My Apartment Security System
by Craig Wilcox
My apartment building has a typical security system where
someone can press a button corresponding to my apartment number
from the front entrance to the building and I can then talk to
them through the security system. If I decide to allow the person
entry to the building, I can unlock the front door from my
apartment to let the person in.
However, the interface for this system from the apartment
leaves much lacking. The designers of the system chose a
telephone metaphor for the interface. On the wall in my
apartment, I have what looks like a corded telephone without
dialing buttons. When the receiver is picked up from its cradle,
a contact switch is opened which enables me to hear sound from
the microphone at the front entrance to the building. This
handset, a loud buzzer, and one contact switch are the entirety
of the interface. Since the interface itself is so simple, I will
critique it in the contexts of each task that it can be used for.
Talking to someone at the building entrance
To talk to someone at the front entrance, they must first buzz
your apartment and then you simply pick up the handset and talk.
This is actually the strength of the design because the metaphor
of answering a telephone works quite well.
Disallowing access to someone at the building entrance
After talking to the person, as described above, simply hang
up the receiver. This also follows what is logical for a
telephone conversation.
Unlocking the front door to the building
This is definitely the worst aspect of the interface. To
unlock the front door, you must first be in a talking mode as
described above. Then, you need to close the contact switch on
the receiver for about two seconds before releasing. This action
then closes a relay that unlocks the front door for about two
seconds. The problem is that this process has a fifty percent
success rate. This is because success requires both the person in
the apartment to have correct timing to unlock the door and the
person at the entrance to open the door during the two seconds
that the relay is open for the door lock. Unfortunately, there is
no feedback to the person in the apartment whether the door
unlocked or the person successfully opened the door. This can be
very frustrating for both parties.
Spying on people talking around the front door
To listen in on conversations around the front door, simply
lift the receiver and listen. I do not know if the connection is
two-way or not, since I have never tried talking during this
situation. I assume that this is not the intended use of this
device. However, it is good to be aware of when you are in front
of my apartment building.
Summary
Basically, the interface for unlocking the front door is bad
enough that I do not even use it anymore. I would rather walk
down three flights of stairs than risk the chance of losing a
pizza delivery or a visitor thinking that I do not want to
let them in. I guess that pretty well summarizes my opinion of
the interface.