Project IceSAR
Andrew Brownfield
Cameron Chapman
Nicholas Mans
Jon Wehling
Objective
Build and test a Synthetic
Aperture Endfire Array Radar in
order to reconstruct 3D image of
the terrain in front of the
spacecraft.
Enceladus (moon of Saturn)
Mean radius
252.1 ± 0.1 km (0.0395
Earths)[7]
Mass
(1.080 22 ±
0.001 01) × 1020 kg[7]
(1.8×10-5 Earths)
Surface temp.
Kelvin[10]
Average: 75K
Max: 145K
Subterranean Oceans
Fissures
Ice Geysers
Project VALKYRIE
(Very-Deep Autonomous Laser-Powered Kilowatt-Class Yo-Yoing Robotic Ice Explorer)
NASA’s Request For Proposals
VALKYRIE – collaborations
between Stone Aerospace and
Professor Gasiewski
Request for prototype to
Antarctica
From there the design goes to
Enceladus
VALKALRIE’s obstacle avoidance
Radar driven obstacle avoidance
•
•
Use radar to see rocks through ice
– 500MHz needed
Space issues
– Patch or dipole antenna
Patch Antenna Radiation
Dipole Antenna Radiation
Accurate object detection requires sufficient resolution, either through a scanning
focused beam or by utilizing SAR to synthetically narrow the beam
Synthetic Aperture Radar (SAR)
• Using the Range Gating
Principle it is possible to
calculate the distance to
an object
• The magnitude and phase
of the return signal at
multiple positions allows
for the reconstruction of a
radar image and relative
position of the object in
3D space
http://www.rfcafe.com/references/electrical/NEETS%20Modules/NEETS-Module-11-3-1-3-10.htm
Synthetic Aperture Radar (cont.)
• A single broad radar pulse will provide general distance information, but
no direction, due to azimuthal ambiguity
• Multiple pulses from different locations provide a tool for determining
direction, thus effectively narrowing the beam width
• By sampling many times in a flyby plane or satellite, one can sweep out
large tracts of information, with each point on the ground generated with
many different radar pulses.
www.skylondaworks.com/sc_sar0.htm
VALKYRIE’s SAR
• Probe moves towards the objects it’s
detecting, not orthogonal to it
• Complex algorithms to determine
relative position of an object
• 4 antennae are not pointed
orthogonally or parallel, but tilted
and concentrically oriented around
the nose of the probe
High Level Systems Layout
Solid Objects
Patch/ Dipole
Antenna Array
Microwave
Isolators
Power
Management
System
Transceiver
Pulse/Signal
Generator
Receiver
Signal Processing
and Correction
Data Processing
(Matlab)
SAR Image
Transmitter
• 100W transmission power
– Sin wave generator (500MHz)
– 30ns Pulse (gated switch)
– Amplifier
Antenna
Dipole
• Omnidirectional Radiation
• Compact
• Backplane λ/4 separation to
partially direct the beam
Microstrip patch
• Hemispherical radiation
• Backplane next to patch
• Each patch must be λ/2 in
length
Receiver
• Receive a radar pulse with 2km pathlength
• Isolator (Protection against transmitter
feedback)
• Magnitude and Phase
Computer Interface and Control
• FPGA Altera board NIOS II core
– Monitor power
– Control Radar pulse width and Range-gating of
received signals
• National Instruments Data Acquisition (DAQ)
PCI board.
– Desktop interface and file storage for post
processing
Software
Post Process
• Matlab image processing of
CSV file.
• SAR algorithm processing to
reduces azimuthal
ambiguity in radar
Interface
• Altera development
software
• NI board software
• C based GUI
Power
• Bench-top devices
• Regulated DC for FPGA
• Power through the National Instruments card.
Division of Labor
•
•
•
•
Cameron-FPGA Programming
Jon-Signal Processing
Andrew-Antenna Design
Nick-Hardware Integration and Testing
Preliminary Schedule
• Highly Modular
• Plan on having hardware completed by Milestone
1
Risks and Contingency
• Learning curve - Relatively inexperienced with
antennas/radar
• NTIA regulations - frequency control
• Broadcast around 500MHz (Transparent
frequency of Ice)
• High Cost - Much covered by Stone Aerospace
• Build vs. Buy
• Time - Complex integration/ functional testing
Budget
Component
Estimated Cost
Receiver
Unknown
Transmitter
Unknown
FPGA
$80
Antennae
$100
NI interface card
$500
PCB
$100
Misc Parts
$100
Power
$50
Total
$1000+
FIN
• Questions?