Radar For Australia
first specially designed storm warning surveillance radar to cover the inhibited
areas of the north-eastern coast of Australia threatened by tropical cyclones
was recently despatched to Liverpool for shipment. Weighing over eight tons,
part of the equipment will be installed on a rocky spur on Saddle Mountain,
2000 ft above sea level, in North Queensland. Power and buildings have been
provided on the site, connected with the main highway by over a mile of road,
which was specially constructed at considerable cost.
Designed and manufactured by Cossor Radar & Electronics Ltd., Harlow, Essex, to a specification of the Australian Bureau of Meteorology, the radar, which has been ordered by the Australian Commonwealth Government, will warn of the approach of hurricane winds arising from cyclone formation in the Coral Sea. Such short term warning is of great value in helping to minimise hurricane damage which on occasion may occur along the coastal region of Queensland, the area of which state alone is over seven times that of the United Kingdom.
Data from the radar on Saddle Mountain will be received via a microwave radio link to the other portions of the equipment installed at Cairns Airport, seven miles away. Trees on the hills have been cleared to establish a line of sight from mountain to airport. The radar, which has a nominal range of 240 miles, will enable meteorologists to observe the positions and tracks of storm centres, including cyclones, whose characteristic cloud patterns can been seen on a plan position indicator (p.p.i.) display. Iso-echo facilities will enable the densities of clouds and precipitation to be assessed.
The radar will operate in the "S" (10cm) band and will normally be controlled remotely from Cairns Airport via a v.h.f. link. The 800kW transmitter operates at a fixed pulse repetition frequency of 300 pulses per second with a pulse width of 2 microseconds. The aerial consists of a fixed dipole mounted at the focus of an 8ft diameter dish, giving a 2.6° beamwidth. Aerial elevation is adjustable from the airport in 2° steps between 0-16°. The azimuthal rotational information from the radar scanner is converted into a series of coded pulses, which after mixing with the video and transmitter trigger information, is decoded and applied to the remote p.p.i. The Saddle Mountain installation is completed by a monitor display and an automatically operated CO2 fire prevention system.
The remote display at Cairns Airport consists of a 12in. p.p.i. which incorporates iso-echo facilities. Four display ranges are available, the maximum being 240 miles, the shortest 30 miles. Other facilities include a north marker and a reflection plotter. The latter device enables information such as markers to be superimposed on the display without introducing parallax errors. Permanent records of display data can be obtained, either as a single shots or time lapse sequences, by a magazine loaded 16mm camera.
THE RADIO CONSTRUCTOR OCT 62