The demo allows participants to see a real-time image of themselves
and the room taken by a mm-wave radar. After identifying themselves
and the objects in the room they will notice the mirror reflection
effects. The radar can also be set to the ''Marauder's map' game it
record the images of the children as they walk about - showing their
footsteps along their path. It is also possible to spell out letters
and simple pictures by moving in a pattern.
SAFIRE uses a computer to both control and record the radar signals.
The computer puts a pattern on the radar signal which is then amplified
and split into two copies
first copy of the radar signal passes up through the feedhorn, and
out through the lens into the air forming a radar beam. The beam
reflects off the angled mirror, sweeping round the room as the mirror
rotates. If you could see the radar beam, it would look like a lighthouse
A radar echo from an object in the beam returns to the mirror,
bounces back down through the lens into the feedhorn, and is sent
to a device called a mixer. The mixer compares the echo with the
second copy of the transmit signal, giving a signal which is proportional
to the distance
The computer then records the mixer output signal measuring the
distance in 10cm steps. The computer also monitors the direction
in which the beam is pointing and colour-codes the strength of the
echo reflection to build up a picture of the room
HOW DOES RADAR WORK?