Innovative Space/Ground
Architectures and Technologies for
NASA’s Space Network Evolution
Presentation at GSAW 2002, Los Angeles, CA
Roger Flaherty, NASA Goddard Space Flight Center
Aaron Weinberg, ITT Industries
March 13, 2002
TDRSS Provides Continuous Interface for Communications
with LEO Spacecraft and other Unique Customers
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Tracking Data
Relay Satellite (TDRS)
S-Band Single
Access (SSA)
Forward
Ku-Band Single Access
(KuSA) Return
KuSA Forward
United Sta
tes
SSA Return
S-Band Multiple Access
(SMA) Forward
Ka-Band Single
Access (KaSA)
Return Link
KaSA
Forward
SMA Return
SSA+KSA
KaSA User
Spacecraft
TDRSS
Ground
Terminal
South Pole
TDRS Relay
(SPTR)
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New TDRS H,I,J
Service
White Sands, New Mexico; 2 Sites
Guam; 1 Site
2
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Introduction
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! NASA’s Space Network (SN)has been providing global
communications/tracking support to LEO spacecraft since the
1980’s
! The SN currently includes a constellation of 7 TDRSS satellites and
3 ground stations -- existing + planned global TDRSS constellation
availability to 2012+
! Newest satellites offer broadband Ka-service
! Since its inception, SN has proven itself to be highly flexible/adaptable
and amenable to service enhancement/ augmentation via
" Technology insertion into Ground Segment and Customer Equipment
" Introduction of innovative end-to-end operations concepts
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System Architecture Overview
Indian Ocean
Reserved for
NSF Polar Science
Pacific Ocean
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Atlantic Ocean
Note: Each SGLT antenna can point to any E or W TDRS
Guam
SGLT
SGLT
SGLT
Inter-Facility
Link
STGT
SGLT
SGLT
WSGT
Mission Operations
Control Center
(MOCC)
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NASA
NCC
NASA Tracking And Data Relay Satellite (F1-F7)
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Single Access Antenna (1 of 2)
S- and Ku-Bands
S-Band Multi-Access (MA) Array
Supports High Data Rates
All elements used to support
spread-spectrum CDMA Return link
transmissions from users
- Large number of independent,
high-gain, antenna beams may
be formed at TDRS Ground
Terminal
Subset of elements used for TDRS
Forward link transmission to users
- One transmit channel at a
time
- May provide TDM data stream for
multiple users within footprint
Extremely robust; virtually no element
failures to date on all 6 satellites
Space/Ground Link Antenna
Ku-Band
Interface with NASA GT
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TDRSS Flexibility/Adaptability -- Examples of
New/Improved Services not Originally Planned
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! New Demand Access Service (DAS) via MA Return on first
generation (up to 19 year old) spacecraft
" Expansion of ground-beamforming capacity permits dramatic growth of random-access
users (e.g., for emergency 911; science alerts)
" Cost-effectiveness/high-performance via new technology insertion
! Evolution to integrated FWD/RTN DAS
! Bent-pipe satellite permits waveform evolution -- accommodated by
!
!
!
!
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software-programmable upgrades in ground station
Distinct customers simultaneously supportable via one multi-band
SA antenna -- e.g., Space Station @ Ku-band and attached payload
at S-band
Formation-flying/spacecraft-cluster supported via SA antenna
Launch Vehicle, Range Safety support via SSA
Remote operations/control of Guam ground station
6
New Demand Access Service (DAS)
NASA currently developing Demand Access Service
(DAS) that can greatly benefit emerging LEO spacecraft
Users -- Operational by 4th Qtr 2002
! Reduced LEO spacecraft power consumption
! Increased LEO spacecraft operational flexibility and autonomy
! Reduced operational overhead
! Introduction of unique service support capabilities – e.g.,
immediate accommodation of science alerts; emergency 911
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Third Generation Beamforming Subsystem (TGBFS)
-- Augmentation to Original Ground Equipment
RF FDM Signal ( Element
Signals Multiplexed)
New Beamformers
(6 BF’s per chassis)
- Multiplexing
- Covariance Matrix
Generation
Existing
Equipment
# A/D Conversion
# Beamformers
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Digital I/Q
Element
Signals
Element
Element Multiplexer/
Multiplexer/
Correlator
Correlator (EMC)
(EMC)
.
.
.
CP 1 2 3 4 5 6
CP 1 2 3 4 5 6
Demods
CP 1 2 3 4 5 6
CP 1 2 3 4 5 6
Demods
CP 1 2 3 4 5 6
CP 1 2 3 4 5 6
Demods
CP 1 2 3 4 5 6
CP 1 2 3 4 5 6
Demods
# Calibration
D
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B
U
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I
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Calibration
Vector
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•
•
Third Generation Beamformer System (TGBFS)
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! Element Multiplexer / Correlator (EMC)
" MA Data Input: digital I/Q signals (on parallel ribbon
cables) plus an ethernet connection
" Operations: Multiplexing, covariance matrix
generation (for adaptive beamforming), and
calibration vector computation / distribution
" MA Data Output: MA element signals (on Fibre
channel cables) plus an ethernet connection
" 7 EMC’s manufactured and shipped
" Operational
Key Building Blocks for the NASA Demand Access System
!
Individual Beamformer Unit Group (IBUG)
6 Individual Beamformer Units (IBUs) per IBUG, 19”
chassis
" User control independent of NASA operations
" Order of magnitude reduction in cost / size relative to
existing (second generation) beamformer
" Available as a COTS Product, ≤120 day delivery
"
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Illustrative System Architecture and Operations Concept for
Autonomous, Two-Way Demand Access User Operations
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Multi-User (e.g., Formation Flying) Support
GPS
TDRS
•
S-band Broadcast
• CDMA; Commands/Msg’s,
L
CDMA Transmissions -Synchronous, Asynchronous
TDRSS
Ground
Terminal
User
Command
Center
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Evolution to Low Power Transceiver (LPT) via Leveraging of
Heritage and State-of-Art Technology Insertion
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Highly
Programmable
Ground
Terminal
Receiver
(SPAR)
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Programmable
Transceiver
for Space
Station
(ECOMM)
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Modular architecture permits adding PC-104 cards to
card stack (e.g., to add wideband Ka-band)
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Overview of LPT Applications
GPS
•
•
•
•
Candidate
Users
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•
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Illustrative Configuration
LPT
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Ongoing LPT Activities
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! Third Generation Engineering Model ~ 3/02
" Focus on space qualification
! Near-term Shuttle flight experiments -- CANDOS, 7/02
" Reconfigurability
" Integrated TDRSS/GPS operation
" Range-safety
! Formation-flying / TechSat 21 – Air Force Research Labs
" 3 spacecraft formation
" LPT will provide: space/ground comm; GPS; crosslink comm and relative nav
" Flight in 2006
! Other NASA, AFRL flight missions under consideration
! Ongoing miniaturization, power reduction
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