Transcript Achieving Real-Time Pulse-to

Achieving Real-time
Pulse-to-pulse
PRI Prediction
By Rémi Gauvin
B.A.Sc. Computer Engineering
MC Countermeasures Inc.
Objectives
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Radars and Current ECM Overview
What is PRI Prediction and its Benefits?
How PRI Prediction is Achieved
Results Obtained
Conclusion and Future Look
July-15
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Introduction on Radars
• Pulsed Doppler Illuminator
• Constant PRI
• High PRI Pulsed Doppler
• Constant PRI and Dwell-Shift
• Medium PRF Pulsed Doppler
• Staggered PRI (few stagger levels)
• Low PRI Pulsed Doppler
• Staggered PRI
• Low PRF Radars
• Complex PRI Patterns
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PRI Pattern Modulations
PRI Pattern Modulation
Constant
Dwell-Shift
Staggered
Wobulated
Sliding
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8
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PRI #
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Current ECM: Noise Jamming
• Noise masks out the target return
• Good against older non-coherent radars with
wide instantaneous bandwidth
• Unsuccessful against:
• Burst-to-burst RF agile radars
• Coherent processing Radars with narrow
bandwidth Doppler filtering
• Noise jamming with fast tuning oscillator
may be ineffective due to low tuning accuracy
July-15
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Current ECM: Deception
Using Analog Delay Lines
• Analog delay lines holds the Radar pulse to
create a delayed copy
• Down range false targets only
• RGPO: Range Gate Pull Out technique
• Radar’s MTI Filter follows the false target instead
of the target return.
• Noise accumulates quickly in the delay line
making the technique limited to only a few s
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Current ECM: Deception
Using DRFM’s
• Digital Radar Frequency Memory (DRFM)
• Store the Radar pulse indefinitely
• False Target Position can be anywhere for constant
PRI modulation
• Range Gate Pull Out and Range Gate Pull In
Technique are possible
• Problem: Non Constant PRI Modulation Limits the
False Target Position to Down Range
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Solution: PRI Prediction
• Pulse Repetition Interval (PRI) Prediction
consists of estimating the time of arrival
(TOA) of the next Radar pulse
• Paired with a DRFM based system a PRI
Predictor can produce targets over the full
PRI range
Staggered PRI Pulse Train
PRI A
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PRI B
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PRI C
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Constant PRI
Constant PRI Pulse Train - Up Range Target
PRI A
FT
False Target Delay
PRI B
Range 1
FT
False Target Delay
PRI C
Range 1
FT
False Target Delay
Range 1
False Target can be positioned anywhere
with or without prediction
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Non Constant PRI
without Prediction
Staggered PRI Pulse Train - Up Range Target without Prediction
PRI A
FT
False Target Delay
PRI B
Range 1
FT
False Target Delay
PRI C
Range 2
FT
False Target Delay
Range 3
Without prediction the false target position is limited
to down range for non-constant pattern modulation
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Non Constant PRI
with Prediction
Staggered PRI Pulse Train - Up Range Target with Prediction
PRI A
FT
False Target Delay 1
PRI B
Range 1
FT
False Target Delay 2
PRI C
Range 1
FT
False Target Delay 3
Range 1
With prediction the false target can now be positioned
correctly anywhere regardless of pattern modulation
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Other Advantages of
PRI Prediction : Fades
• Production of false targets during signal fades
or receiver blanking
Receiver blanked
Staggered PRI Pulse Train
PRI A
PRI B
False Target Pulse Train
PRI C
PRI A
PRI B
PRI C
• Even though the video signal is blanked the false
targets are still produced in their correct position
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Other Advantages of
PRI Prediction: Filtering
• Improved filtering of multiple signals with the
use of time gating principles
Staggered PRI Pulse Train
PRI A
Extra Pulse
PRI B
PRI C
• Knowing when the next pulse should occur allows
the system to write only valid pulses in the DRFM
and trigger false targets only on valid pulses
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Difficulties in PRI Prediction
• Data rate (PRI’s range for 2 s to 15 ms)
• Corrupt data
• PRI pattern containing extra pulses
• PRI pattern missing pulses
• Interleaved patterns
• Multiple radars in band
• Noise in band
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To Make PRI Prediction Work
• A System must:
• Track various modulation type such as:
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Constants, Dwell-Shifts, Staggered, LinearSliding and Wobulated (Sinusoidal)
Base prediction on real-time data
Perform real-time pulse-to-pulse analysis and
prediction
Have minimal sensitivity to spurious and missing
pulses
Have the ability to keep track through signal
fades
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Multiple Thread Solution
• MC-CM Adaptive Prediction Scheme
• The system has a Multiple Instruction Single Data
(MISD) Structure and runs a variety of predictive
algorithms on different threads
• The algorithms learns the pattern and issues
predictions in real-time on pulse-to-pulse basis
Get New
PRI Data
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PRI Pattern
Recognition
and History
Analysis
Estimation of
Next PRI
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Send PRI
Prediction
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Typical Prediction Process
• Predictions for upcoming PRI’s originate
from associating individual weights to
different PRI’s accumulated over the last
while
n 1
PRIn1 Wk  PRIk
k m
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Multiple Thread Solution (2)
Process 1
Process 2
PRI
Prediction
Arbitrator
PRI Data
Acquisition
Predicted PRI
...
Process N
Process Configuration
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PRI Prediction System
Detected
Video
PRI Measurement
PRI Data
RF Tag
(Optional)
PRI Prediction Core
Write
Command
PRI Prediction
Technique
Generator
Configuration
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Technique Generator
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False Target
Read Strobes
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Available Form Factors
• 4 x 4 inches
• USB Interface
July-15
• 3 x 3 inches
• Serial Interface
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Performance vs. Constants,
Dwell-Shifts and Sliding
• Accurately tracks the PRI after a few pulses
• PRI can range from 2 s to 15 ms
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Performance vs. Staggered
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Performance vs. Wobulated
• Tracks after 100 to 150 PRI’s (Typically)
• Min PRI of 75 us, Max Deviation +/- 50 %
• As little as 4 PRI per cycle required
Wobulated Pattern Modulation
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60
70
80
90
100
PRI #
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Random Pulse Drop Outs
Effect of Random Pulse Drop Outs
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100
80
60
40
% of Pulses Seen
% of Correct False Targets
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10
15
20
% of Random Pulse Drop Out
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30
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Conclusion
• PRI Prediction improves ECM Effectiveness
• False target production is possible over full range
of the PRI regardless of the PRI pattern
modulation
• Can produce false targets during signal fades and
receiver blanking.
• Sorts unwanted information from DRFM with
time gating principles
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Future
• What is next:
• Pulse de-interleaving using RF data to isolate a
single emitter out of many
• Tracking and jamming multiple emitters
simultaneously or in a time shared fashion
• Improved tracking and acquisition of various
modulation types in a corrupt environment
July-15
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Acknowledgements
Special thanks to :
• Scott McDonald
• Ken McRitchie
• Dan Grise
For information, resources and work performed
on the PRI Predictor line of systems
July-15
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? Questions ?
For further information, please feel free to contact us at:
MC Countermeasures Inc.
39 Robertson Road, Suite 256
Nepean, Ontario, K2H 8R2 Canada
Tel: +1 (613) 721-1552
Fax: +1 (613) 721-1553
http://www.mc-cm.com
[email protected]
THANK YOU FOR YOUR ATTENTION
July-15
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