Hello,

I have to buy an alarm for my new house. The motion detectors exist in
dual-technology (passive infrared and active detection using
microwaves) or in simple technology (infrared only).

I know these detectors are continually working, even when the alarm is
not activated (the red led blinking when you move) Do you know if the
microwaves are also enable when the alarm is not activated ?

I'm not sure that this kind of waves are good for the health, even at
low emission, when we are exposated all the year (for example, in a
living-room).

Example of detector :
http://www.thecrowgroup.com/files/support/SRX_2000A.pdf

Thx to give me your opinion.

Patrick.

Patrick A. wrote:
I know these detectors are continually working, even when the alarm is
not activated (the red led blinking when you move) Do you know if the
microwaves are also enable when the alarm is not activated ?


Andy writes:
The microwave systems are continually emitting microwave energy and
detect intruders by the disturbances they make in the emitted
fields.....
They are low power, but relatively uncontrolled in level....
Personally, I wouldn't worry about the emisions, since they will be
required to meet the emission standards for safety. But if you are
still worried, and don't believe the standards are safe enough, you
should avoid them for your own peace of mind...

The infrared sytems are passive, and detect changes in the
IR emissions of objects in the room. In other words, they are simply
receivers.... and are as safe as you could want.

Ultrasonic intrusion detectors emit sound waves and detect field
disturbances. I don't think they are dangerous, but everyone isn't
of that opinion...... One can always ask is something is safe, but
it's
hard to prove absolute safety for anything that puts out energy in
any form...... I don't worry about it, but you might......

Just an input for you from one who has worked with all three
types at one time or another.


Andy W4OAH