Single Antenna Geo-location Based on Signal Structure

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Single Antenna Geo-location Based on Signal
Structure
(Free space Radio Signals)

• Elad Tzoreff, Ben-Zion Bobrovsky, Anthony J.
  Weiss

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Background Common Geo-location methods

• Direction of Arrival (DOA)
• Time Difference of Arrival (TDOA)
• Differential Doppler (DDOP)
• Received Signal Strength (RSS)
• Finger Printing
• Combinations of the above

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TDOA
RSS
DOA
DDOP
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Common Geo-location methods

• Multiple sensors
• Synchronization between sensors
• Communication between sensors
• All these mean
• Complex system architecture
• Expensive support systems

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We are interested in simplifying geo-location
system, but how?
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Observation

• Most radars are periodic or at least predictable

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Digital Communication Signals

• Communication Carrier is periodic
• Communication symbols appear periodically
• Communication synch frame appear periodically
• Spreading code is periodic

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Basic Idea and Advantages

• Use a single moving receiver for location
• Low cost
• Low weight
• Easy to hide (small, passive, moving)
• Simple to implement
• No synch. between sites
• No data link between sites
• Can enhance existing system

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Potential Platforms
UAV
UAV
Localization shell
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Localization Based on Signal Structure
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TDOA Lines of Position
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The LOPs Associated with DTOA
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DDOP Lines of Position
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LOPs Associated with DDOP
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Potential Obstacles

• Transmitter Oscillator instability
• Receiver clock instability
• Receiver Position inaccuracy
• TDOA/DDOP measurements errors (Noise, BW,
  Multipath)
• Transmitted signal is too short

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Oscillator Imperfection Timing Errors
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Oscillator Instability
Timing error

• Voltage controlled
• Temp. compensated
• Oven compensated

h Random error intensity
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Simulation Results
Sensor trajectory 6 Km Signal period 10
ms Sensor speed 300 m/s
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Heat Map straight trajectory
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Heat Map Curved Trajectory
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At High SNR Accuracy is Limited by Oscillator
Instability
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The Slower the Receiver Moved the Larger the error
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For Good Oscillators the Accuracy is Determined
by SNR
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Thank you, Questions, Comments or remarks?
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Direct Position Determination

• The Common Approach is a 2 Step Procedure
• Estimate parameters (TDOA, DDOP)
• Estimate Location from first step results
• The Justifications
• Easier to understand.
• less communication between stations!!!
• Asymptotic equivalence Extended Invariance
  Principle (EXIP Stoica Soderstrom 1989)

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Common Approach for Location Estimation
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Other Drawbacks
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Direct Position Determination

• Exact Maximum Likelihood
• Simple 2D search (only 2 parameters are
  estimated)
• No processing required at remote stations
• Better accuracy at low SNR or interference
• No association problem

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The DPD Heat Map
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Can we do better than DPD ?