I had my share of problems with them,
especially range. My house is 3 floors, I
got my transcever and reciever on the 2nd
floor. I found the motion sensors have to be
a min. of the level of the floor of the 2nd
story (I use them outside). I did improve
things somewhat, by pluging in the
transcever, and running a copper wire
wrapped around it's antenna and running it
to a eyehook in the celing.
I opened up one motion detector and found
the antenna inside, cardboard tube with fine
windings around it, small about a 1/8 of a
inch. Going to try to solder the same type
of antenna out of a am / fm radio and mount
it externally.
Seems like the motion detectors transmit in
a straight line instead of all directions.