Download Sussex Correlating Electron Spectrograph : CORES

Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 1 of 13
Project:
CORES
Title:
Correlating Electron Spectrograph
Document Type: Experiment Description / Interface Document
Document No:
CORES-EID-001
Issue:
1.0
Date:
26 May 2002
Pages:
13
Name & Function
Prepared by:
Checked by:
Approved by:
Paul Gough
PI for CORES
Date
26/5/2002
Signature
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 2 of 13
Document Change Log
Issue Rev
Date
Reason for Change
1.0
1.0
1 May 2002
26 May 2002
Initial Release
Revision
0 draft
1
Section
Affected
All
All
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Table of Contents
Tables of Figures & Tables
Acronyms and abbreviations
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5
1 Introduction
1.1 Purpose and scope
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6
2 Instrument overview
2.1 Scientific Objective
2.2 Instrument description
2.3 Instrument Heritage
2.4 Operational configurations
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7
3 Interface definitions
3.1 Mechanical Interfaces
3.1.1 Mass budget
3.2 Thermal Interfaces
3.3 Electrical Power Supply
3.3.1 Power profile
3.3.2 Power budget
3.4 EMC Design
3.4.1 Instrument Design Concept
3.4.2 Instrument Block Diagram
3.4.3 Susceptibility to EMC-Interference
3.4.4 Possible High EMC-Emission
3.5 Data Handling Interfaces
3.5.1 Data packet structure
3.5.2 Hardware interface
3.6 Software Interfaces
3.7 GSE Interfaces
3.7.1 MGSE
3.7.2 EGSE
4 Safety Procedures
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Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 3 of 13
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 4 of 13
Table of Figures
Figure 2.1 Instrument Functional Block Diagram
Figure 3.1 Mechanical Design
Figure 3.2 Instrument grounding scheme
Figure 3.3 TM and TC interface I/O circuit.
Page
7
9
10
11
Tables
Table 2.1 Instrument Main Characteristics
8
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Acronyms and abbreviations
AIT
ACF
CORES
DPU
EGSE
ELF
EM
FM
FOV
FPGA
GSE
HF
HK
HV
I/F
ISS
MCP
MGSE
N/A
OBDH
TBC
TBD
TBW
TC
TM
VLF
Assembling Integration and Testing
Auto-Correlation Function
Correlating Electron Spectrograph
Data Processing Unit
Electrical Ground Support Equipment
Extra Low Frequency 0-150Hz
Engineering Model
Flight Model
Field of View
Field Programmable Gate Array
Ground Support Equipment
High frequency range 0-10MHz
Housekeeping Data
High Voltage Supply
Interface
International Space Station
Micro-channel Plate
Mechanical Ground Support Equipment
Not Applicable
On-board Data Handling System
To be Confirmed
To be Decided
To be written
Telecommand
Telemetry
Very low frequency range 0-10kHz
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 5 of 13
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 6 of 13
1 Introduction
1.1 Purpose and scope
The purpose of this document is to provide an overview of the Correlating
Electron Spectrograph (CORES) instrument. This document focuses on the
equipment and software designed and manufactured in the Space Science
Centre at the University of Sussex and its interface aspects.
Section 2 presents an overall view of proposed instrument
Section 3 describes the instrument interfaces, hardware and harness with the
Electromagnetic compatibility model, from the instrument point of view being
presented in Section 3.4.
A first attempt of defining the operational environment at the different levels of
ground testing and the relevant I/F and resource requirements is given in
Section 3.7.2.
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 7 of 13
2 Instrument overview
2.1 Scientific Objective
The main purpose of CORES is to study the electron populations in the
vicinity of the International Space Station, ISS. Electron velocity distribution
functions are measured in fast time resolution as well as kilo-Hertz and MegaHertz modulations in the electrons resulting from wave-particle interactions.
Electrons in the energy range 10eV upto 10keV(TBC) are measured over a
360o field of view (FOV) with energy spectra resolved at typically at 0.1s time
resolution(TBC) with simultaneous measurements of electron modulations in
the frequency ranges: 0-10MHz(HF); 0-10kHz(VLF); and 0-150Hz(ELF).
2.2 Instrument description
CORES is a single module containing all of the components necessary for
electron energy resolving and electron detection via microchannel
plates(MCP) with associated High Voltage supplies (HV) and includes fast
processing using field programmable gate arrays (FPGA) with a
microcontroller Data Processing Unit (DPU) interfacing to the Telemetry,TM
and Telecommand,TC, interfaces, I/F of the On-Board Data Handling Unit,
OBDH.
Figure 2.1 Instrument Functional Block Diagram
Electrons are accepted over a range of energies arriving in a 360 o plane with
an acceptance of +1 or -1o (TBC) perpendicular to this plane. The electron
distribution function is simultaneously sampled by a total of 128 energy-angle
combinations, all processed by the FPGA in parallel with summed averages
read out by the DPU into the TM stream at a rate dependant on instantaneous
CORES instrument mode. Each of eight 22.5o sectors of the entrance plane
measures electrons in 16 pseudo-logarithmic energy ranges that contiguously
cover the range from 10eV to 10keV.
Space Science
Centre
University of
Sussex
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 8 of 13
Correlating Electron
Spectrograph
The main space science applications of CORES are:
1) Passive. Measurement of natural space plasma electron spectra and
wave-particle interactions at high time resolution.
2) Active. Identify the effects of electron/plasma guns/emitters and HF/VLF
transmitters on the ambient plasma and under, certain conditions, can also
provide a measurement of spacecraft potential.
Table 2.1 Instrument Main Characteristics
Parameter
General
Mass[kg]
Power[W]
Voltage[V]
Dimension[mm]
Functional
Electron Energy Range [eV]
Frequency Ranges[Hz]
Frequency Resolution [% of range]
Energy Resolution [% of each center]
Operational
Discrete Commands
TC Stream (Serial Interface)
TM Stream (Serial Interface)
TM Rates (Mode dependant)
Value
1.1 (TBC)
2(+/- 0.2) (TBC)
27.0 (+/- 4.0)
100 x 100 x 150
101 to 104
HF:0-107; VLF:0-104; ELF:0-150
3
50
1 Command [ON/OFF]
Bytes [Various-TBD]
Bytes [Various block sizes- TBD]
100bps to 100kbps
2.3 Instrument Heritage/ Implementation Schedule
The CORES Spectrograph development is funded by UK EPSRC. Scheduled
to be available for flight from summer 2003. The Correlation aspects are
derived from previous correlators on the SPREE instrument flown on STS-46,
1992, & STS-75, 1996. Sussex correlators were also included on the
OEDIPUS-C Canadian sounding rocket, 1995 and on a NASA Sounding
rocket, 1998. The Spectrograph is a 360o focusing design presently
undergoing vacuum chamber validation March/April 2002 and the MCP
Readout Electronics design is being completed May 2002, with testing starting
June 2002.
2.4 Operational configurations
The instrument has a variety of possible modes but it is expected that most
operations time will be limited to a few modes:
 OFF: The power supply to the instrument is switched off.
 STANDBY: The power to the instrument is on but HV supplies have not
been commanded on. This mode is for uploading new software, and
new FPGA configurations.
Space Science
Centre
University of
Sussex
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Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 9 of 13
CALIBRATION: This mode is for optimizing the MCP HV supply value.
LOW DATA RATE OPERATION: This mode is primarily for energy
spectra (no modulations information returned)
MEDIUM DATA RATE OPERATION: This mode is for full spectra and
modulation spectra, but summed over 10s.
HIGH DATA RATE OPERATION: This mode is for full spectra and
modulation spectra at the highest time resolution possible.
Autonomy is provided by a certain amount of artificial Intelligence included in
package used to select energy-angle zones for correlation, or for high time
resolution (high data rates) or for optimum instrument operation mode and
optimum compression algorithms.
3 Interface definitions
3.1 Mechanical Interfaces
Figure 3.1 Mechanical Design
The location for mounts & connector on baseplate is TBD. For example, as
illustrated : 4 holes located at corners of a 110 x 90mm rectangle with a
single Cannon D type connector on one face for power, TM, & TC.
3.1.1 Mass budget
Present estimate of total mass= 1.1kg (TBC)
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 10 of 13
3.2 Thermal Interfaces
Thermal contact and heat removal occurs via conduction from 100x100mm
base.
3.3 Electrical Power Supply
The DC/DC convertors have current limitation and short-circuit protection that
will protect other on-board systems against any short circuit on the CORES
instrument side. Any persistent voltage in the range between 24V and 32V
(including a short circuit of the power line) is harmless to the instrument.
3.3.1 Power profile
Switching between modes should not give inrush currents more than 1.5 *
nominal mode current. In any particular mode the current fluctuations will be
small as there are no cycled systems.
3.3.2 Power Budget
Mode:
OFF
STANDBY
ALL OTHER MODES
Power
0W
1.1W (TBC)
2.0W (TBC)
3.4 EMC Design
3.4.1 Instrument Design Concept
The experiment consists of a single unit contained in a box comprised of three
parts milled from a solid aluminium (dural) block. All voltage supplies and
DC/DC convertors are situated within this box.
3.4.2 Instrument Block Diagram
Figure 3.2 shows the instrument grounding scheme.
Figure 3.2 Instrument grounding scheme
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 11 of 13
3.4.3 Susceptibility to EMC-Interference
CORES includes sensitive preamplifiers inside the unit box, but no external
signals are applied to these. Otherwise CORES does not include items that
are susceptible to EMC-interference to a higher degree than what is normally
expected for space instrumentation electronic circuits.
3.4.4 Possible High EMC-Emission
The CORES instrument will use switched-mode low and high voltage power
supplies.
3.5 Data Handling Interfaces
3.5.1 Data packet structure
TBW
3.5.2 Hardware interface
A single connector (E.G. 15 way Cannon D type ) is used for both 28V primary
power, as well as telemetry, & telecommand data interfaces. The serial TM
/TC interface supports bi-directional asynchronous data transmission using
balanced digital voltage interface (RS-422).
Figure 3.3 TM and TC interface I/O circuit within CORES.
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 12 of 13
3.6 Software Interfaces
The CORES internal control units is based on a fast 8-bit microprocessor that
configures and controls the operation of an FPGA responsible for fast
processing (e.g. ACF) of electron arrival pulses.
The FPGA is responsible for:
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Data acquisition- receiving electron detection events from 128 energy angle zones in parallel.
Simultaneous HF, VLF and ELF frequency ranges modulation analysis
via ACF algorithms.
The DPU is responsible for:
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Data Format and TM packet building
HK monitoring - obtain HK data (test point voltage and temperature),
prepare HK-packet header
TM handling - sends formatted TM packets to telemetry subsystem
TC handling - receive TC packets, validate the contents and execute or
reject
Instrument state control - control the execution of the mode changing
commands and keep the instrument in a sensible state.
Configure FPGA on start up
3.7 GSE Interfaces
3.7.1 MGSE
N/A
3.7.2 EGSE
Hardware
The Electrical Ground Support Equipment is designed to be flexible in the way
it will be configured for the following stages of CORES instrument
development and checkout. Three major test configurations are planned:
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for instrument hardware and software development - Level A,
for instrument calibration and stand-alone checkout - Level B,
to support final testing and data "quick view" - Level C.
LEVEL A - Instrument development and manufacturing.The EGSE at this level
is mainly devoted to support the instrument development (hardware and
software) phase. For development the instrument is connected to the set of
commercial measurement equipment and board subsystem simulators.
LEVEL B - Instrument integration, calibration and testing.
This level is required to verify the complete instrument parameters fields,
including the worst test conditions and final calibrations.
LEVEL C - Final tests and instrument operation.
Space Science
Centre
University of
Sussex
Correlating Electron
Spectrograph
Doc. No.: CORES-EID-001
Issue:
1.0
Date:
26-May-2002
Page: 13 of 13
At the integration test level the EGSE will be mainly aimed a verifying the
compatibility of subsystems and capability of the instrument to perform the
pre-programmed operations.
It is expected that the EGSE will be able to support:
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preparing and sending commands to instrument (via MAIN EGSE
subsystem),
receiving and storing down link telemetry data (via MAIN EGSE or TM
source using LAN connection),
monitoring (acquisition, comparison against references and report) of
the on board HK parameters contained in telemetry data.
The EGSE will be designed such that any failure occurring in any test
configuration will not be propagated to the item under test.
The EGSE will be comprised of a Windows PC with interface board for control
of power (28V) and conversion of TM and TC signals.
EGSE software
The EGSE software will be implemented in a high level programming
language.
Application software consists of a number of concurrent tasks in charge of
performing the following functions:
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Display and Monitor HK data, with limit checking
Accept and upload TC to CORES
Display TM data numerically, with limit checks
Upload new configurations for DPU and FPGA
Multi-parameter display of TM data for quick look science during
mission.
4 Safety Procedures
All high voltages are totally internal to the CORES instrument and there are no
high potential surfaces near to the entrance apertures.
The CORES instrument presents no unusual safety aspects to spacecraft
integration engineers or instrumentation handlers.
The internal high voltage supplies are commanded on via the DPU with safety
interlock TC command sequences to prevent HV supplies being operated at
pressure levels which may damage the instrument internally.