Project IceSARAndrew BrownfieldCameron Chapman

Nicholas MansJon Wehling

ObjectiveBuild 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: 75KMax: 145K

Subterranean Oceans

Fissures Ice Geysers

Project VALKYRIE

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

(Very-Deep Autonomous Laser-Powered Kilowatt-Class Yo-Yoing Robotic Ice Explorer)

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)

http://www.rfcafe.com/references/electrical/NEETS%20Modules/NEETS-Module-11-3-1-3-10.htm

• 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

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

Power Management

System

Patch/ Dipole Antenna Array

Transceiver Pulse/Signal Generator Receiver

Signal Processing and Correction

Data Processing (Matlab) SAR Image

Microwave Isolators

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

BudgetComponent 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?