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ESA EJSM/JGORadio & Plasma Wave
Instrument(RPWI)
Prag meeting 100218
Lennart Åhlén
Electric fieldsPlasma measurementsConductivities B
Plasma waves
Radio
•Backplane with power distribution, analog and digital interfaces•Board size: 20x15cm TBC•Connectors: Micro-D type•Box : 21x16x12 cm average 4.7mm wall thickness for Al.•Distance between Boards: 20mm
Main box mechanics
Power
Voltages:+3.3V Digital interface supply+1.8V Digital DPU and FPGA core supply +-8V Analog
•Software current limiters (msec turn off at latch up)•Common ground for all voltages•Only one ground in the backplane•Total power: 6.6W average 10W peak (100ms)
Instrument interfaces• Digital: Differential • Analog: Single ended (TBC)
Satellite interfaces• 2 Mbit SpaceWire• Single ended (TBC)
Radiation protection
•Spot shielding should be used for all S/C external electronics•Box and spot shielding should be used for the RPWI Box•Use of Rad Hard components•Box shielding 4.7mm•1.1 kg extra mass needed for 8mm box protection•3kg allocated by ESA for radiation shielding of RPWI
Action: Calculations of internal box radiation levels using GEANT 4
Generic Instrument
LP-PWI Bias control, LF wave analyzer and MIME
HFwave analyzer
WHY Should we use the ESA ASICs ?
•They are guarantied Rad hard•ESA will do the paper work•ESA will pay for the qualification•We will save mass (up to 650g)•We may save power that can be used for signal processing•We may save money •We can convert saved mass into antenna length•If they are not delivered in time we blame ESA for the delay
RA-PWI, RWI and LP-PWI Preamplifiers
Lennart Åhlen
LP_PWI PreamplifierSpecifications:•Switchable E-field / Density•100mW power consumption • 500kRad Radiation hardend • Positive feed back current generator•E-field:
DC-300Hz +-100V input rangeDC to 3MHz small signal bandwidth Better than 10^12 input resistance1nA – 100nA Current Bias range16 nV/sqr(Hz) noise
•Density:DC to 10kHz bandwidth10pA to 100uA input current range +-100V Voltage Bias range
New development: Find new low noise Rad hard operational amplifiersDevelop a MEMS chip including nano-switches and amplifiers
MEMS amplifier 10x10x1mm total mass 4x30g (4x250g)
RA_PWI and RWI PreamplifierFET follower or FET input negative feed back amplifier ?
•High distortion•Limited output range•Low power•Simple
•Low distortion•Medium power•Complex
Specifications:1kHz to 50MHz Bandwidth 2 nV/sqr(Hz) noise+-1V input range 100mW power consumption
Amplifier from Tohoku University 100Hz to 50MHz 0.6W
RPWI Grounding block diagram
EMC Actions.Define acceptable satellite RE and CE levels for the frequency range DC to 45 MHz.
MIL-STD-462D ECSS-E-ST-20-07C(31July2008)
1. All spacecraft surfaces exposed to the plasma environment shall be sufficiently conductive and grounded. < 5 kohm/sq
2. Small surfaces differential charging potential shall not exceed +-10 V, assuming a plasma current of 5 nA/cm2
3. The S/C structure shall not be used as return path for power and signals except for sensor signals to avoid common impedance coupling and magnetic disturbances.
4. Isolated receivers and balanced differential signals should be used as subsystem signal interfaces.
5. All active wires shall be twisted with its return wire and loops on circuit boards should be minimize to reduce magnetic disturbances.
6. The spacecraft system shall use a Distributed Single Point Grounding. 7. Secondary power shall be grounded to structure only once in each unit / experiment.8. Cable shields shall be grounded to structure ground at both ends. Shields shall not be
used as the return path for signal or power.9. Non-magnetic materials shall be used wherever possible.The use of ferro-magnetics
shall be avoided wherever possible.
10. It is recommended to use crystal oscillator controlled DC/DC converters
Experimenter EMC requirements
Develop the RPWI EMC requirements for the S/C by interaction during S/C design
Low Voltage Power Supply (LVPS)
Göran Olsson
Royal Institute of Technology (KTH)
Space and Plasma Physics
LFA + AM
+8V / -8V
SCM PREAMP
RWI Preamps
RA-PWI Preamp
LP-PWI Preamps
3.3V
LV
PS
-A
1.8V
3.3V
LV
PS
-B T
BD
LV
PS
CO
NT
RO
L &
MO
NIT
OR
ING
1.8V
3.3V
1.8V
+8V
-8V DPU
Clock, Control, Data and Emergency Power-Off, A + B
CE
B B
AC
KP
LA
NE
SCM
+8V / -8V 3.3V1.8V
LP-PWI
+8V / -8V 3.3V1.8V
+8V / -8V 3.3V1.8V RWI RA-PWI
HFA
LVPS IN RPWI JGO
Functional:
•DC power to all RPWI instruments:
• ±8V +3.3V, +1.8 V from 25-36 V input, nominal total power output: ~10 W
•CEB Form Fit:
• PCB Dimensions 200x 150 x 1.6 mm
• Component height 12 mm upper side, 3 mm lower side
• Backplane connector 160 pin, 3 row Airborn WG series
• Mass 300 g
•Primary to secondary isolation
•Temperature range: -30 °C to +50 °C operating
•Redundant DC/DC converters and digital controllers TBD
•Power Switching: 5 instruments having two to four supply voltages
•Voltage and Current Monitoring
•Overcurrent Tripping; Limits under software control
•Temperature Monitoring: DC/DC converter and SCM sensor
Performance:
•No-load Power (Including DC/DC converter, controller, monitoring and switches): 1.1 W
•Differential Efficiency: 82%
•Output Deviation: ±5% from nominal including all effects
•Output Ripple: < 5 mVrms
LVPS Requirements
Controller BFPGA
VoltageAnd
Current Monitors
(4)
PowerSwitches
(9Instruments)
Voltageand
CurrentMonitors
(24)
1.8, 3.3 V
From SCM Thermistor
FromSC28V
CEBBPLN
FromSC28V
DPU
1.8, 3.3, ±8 V
DC/DC Converter A
1.8, 3.3 V
CDPU-A Ctrl: Clock, Command, Data, EPO
DC/DC Converter B
Housekeeping
Controller AFPGA
Common-ModeFilter
Common-ModeFilter
•Redundant TBD DC/DC Converters and Controllers chained with the DPU
•Unused chain is a cold spare
•Common power bus for all instruments. Design to minimize risk of single point failures here.
•What if both chain A and B are powered? Must be survivable, but no functional requirement. - No mutual interlock implemented. Subject of further study.
•1.8 V is regulated to 1.5 V locally on each subsystem
•Power switches have turn-on ramping
•Emergency Power-Off
Common Bus
LVPS Block Diagram
Main Transformer
Sync
hron
ous
Rec
tifi
ers
Out
put
Filt
ers
•Primary to Secondary Isolation
•Double Shielding
SecondaryPrimary
Outputs:
+1.8 V, 1.1 A
+3.3 V, 1.1 A
+8 V, 350 mA
-8 V, 300 mA
Input: 27- 36 V
13-14 V DC
EMI Filter
•Full-Wave Rectification
•No Feedback from Secondary
•LC Pi Filters
Switchmode Regulator Controller
•Push-Pull
•Full-Wave
•210 kHz
Pulse-Width Modulator ‘Forward’ Converter
420 kHz
Tra
nsfo
rmer
Dri
ver
•Regulated input voltage to Transformer Driver
•Current positive feedback: Counterbalances losses in driver transistors, transformer and rectifiers.
First Stage Second Stage
Shielded Shielded
Two-stage Conversion:
Excellent input and load regulation
Low noise
Low output cross-regulation
Slightly lower efficiency
-
+
50mΩ
Internal: ±15 V
•Inrush current limiter
DC/DC Converter A/B
FPGA3.3 V
Linear Regulators:
1.5 V
2.5 V
Power Switch Control (9)
LVDS
HK Control (ADC, Mux, Gain Switch)
•System clock derived from the CDPU interface clock: 1.048 MHz
•If three consecutive samples (~15 ms) exceed the limit ► All voltages turned off for the affected instrument
Housekeeping ADC Data
CD
PU
A/B
•Instrument Power Control
•Housekeeping Control with Storage and Readout
•Overcurrent Tripping, limits under software control
•IVM: Actel ProASIC3 A3P250
•FM: Actel RTSX72
DC
/DC
A/B
Digital Controller A/B
1. DC/DC Converter, Housekeeping System and Stepper Motor Controller for EMMA, a plasma payload on the Swedish Astrid-2 satellite, launched December 10, 1998. Dimensions 177 x 134 x 16 mm. DC/DC design power 10 W. COTS components. This design has many features in common with the MMS LVPS.
2. DC/DC Converter for SPEDE, a plasma payload on the SMART-1 ESA Lunar Orbiter, launched 2003. Dimensions 71 x 44 x 11 mm. Design power is a mere 1.2 W.
Impacted on the Moon as planned on September 3, 2006.
Design Heritage
LVPS IVM on the UNH lab bench with co-delivered dummy load board
Mass
Circuit board Main Box Antennas/Sensors
Width 21cm meter g/m
Depth 15cm SCM 650
Card mass/cm¨2 0.7 SCM Harness 480 4 120
Number of cadrs 6 Preamp 100
Box mass 1000g LP-PWI 1800
Material density 2.8 LP-PWI Harness 375 15 25
Card mass 1449g Preamp 200
Box thickness 4.7mm RWI 1400
Box surface 1191cm^2 RWI Harness 120 3 40
Total Box Mass 3000g RWI Preamp 100
RA-PWI 200
Harness mass 1059g RA-PWI Harness 84 3 28
Preamp mass 600g RA-PWI Preamp 200
Sensor mass 4050g
Sensor + Box+Preamp 7650g
Total 8709g
Scientists dream receiver
A downgrade is needed for the JGO receivers.
Low and high frequency analyzers
Lennart Åhlen
TDA: Development of FPGA algorithms for digital analyzers to obtain high dynamic measurement range
JGO Scientists dream receiver
A downgrade is needed for the JGO receivers.
Dynamic range: The ratio of the specified maximum signal level capability of a system to its noise level in a record of continues sampled data.
What is required to fulfill the JGO since objective?
Questions to be answered by the RPWI scientists.
1.Ranges and overlap for the low and high frequency receivers?2.Wave-form capture?3.Low and High frequency data coverage?4.Number of parallel data channels? 5.Type of on-board data analyzes?
Low frequency receiver
• Signal processing: FFT, I/Q, Filter bank, Wavelets, PFT, • Buffer memory for wave form capture and Burst data.• Dynamic range: 80dB to ~120dB @ 100Hz bandwidth
High frequency receiver
• Burst data signal processing: FFT, I/Q, Filter bank, Wavelets, PFT, • Buffer memory for wave form capture and Burst data.• Dynamic range: 70dB to ~100dB @ 10kHz bandwidth
• Measurement range: 70dB to ~120dB @ 10kHz bandwidth • Dynamic range: 70dB to ~100dB @ 10kHz bandwidth
Under sampling high frequency receiver
• All high speed ADCs has a higher analog bandwidth than the maximum sampling rate. •This makes it possible to build HF digital receivers by use of under-sampling.•Under-sampling design approach is replacing mixer-based heterodyne receivers.•Signal processing: FFT, I/Q, Filter bank, Wavelets, PFT,
Principle of under sampling
Dual 1 0 -1 I/Q Mixer including SH
•Conventional mixer using high speed analog switches.
Antenna impedance measurements
•Net work analyzer S11 type measurements •Impedance antenna to plasma vs. frequency•Useful for side-by-side antenna comparisons