From radio astronomy to wireless communication


A CSIRO invention lies at the heart of the wireless networks that are now the
most popular way to connect computers without wires. The technology came out
of CSIRO's pioneering work in radio astronomy. This article provides a background
to this technology.

Modern wireless communication between devices, such as between a laptop and
an internet connection, involve the use of radio waves of around a few gigahertz
in frequency. But radio waves of these frequencies bounce off the walls, floor,
ceiling and furniture within a room, creating multiple pathways between the
transmitting device and the receiver.

By the early 1990s, CSIRO overcame the problems caused by these multiple pathways,
using techniques that had their origins in radio astronomy.

One key technique was the Fast Fourier Transform or FFT. The FFT is a mathematical
procedure that can be used to allow signals to be divided up, transmitted and
then recombined in a way that mostly eliminates the problem of complex reflections.

CSIRO’s expertise with FFTs evolved during the mid 1980s, when it developed
a chip specifically to do Fast Fourier Transforms.

The FFT is a procedure widely used in signal processing, with applications in
medicine, industry and consumer electronics, and the FFT chip was foreseen as
being used in those areas. But the impetus to create the chip came from radio
astronomy — and involved a group of researchers from the signal processing
group in CSIRO's then Radiophysics Division.

At the time, CSIRO was developing its Australia Telescope radio telescope, and
the signal processing group not only created the FFT chip but also contributed
to the Australia Telescope’s design.

One of the CSIRO team, Dr John O’Sullivan, had worked at the Netherlands
Foundation for Radio Astronomy (now ASTRON). There he had been part of a group
of researchers searching for short-period (nanosecond) pulses of radio waves
from exploding black holes.

The technology of the day did not allow nanosecond pulses to be recorded directly,
so Dr O’Sullivan used film as the recording medium and performed optical
Fourier transforms on the images. The technique was cumbersome and frustrating.
It was this experience that spurred the team to develop a faster, cheaper method
— the FFT chip.

For further information on CSIRO’s wireless invention, its development
and for details on all members of the CSIRO WLAN Project Team, please visit
the CSIRO site here.