VLF 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
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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.

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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.

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Interferometer V2.0
Version 1.0
Version 2.0

• Validate Sampling method
• Test Connection to CF media.
• Fix any gotchas

• Cleanup design
• Improve Stability
• Get ready for Production

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Arrangement of Interferometer
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Interferometer Capabilities

• Capture from 100 Hz to 10 kHz.
• Upper bound is largely variable by changing
  filter and sample rate.
• Sensitivity of 1.510-6 v/m-Hz-1/2 at 1khz.
• Low power consumption, 6W.
• Store 1 GB of data.

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Block Diagram of Receiver
Antennas
Line Receiver
Clipper
Anti-aliasing LPF Filter
Preamplifier
16-Bit A/D (250 ksps)
Preamp
Control Logic (FPGA)
CPU (i386)
1GB Storage Device
UT Oncore GPS
Modem?
Line Receiver
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Time Synchronization
1PPS GPS Clock
Control Signals
FPGA
16-Bit A/D
Temp. Controlled Crystal Osc. 10MHz
Control Signals
Data Bus
i386
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Main Equipment

• Tern i386 controller.
• IBM Microdrive.
• Motorola Oncore UT.

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Equipment Cont.

• 1 x 6V, 189 A-Hr Batteries
• 2 x 12V, 55 A-Hr Batteries
• Laptop.
• Wagon!

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Preamp
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Preamp
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Preamp Cards

• Matches the impedence of the square loop antenna
  with a transformer.
• Amplifies and filters signal.
• Output driver with a transformer.

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Line Receiver
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Motherboard
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Motherboard

• Voltage regulation.
• Mounts for CPU and GPS cards.
• FPGA for glue logic.
• ISA type slots for adapter cards.

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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.

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GPS Card

• Motorola Encore GPS card.
• Small form factor.
• For timing use, /- 500ns timing accuracy.
• Serial I/O

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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.

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Sample Filter
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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.

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Sampling Card

• 3 LTC1606 ADC chips, simultaneous sampling (rated
  _at_ 250 ksps each).
• Sampling controlled by FPGA, with CS from
  processor.
• 16 bit tri-state buffers as hacked remedy to
  power problem
• Temperature controlled oscillatorfor accurate
  timing.

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Locations

• HAARP
• Near transmitter
• Power lines nearby

• Lake Louise Paxton
• 45 Minutes away
• In the middle of no-where
• No power lines nearby
• Low Noise

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HAARP Setup
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HAARP Setup
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Lake Louise
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Lake Louise
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Lake Louise
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Lake Louise
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Lake Louise
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HAARP SU Data
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HAARP SU Data
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HAARP SU Data
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Lake Louise SU Data
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Lake Louise SU Data
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Lake Louise SU Data
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HAARP AU Data
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Lake Louise AU Data