A UWB TDOA Two-Point-Tracking System has been conceived and developed at JSC. This system can provide sub-inch tracking capability of two points on one target. This capability can be applied to guide a docking process in a 2D space. Lab tests demonstrate the feasibility of this technology

Arndt, Dickey

Dekome, Kent

Dusl, John

Ngo, Phong

Ni, Jianjun David

Phan, Chau

NASA Technical Reports Server

Ultra-Wideband Time-Difference-Of-
Arrival Two-Point-Tracking System
Jianjun (David) Ni
David ni 1@nasa gov 281 483 1467. - . , - -
Dickey Arndt, Phong Ngo, Chau Phan, Kent Dekome, John Dusl
UWB Systems Group / EV4
Avionic Systems Division / EV
NASA Johnson Space Center
    
2009-05-15 AIAA Houston Annual Technical 
Symposium 2009
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https://ntrs.nasa.gov/search.jsp?R=20090020676 2019-08-30T07:09:35+00:00Z
Outline
Motivation
TDOA Tracking Methodology
Analytical Tracking Resolution
Fine Time Resolution of UWB Pulses
Lab Tests of the Prototype System
Summary
Future Work
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Symposium 2009
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M ti ti
UWB TDOA high resolution proximity Tracking System (developed at JSC) provides sub-inch 
o va on
tracking resolution for Honeywell’s robotic control system [1].
This system can be enhanced with two-point-tracking capability and applied to the docking 
process of the Lunar rover Chariot for the battery charging.  
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Ti Diff f A i l (TDOA)me erence o  rr va  
Hyperbola: b2 x2 - a2 y2 = a2 b2  
Tx
Rx1 Rx2
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Ti Diff f A i l (TDOA)me erence o  rr va  
Rx1
(x1, y1)
Rx2
(x2, y2)
Rx3
Tx
(x y)
(x3, y3)
, 
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Advantages of TDOA
No synchronization between Tx and Rx     
Simplex (one-way) data estimation
TDOA estimates can be obtained     
through Cross-Correlation plus Peak 
Detection (CCPD) 
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Resolution Analysis (setting)
Tx
r0
ri
r θ
iφ
R2 R1r
R0
R3
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Proximity High Resolution [1]
2 2MSE 4
2
c
c
σ
ε σ
≈
=
83 10 m/sc = ×  
910  s = 1 ns,  0.6 mσ ε−= =
1110  s = 10 ps,  0.006 mσ ε−= =
2009-05-15 AIAA Houston Annual Technical 
Symposium 2009
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What is UWB ? (FCC Definition)
A ultra wideband device is defined as any device        
where the fractional bandwidth is greater than
0.20 or occupies 500 MHz or more of spectrum.
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Wh  UWB ?y
Immunity to interference from narrow band RF systems due to ultra-wide bandwidth
Low impact on other RF systems due to extremely low power spectral densities
Capable of precise tracking due to sub-nanosecond time resolution
Robust performance in multipath environments
High data rate communication (100 Mbps and higher)
UWB Fine Time Resolution Resolving between direct vs. multipath components 
is possible with extremely narrow UWB pulses2009-05-15 AIAA Houston Annual Technical Symposium 2009
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System Configuration 
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TDOA Proximity Tracking (1R 4A set p)x -u
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TDOA Estimate (from 8 pulses)
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Docking Process Guided by Two Point Tracking- -
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Summary
A UWB TDOA Two-Point-Tracking System has been 
conceived and developed at JSC.
Thi  t   id  b i h t ki  s sys em can prov e su - nc rac ng
capability of two points on one target.
This capability can be applied to guide a  docking 
process in a 2D space.
Lab tests demonstrate the feasibility of this 
technology. 
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Symposium 2009
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Future Work
Future work includes expanding 
the tracking area to the size of 
Chariot docking site and test the 
docking process with the actual 
di i  f th  Ch i t b tt  mens on o e ar o a ery
charging station.
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Symposium 2009
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References
[1]. Jianjun (David) Ni; “UWB TDOA Proximity 
High Resolution Tracking System”, IEEE 
Symposium for Space Applications of Wireless & 
RFID (SWIRF), Houston, TX, May 2007.
2009-05-15 AIAA Houston Annual Technical 
Symposium 2009
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Ultra-Wideband Time-Difference-of-Arrival Two-Point-Tracking System

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