CAMBRIDGE, UK, October 29, 2008.
Early tests of Cambridge Consultants’ Holographic Infill Radar technology
indicate that it can distinguish between turbine blades and other moving
targets
Wind farms have been found to confuse existing radar systems, compromising
air traffic control. This has led to a situation where around 40 wind farm
projects - with a combined capital value of approximately £12 billion and a
potential output of nearly 6 GW - are delayed because of objections from the
aviation sector, according to Cambridge Consultants.
Although the vision for the UK government's mitigation strategy - the
Aviation Plan - states that “there is no universal solution” to the issue,
tests are now indicating that Cambridge Consultants' proposed solution,
based on its Holographic Radar technology, can distinguish between wind
turbine blades and aircraft.
Tests of a prototype Holographic Radar system at Ecotricity’s 66m diameter
1.5 MW turbine at Swaffham in Norfolk, UK, have provided a proof of the
principle, with a small-scale system discriminating effectively between the
turbine and a moving target. Further tests are planned with a scaled-up
system of the same instrument and moving airborne targets, before a
full-scale system is developed for testing at the site of a large wind farm.
What is a holographic radar?
The Holographic Radar is a non-scanning, continuously tracking 3D radar that
can discriminate between turbines and aircraft based on easily observable
differences in their behaviour. Current air traffic control radars can
detect an object’s movement but can’t resolve speed very well.
Cambridge Consultants’ radar provides persistent illumination of the field
of view with sufficient RF bandwidth and return signal sampling to resolve
and measure an object’s motion at fine scale, as well as its range and
direction. This enables it to effectively discriminate turbine clutter at
the level of linear signal processing.
Gordon Oswald, creator of Holographic Radar at Cambridge Consultants and
architect of the current development explains: “Current radar systems scan
the surveillance zone, emitting a pulsed beam and detecting reflections of
moving objects. Because the sampling period is too short and the interval
between scans too long, speed - or Doppler - resolution is poor and the
Doppler spectrum is aliased, making it impossible to separate the target
from the turbine using any analytical processing technique.”
Craig Webster, Head of Cleantech at Cambridge Consultants, adds: “Put
simply, [the supplementary] Holographic Radar is able to tell the difference
between an aircraft and a wind turbine because it can see that they behave
differently. It will classify and report a radar return as a target when it
sees that it moves in a way that is impossible for a turbine.
“More importantly, when plugged into an existing radar system to provide
infill coverage, it will be able to see a target turn, circle, hover or land
while in the vicinity of a wind farm, restoring a level of certainty for an
Air Traffic Controller that neither scanning radar nor predictive mitigation
strategies can offer.”
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