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The process
of determining water depth from the period of the waves as they
break has been established since the 1940's. Aerial photographs
were used to map beaches under enemy control. Peacetime requirements
for an accurate knowledge of channel depth are also abundant, when
keeping estuaries open for shipping operations for example or scheduling
of dredging operations.
A Navtech 77GHz millimetre wave radar deployed on the beach.
Radar systems provide a convenient remote sensing capability. This
enables large areas of the sea surface to be imaged at shallow grazing
angles. The Navtech Millimetre wave radar has been successfully
used to map waves from a distance of 200m to close into the beach.
More recent improvements to the radar technology would allow that
distance to be extended to 800m. The recorded images can be used
to infer the channel depth closer to the shore and with much higher
resolution than lower frequency X-band radar.
A plot of one image from a sequence of raw millimetre wave radar
data. The 'o' marks the millimetre wave radar location on the beach
as shown in the photograph above.
Zoomed phase images of waves, with an X-band radar providing the
background image and the higher resolution inlay generated using
Navtech millimetre wave radar. The 'x' marks the deployment location
of the X-band radar and the 'o' marks the millimetre wave radar
location on the beach.
Nested
Radar Systems for Remote Coastal Observations (Download .pdf)
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