dBK
bps
dB
Frequency
f
Transmit Power
P
Transmit Power
P
Transmitter Line Loss
Ll
Transmit Antenna Half-Power Beamwidth θt
Peak Transmit Antenna Gain
Gpt
Transmit Antenna Pointing Offset
et
Transmit Antenna Pointing Loss
Lpt
Transmit Antenna Gain
Gt
Equiv. Isotropic Radiated Power
EIRP
Propagation Path Length
S
Space Loss
Ls
Propagation & Polarization Loss
La
Peak Receive Antenna Gain
Grp
Receive Antenna Half-Power Beamwidth θr
Receive Antenna Pointing Error
er
Receive Antenna Pointing Loss
Lpr
Receive Antenna Gain
Gr
System Noise Temperature
Ts
Data Rate
R
Eb/N0
Eb/N0
Bit Error Rate
BER
Required Eb/N0
Req Eb/N0 dB-Hz
Implemention Loss
dB
Margine
dB
Uplink
Remark
145.835
20.000
Parameter
13.010
-3.000 Usually -1dB～-3dB
33.000
GS 144HS12
10.000
GS 144HS12
15.000
Assumption
-2.479
7.521
17.531
1439.940
-138.894
-0.470 Polarization (-0.3dB)
-2.521
Monopole
100.000
Monopole
90.000
Uncontrolled
-9.720
-12.241
31.100
1200.000
32.634
0.000
13.000
FSK, BER=10 -5
-5.000
14.634
UT’s
Ground Station
CUBESAT
Comm. System
2001 University of Tokyo
CUBESAT Project
Power Subsystem
2001 University of Tokyo CUBESAT Project
■Power Subsystem
Charge
Circuit
A
A
A
A
A
TNC
Batteries
Switching
Regulator
OBC
OBC
Switching
Regulator
Electronics
Subsystem
DCDC
Converter
Communicati
on Subsytem
Tx
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
Bass bar
■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
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
hrs
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
MM1485
•Small power dissipation
•Small package (8 pins), •Const. Voltage &
small power dissipation Current Charge Mode
•Const. Voltage &
•Pre-charge
Current Charge Mode Temperature protection
•No pre-charge func or
temperature protection
•Large package (16 pins)
and may be difficult to
assembly
2001 University of Tokyo CUBESAT Project
■Energy Consumption
Components Power[mW]
Frequency in use
OBC
sensors
Tx TNC
Tx
CW
CW TNC
Rx
Rx TNC
Camera
Magnetic Plg.
All times
All times
During downlink
During downlink
All times (ON / OFF)
All times
All times
All times
Sometimes
Antennae deployment
20
20
20
6000
300/125
20
125
20
150
800
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]
OK
■Maximum average supply power: 669[mW] >
Average consumption 616[mW]
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.
Dipole
Moment
Ground
Station
Magnetic
Field
Antennae
2001 University of Tokyo CUBESAT Project
■Torquer Sizing
Disturbance
AirDrag
Solar Pressure
Torque[Nm]
2.26E-10
1.38E-9
Gravity Gradient
To follow the change
of magnetic field
Required Torque
1.0E-6 [Nm]
1.25E-8
1.0E-6
At 800km
magnetic field
Required Magnetic Dipole Moment
0.046 [Am^2]
2001 University of Tokyo CUBESAT Project
■Permanent Magnet
Material
Alnico-5
Magnetic Dipole Moment
0.05
Size
φ4*25 [mm]
Weight
2
Residual Magnetic Flux Density 1300
[Am^2]
[g]
[mT]
2001 University of Tokyo CUBESAT Project
■Libration Damper
■Libration damper dissipates energy to stable
attitude change.
• Dissipation caused by hysteresis loss and eddy
current loss
• High permeability iron is used for the damper
• 3days are expected (8 days for worst case) to damp
oscillation
2001 University of Tokyo
CUBESAT Project
Environment Subsystem
2001 University of Tokyo CUBESAT Project
■Environmental Tests (outline)
Tried and Tested
■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)
Future Works
■ 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 XIIIα 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
Number Number Irradiation Fluence SEE Cross
of SEU of SEL time[sec]
[/cm^2]
Section[cm^2/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
F877
SEU(Ne)
SEU(Ar)
SEU(Kr)
LET=6.01
LET=15.1
LET=38.3
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
F877
C622
C774
SEUs/device/day
2.3514E-05
1.26733E-06
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
Temperature of 6-nodes
Temperature[degree C]
Height=600km
incrination =60°
6 nodes (CUBE planes)
mass density = Al density
specific heat=920*9[J kg^-1K-1]
conductivity=240[W m^-1K^-1]
ε=0.825
α=0.805
10
8
6
4
2
0
-2 0
-4
-6
-8
20000
40000
60000
time[sec]
80000 100000
T1
T2
T3
T4
T5
T6
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.)
Wires×3
CW
CW
GND
Rx-TNC
Rx-TNC
Vin(5V)
Battery
BNC→ONS
Tx-TNC
Tx-TNC
GND
OBC
OBC
flanged２
(Dsub50)
Temperature sensor
Serial
flanged２
(Dsub50)
Thermocouple sensor
9-wires
SW
flanged２
(Dsub50)
A/D
PIC
5V
flanged１
Mpx.B
2001 University of Tokyo CUBESAT Project
■Future Works
Battery ON
no
yes
OBC status(Serial)
with checking telemetry
E5V
C5V
10V
Vop
yes
Communication
system status
CW,Rx-TNC,Tx-TNC
yes
Long time
running
Executing partial test.
no
Running
OBC only
Running
Thermometer
for checking
2001 University of Tokyo CUBESAT Project
■Future Works
CW
Rx
Tx
...
...
Rx and Tx
communicate 300
times per 5 minutes
and suspend for
25 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
Wiring
RTV
Rubber
Bonding Agent
USE
Wiring
RTV
Rubber
Bonding Agent
PRODUCT
Fluorocarbon wires (Hitachi Cable Ltd.)
LTV rubber KE1204(AL or BL)
Si rubber KE9610/C-8B
SYLGARD184 ; FSXA-2869
TML
<0.1
0.597
0.846
1.740
CVCM
<0.01
0.117
0.052
0.660
WVR
0.007
0.736
0.040
※However, they are not fixed yet.
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 conditioner
HEPA Unit(SS-MAC) YAMATO science co.
2001 University of Tokyo
CUBESAT Project
Ground Segment
2001 University of Tokyo CUBESAT Project
■When can we contact?(1)
Pass time for 1 week
1000
900
Pass time[sec]
800
700
600
500
400
300
200
100
0
Simulation passage time[hr]
2001 University of Tokyo CUBESAT Project
■When can we contact?(2)
Maximum elevation angle (deg)
最大迎角
90
80
70
60
50
40
30
20
10
0
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
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
FM Packet 1200bps
CW Beacon
Uplink Command
If we can receive the CW Beacon,
we send Uplink Command once or twice a day.
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
Command
TNC-505
144MHz uplink
IC-970J
Telemetory
TNC
430MHz Telemetory downlink
MD recorder
MD recorder
430MHz CW downlink
IC-910D
PC
(Windows98)
TNC-555
CW beacon
EV-800
750FX
Signal
converter
CT17
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
3
4
TCDR
CDR
(3/19)
*postponed
5
6
7
8
9
10
FM Shipment (8/15)
FM Deadline
Mass Model Shipment
11
Launch
Long Range Comm. Experiment
EM Deadline
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), how
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
FSK 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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