ContentsSeaborne Passive Radar: An Initial

Investigation

Dr. Francois Maasdorp

Dr. Craig Tong

Christo Cloete

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Short Bio

• Francois received his B.Eng (electronics) (2001) and M.Eng (cum

laude) (2008) degrees from the University of Pretoria and his PhD

(2015) at the University of Cape Town, South Africa. He was

employed at the University of Pretoria from 2003 to 2005 where

he lectured under graduate courses in Digital Communications and

Linear System Analysis. For the last 12 years, he has been working

within the field of Radar and Electronic Warfare (EW) at the CSIR,

South Africa as a signal analyst and system engineer. His research

interest includes Radar and EW sensor systems, as well as antenna

array and signal processing (particularly in communications EW,

GNSS systems and Passive Radar).

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Presentation Outline

• Introduction

– Passive radar concept

– Achievements to date

• Seaborne Experiment

– Goals

– Land based experiment

– Sea based experiment

• Future Investigations

• Conclusion

• Acknowledgements

4

Introduction – Passive Radar Concept

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Introduction

• Current passive radar focus

– FM Broadcasting

– Starting to investigate digital TV (DVB-T2)

• Demonstrated air target detections (FM broadcasting)

– Small aircraft (Cessna) have been detected at 50km

– Large airliners detected > 300 km

• Target feature extraction

– Propeller modulation

• Sea surface vessel detections

– Namacurra

– Detections at 3 - 5km

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Introduction - FM Radio Coverage

80 km

150 km

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Introduction – Single Site Tracking

• West Coast, Western Cape, SA (2014)

– Piketberg FM transmitter

• Tracking (2-D)

– C-47TP Dakota

– Range and Angle

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Introduction – Multi-Static Tracking

• Western Cape, SA (2014)

– Cape Town FM transmitter

• Detection and tracking (2-D)

– Boeing like targets

– Off-line processing

Atlantic Rx

Kalbaskraal Rx

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Introduction – Detection Range &

Platform recognition

• Gauteng, SA (2013)

– Sentech FM Transmitter

• Target Recognition (towards)

– Accurately estimate the RPM of

a Cessna 172 propeller

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Introduction – Maritime Target Detections

• MDA Experiment in Saldanha (2014) – Transmitter (Simulated higher BW)

• 1W, FM with 2MHz IBW

• RR 75m

– Detections

• Harbour Patrol Boat (4.5km mono)

• Buoys

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Introduction – Long term passive radar test

bed development

• 5 receiver nodes

– In Gauteng Region

– Dual baselines at some Rx

• 1 central node at CSIR

– Target tracking

– Database

– Reference data interface

– Web Display

• Connected with high

bandwidth capacity links

– 1/10 Gbps South African Research Network (SANREN)

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Introduction – Preliminary results (POD, CSIR

& SANSA

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Seaborne Experiment - Research Scope

• Research Context

– Initial Investigation for using Passive Radar onboard a maritime platform

• Allow for covert operations

• Currently only air-targets are considered

– In support of Project SYNE

• Plan and Execute Trails in False Bay, Cape Town

– Test the effectiveness of FM-based passive radar on a seaborne platform (Namacurra)

– Compared to static, land-based passive radar

performance.

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Initial Experiment – AFB Waterkloof

• Equipment: (Tx - 94.2MHz)

– 1 x Ref & 1x Surv Antenna

– ComRad3 receiver (NB filter)

– IQ data recording on Laptop, offline processing

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Initial Experiment – AFB Waterkloof

• Best detection results;

– 135km detection range

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Simon’s Town Experiment

• 12th – 16th March 2018

• SAN provided Namacurra HPB

• Equipment:

– 1 x Ref & 1x Surv Antenna

– 19 Inch rack mounted PCL Rx• RF receiver (ComRad3)

• GP-GPU Processing Server

– SpatialDual IMU (dual base GNSS antenna)

– 1800W Inverter, • Using on-board batteries

– 2 x Laptops

• 3 Days IQ Data Recordings

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Simon’s Town Trials – IMU recordings

14/03/2018 15/03/2018

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Simon’s Town Experiment – Detection Results

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Simon’s Town Trials – Future

• Current Findings

– Target detections, but at limited ranges

– But, under the worst conditions (Frigate should be more stable)

• Further analysis of FM data

– Characterisation of clutter effects

– Characterisation of multipath effects

– Actual Rx position update

• Using the IMU position data

– Investigate range-Doppler migration algorithms

• For example Keystone, Chirp Z

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Simon’s Town Trials – Future

• Digital Video Broadcasting

– Higher frequency, smaller antennas

– Higher range resolution• Sea surface detections

• Drones

– Area coverage yet to be done

• Omni-directional Antennas

– Beamforming/Null steering in all directions essential

– COMINT circular array on Frigate may be well suited for this

– Dynamic range considerations

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Conclusions

• Passive radar may be able to contribute to a covert

situations awareness function in the maritime and

seaborne domain.

• It is shown that FM-based passive radar is able to detect

air targets from a small, harbour patrol vessel.

• There is significant performance degradation of classic

processing techniques due to platform motion.

• Motion compensation and circular arrays are essential to

realising a practical sensor.

• Digital television broadcasts may unlock further capability

such as sea-surface target detection.

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Acknowledgements

• Lt. Col. J. van Zyl, Lt. Col. A. van Wyk, Capt. S. Badenhorst and CO. B. van

Heerden for assisting and hosting the CSIR at Air Force Base (AFB) Waterkloof for

the land based PCL trials.

• Capt. (SAN) G. Walker and Thomas Mkhaliphi for arranging the availability of the

Namacurra.

• Cdr. R. Strydom and the Naval Electromagnetic Analysis Section (NEMAS) staff

for hosting the CSIR at the SAN Naval base during the week of the sea based PCL

trials.

• Adrian Stevens for making IMT equipment available to the CSIR during the week

of the sea based PCL trials and also for being involved with the logistics of the

CSIR equipment.

• Stephen Paine for making UCT equipment available to the CSIR during the week

of the sea based PCL trials and also for participating in these trials.

• Joshua Sendall (DPSS), for developing and implementing the adaptive range-

Doppler processing techniques under the CSIR thematic passive radar

programme.

Thank you