Transcript AGI conference presentation

Modeling GPS Adaptive Nulling
Receivers
Ken Sherman (Satellite Software),
Haroon Rashid (AGI), Trevor Stief (AGI)
AGI
Pg 1 of xx
www.agiuc.com
Satellite Software
• AGI business partner specializing in antennas
• Develops antenna modeling software (SATSOFT)
• Developing a series of antenna plug-ins for stk &
ntk
• www.satsoft.com
• Contact Ken Sherman (sales at satsoft dot com)
AGI
Pg 2 of xx
www.agiuc.com
Overview
• Plug-In Architecture
• Array Design
• PA GUI
• Nulling Algorithms
• Null Formation
• Scenarios
• Results
• Future Work
• Conclusions
AGI
Pg 3 of xx
www.agiuc.com
Antenna Plug-In Architecture
stk GUI
Panel
2D/3D
Contours
Link
Analysis &
Reports
Receivers,
Transmitters
& Jammers
STK
Plug-In
Plug-In
GUI
Antenna
Geometry
Analysis &
Pattern
Computation
Pattern
Contours
AGI
Pg 4 of xx
Antenna
Beamformer
Pattern
Cuts
www.agiuc.com
Wide Range of Antennas
Supported by Plug-In
• Active & passive receiving antennas
• Active & passive transmitting antennas
• Beam steering and nulling
• Arbitrary polarization (LP, CP, etc)
AGI
Pg 5 of xx
www.agiuc.com
Active Receiving Antenna
Receiver
Equivalent Active Antenna
Lossless Antenna

L1
F1, G1
t e  ( l1  1) t 0  ( f 1  1) l1 t 0  ( l 2  1)
g ckt 
AGI
g1
l2
g a  ,   
g lossless  ,  
l1
Pg 6 of xx
L2
l1
g1
Lr
t0
fe  1 
te
t0
www.agiuc.com
Features of Phased Array Plug In
• Quickly design arrays for any receiver or transmitter in stk &
ntk
• Planar, linear, and cylindrical (conformal) array geometries
• Circular, elliptical, and polygonal apertures
• Shaped beam phase and/or amplitude synthesis
• Adaptive nulling
• Taylor circular, rectangular, and Baylis low sidelobe
aperture tapers
• Several element models
• Linear & circular polarization
AGI
Pg 7 of xx
www.agiuc.com
Designing & Analyze the Array
Define:
• Size & shape of aperture
• Number & position of elements
• Type of radiating elements
• Nulling algorithm, if any
Perform:
• Static pattern analysis
AGI
Pg 8 of xx
www.agiuc.com
Phased Array User Interface
AGI
Pg 9 of xx
www.agiuc.com
Adaptive Nulling Algorithms
• LMS steepest descent
• Howells-Applebaum
• Sample Covariance Matrix Inversion
AGI
Pg 10 of xx
www.agiuc.com
Forming a Pattern Null
AGI
Pg 11 of xx
www.agiuc.com
STK Scenarios
• SATCOM Link with Jammer on Airplane
• GPS receiver with single jammer
AGI
Pg 12 of xx
www.agiuc.com
-30
-20 -30
-20
Un-Adapted Pattern
-30
-30
-20
-20
-2
-20
-30
18.77
-30
-20
-1
-20
-20
-3
-5
-10
-20
-30
-30
-20
AGI
Pg 13 of xx
www.agiuc.com
-20 -30 -30
-30
-30
Adapted Pattern
-30
-20
-30
-30
-30
-30
-30
-30
-30
-20
-20
-5
-3
Jammer
-20
-30
16.85
-20
-20
-20
-20
-1
-2
-20
-10
-20
AGI
-20
-30
-30
-10
Pg 14 of xx
www.agiuc.com
3D Antenna Pattern
AGI
Pg 15 of xx
www.agiuc.com
Future Work
• Phased array digital beamformer
• Phased array interface to future stk/radar module
• Reflector model (physical optics)
• Wire antenna model (moment method)
• Scripting (nulling algorithms, etc)
AGI
Pg 16 of xx
www.agiuc.com
Conclusions
• Flexible antenna plug-in architecture for stk & ntk
• New phased array plug-in under development
• Improvement of s/n by nulling a jammer
• Future work
Challenges:
• Accurate gain = pattern integration = cpu time
• Providing visual feedback
• Easy-to-use but comprehensive GUI
AGI
Pg 17 of xx
www.agiuc.com