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VLF Interferometer. Defense University Research Instrumentation Program (DURIP). Project Advisor: Umran Inan Project Team: Jeffrey Chang, Katie Braden, Timothy Chevalier, Andrew Park, Joseph Payne. What Is the Interferometer?.
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VLF Interferometer Defense University Research Instrumentation Program (DURIP) Project Advisor: Umran Inan Project Team: Jeffrey Chang, Katie Braden, Timothy Chevalier, Andrew Park, Joseph Payne
What Is the Interferometer? • Nine element array of time synchronous receivers. • Capable of simultaneous recording in 3 channels, like an expensive VCR. • Low power, battery operated, standalone units. • Modular design for easy upgrade.
Purpose of Interferometer • Measure near field of HAARP modulated electrojet currents. • Determine spatial distribution of currents. • Help to maximize ELF/VLF wave production. • Standalone receiver that can truly be deployed anywhere anytime.
Validate Sampling method Test Connection to CF media. Fix any gotchas Cleanup design Improve Stability Get ready for Production Interferometer V2.0 Version 1.0 Version 2.0
Interferometer Capabilities • Capture from ~100 Hz to ~10 kHz. • Upper bound is largely variable by changing filter and sample rate. • Sensitivity of 1.5*10-6 v/m-Hz-1/2 at 1khz. • Low power consumption, ~6W. • Store 1 GB of data.
Block Diagram of Receiver Antennas Line Receiver Clipper Anti-aliasing LPF Filter Preamplifier 16-Bit A/D (250 ksps) Preamp 1GB Storage Device CPU (i386) Control Logic (FPGA) UT+ Oncore GPS Modem? Line Receiver
Time Synchronization 1PPS GPS Clock Control Signals FPGA 16-Bit A/D Temp. Controlled Crystal Osc. ~10MHz Control Signals Data Bus i386
Main Equipment • Tern i386 controller. • IBM Microdrive. • Motorola Oncore UT+.
Equipment Cont. • 1 x 6V, 189 A-Hr Batteries 2 x 12V, 55 A-Hr Batteries • Laptop. • Wagon!
Preamp Cards • Matches the impedence of the square loop antenna with a transformer. • Amplifies and filters signal. • Output driver with a transformer.
Motherboard • Voltage regulation. • Mounts for CPU and GPS cards. • FPGA for glue logic. • ISA type slots for adapter cards.
CPU Card • Manufactured by Tern. • I386 u-controller with lots of goodies… • Two serial lines, one for programming, one for LCD display and GPS. • 16 Bit data bus, 7 Bit Addressing (but word access only) • Port pins as CS for ADC or CF card.
GPS Card • Motorola Encore GPS card. • Small form factor. • For timing use, +/- 500ns timing accuracy. • Serial I/O
Filter Card • Instrumentation Amplifier – differential input to single ended output. • Selectable 8 pole or 16 pole Chebyshev filter. • Selectable output gain from unity to 40dB.
CF Storage Card • CF connector, capable of docking with both Type I or Type II CF cards. • CF cards in IDE mode. • Otherwise, nothing special. • Future version might have two flash card slots on it.
Sampling Card • 3 LTC1606 ADC chips, simultaneous sampling (rated @ 250 ksps each). • Sampling controlled by FPGA, with CS from processor. • 16 bit tri-state buffers as hacked remedy to power problem • Temperature controlled oscillator…for accurate timing.
HAARP Near transmitter Power lines nearby Lake Louise & Paxton ~45 Minutes away In the middle of no-where No power lines nearby Low Noise Locations