Aerospace and Electronic Systems Magazine March 2018 - 2

In This Issue - Technically
CONCEPTUAL STUDY ON BISTATIC SHIPBORNE HIGH FREQUENCY SURFACE WAVE RADAR
Shore located high frequency surface wave radar (HFSWR) have been used to great advantage for maritime surveillance. However coastal realestate can be costly and there is significant interest in placing HFSWR system onboard vessels. Placing an HFSWR system on a ship can also
overcome the line-of-sight limitation of the conventional shipborne microwave radar. In this article, the advantages and disadvantages of different
shipborne HFSWR configurations are analyzed and compared. It is shown that the spreading sea clutter caused by transmitter/receiver platform
motion can be potentially suppressed by Space-Time Adaptive Processing (STAP), and that the Multiple-Input Multiple-Output (MIMO) mode
has more advantages and flexibilities than the Single-Input Multiple-Output (SIMO) and Multiple-Input Single-Output (MISO) modes when
deployed on vessels.

DESIGN AND IMPLEMENTATION OF A HIGH-FREQUENCY SOFTWARE-DEFINED RADAR FOR COASTAL OCEAN APPLICATIONS
This article reports on the design and implementation of a high-frequency software-defined radar (HF-SDR) developed by Northern Radar Inc.
for coastal ocean remote sensing. Advantages of SDR over classical radar technology are briefly discussed. Furthermore, the overall architecture
of the system, in terms of both hardware and software, is presented. Also, field data in the form of range-Doppler maps recently acquired from
a site in the former Naval Station Argentia in Newfoundland, Canada is provided. Finally, to establish the integrity of the data, wind direction is
extracted and compared with ground-truth measurements for the same site.

TARGET MONITORING USING SMALL-APERTURE COMPACT HIGH-FREQUENCY SURFACE WAVE RADAR
High-frequency surface wave radar (HFSWR) is the primary remote sensing instrument for continuously monitoring marine vessels over a wide
area. Compared with large-array HFSWR, HFSWR with a small aperture (compact HFSWR) requires a smaller radar site, consumes less power,
and is easier to deploy and maintain. However, compact HFSWR has low azimuth detection accuracy and low signal-to-noise ratio due to the
large beam width. This results in loss of weak targets and poor target tracking. In the present study, an integrated method of detection and tracking is proposed to monitor moving targets using compact HFSWR. The detection accuracy with a 3-channel compact HFSWR was analyzed and
compared with that of an 8-channel HFSWR. Preliminary results of target monitoring with the compact HFSWR are verified with synchronous
automatic identification system data.

EXPERIMENTAL ANALYSIS OF A HF HYBRID SKY-SURFACE WAVE RADAR
The transmitting station for a high frequency (HF) hybrid sky-surface wave radars (SSWR) is usually located in an inland area, which illuminates
the over-the-horizon region via reflection from the ionosphere, while echoes scattered from targets propagate to a receiver by a surface wave
path. The combined influences of various factors severely broaden the first-order sea clutter spectrum, which affects the detection probability of
low-velocity vessels. In this article, we first introduce the first-order sea clutter frequency and analyze its broadening characteristics. Then, the
ionospheric decontamination and some sea clutter suppression algorithms are discussed, which can reduce the effect of noise and clutter. Next we
show an experimental system and provide some analysis based on the experimental data. Results from field experiments show that the HFSSWR
can detect both cooperative and uncooperative targets effectively.

EXTRACTION OF WIND DIRECTION FROM THE HF HYBRID SKY-SURFACE WAVE RADAR SEA ECHOES
The high frequency (HF) hybrid sky-surface wave radar (SSWR) system combining the superiorities of both the high frequency surface wave
radar (HFSWR) and HF sky-wave radar becomes a new means to monitor the sea state and targets continuously. We develop an experiment to
verify the sea state sensing capability of the hybrid SSWR. The wind direction is extracted from the radar backscatter spectrum and the direction
ambiguity is eliminated by the maximum likelihood (ML) method. The results compared with the in-situ data show that the ML method is adaptable for wind extraction from the HF hybrid SSWR. Although inversion accuracy needs to be improved in the future, it is feasible to extract wind
direction from this hybrid SSWR system.

HF SURFACE WAVE RADAR FOR TSUNAMI ALERTING: FROM SYSTEM CONCEPT AND SIMULATIONS TO INTEGRATION INTO EARLY
WARNING SYSTEMS
In this article, an overview of High Frequency (HF) surface wave radar development for tsunami monitoring and alerting to support early warning
systems is presented. Special attention in the context of tsunami detection is paid to the HF radar system concept, including its features and limitations,
simulated tsunami scenarios for radar performance, and genuine tsunami observations by HF surface wave radar systems. The HF radar doesn't measure the approaching wave height of a tsunami; however, it can resolve the surface current velocity signature generated when the tsunami reaches the
shelf edge. It was shown in simulations and by real tsunami events that, under most conditions, phased-array radar systems provide a better spatial resolution and a significantly faster information update rate to perform real-time tsunami detection compared to compact direction-finding radar systems.
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IEEE A&E SYSTEMS MAGAZINE
MARCH 2018

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine March 2018