|
|
The Barrier
(an entry control system)
|
|
This is a picture of a barrier, which is used
to control the number of cars entering a school. The teachers at the school are
all issued with a swipe card, which has a magnetic strip. To park in the school
car park, they have to run their card through a “magnetic stripe reader”
(below):
|
|
The magnetic stripe reader detects whether or
not the card is valid. If it is, the barrier will open. When the teachers leave
the school, the barrier will open automatically because it can “sense” when
a car is approaching the barrier. The barrier also contains a small
microprocessor, which counts the number of cards being used. Therefore, it can
alert the school if anyone is using a fake card.
|
|
Questions for you to answer:
1. What is the purpose of the barrier (hint: it might have more than one purpose)?
2.
What do you think makes the barrier open automatically when a car leaves the
school.
3. The barrier cost about £10,000 to purchase
and install. Would a human being be cheaper?
4. Would a barrier be more or less reliable
than a human being?
5. What problems might the barrier cause?
6. Could you suggest a better system?
