They can both be thin film - a point you're too thick to get!
This is a copy/paste of what I typed: " Freznel type lenses (special IR
Being "Freznel type lenses" they're obviously based on something that
existed before PIR sensors. - the more you wriggle - the more you have to be
disingenuous about what I actually said.
You're even too thick to snip what I actually said, so everyone can see
you're making it up the things I never said!
One of the PIR sensor datasheets I read described them as such, It was many
years ago that I worked for the alarm company that made the PIR alarms, I
can't remember the part number and I've no idea if I still have those old
But at least I've had actual hands on industrial experience - and not just
swinging through the trees beating my chest.
A friend of mine worked for a local company that put together custom
built electronics for a lot of different customers back in the 1980's.
One of the projects was taking off the shelf video cameras and recorders
built into a weatherproof package with a magnetic detector to video any
unauthorized vehicles visiting coal mine sites. Law enforcement was also
a customer for the item including another variation built into a fake
pole mounted power transformer to be mounted outside the home of any
sort of suspect. An anonymous unsuspicious bucket truck comes out and
mounts the setup which actually draws power from the power line so
there are no batteries. Makes you kind of wonder what sort of hidden
cameras the spooks have hidden around your town. ^_^
On Sun, Feb 10, 2013 at 10:58:52AM -0600, The Daring Dufas wrote:
Cell towers are ubiquitous in some areas; on buildings, towers, etc.
I wonder if it is possible that 'dummy' antennas could operate as
tempest monitoring stations. But otherwise, the degree of electronics
miniaturization that has occurred means that it should be possible to
manufacture spy-enabled passive components that could be relatively
easily substituted in just about anything, and remember that things
like TVs and such never really turn off.
I worry less about video surveillance than audio, but MEMS devices
will eventually advance to the point where microscopic bugs will be
able to crawl or fly into a residence and set up a fairly
comprehensive spying network. All of which is an NSA/CIA wet-dream
scenario, so they're probably working on it.
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
I buy gear from Supercircuits Inc. and there are all sorts of covert
cameras you can by from them. Good grief, the cameras in cellphones are
so tiny you would expect them to be available as components to build any
sort of surveillance system. The stuff Supercircuits sells would have
been science fiction not that many years ago. ^_^
Ian worked for an alarm company alright... sitting in front of a
monitor in a call center making cold calls trying to sell crap alarm
systems... and believed the boilerplate he read off a script.
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
Many motion sensors are for security, THEREFORE the designer purposely
takes some care to NOT relate the detection to the motion. For
example, sometimes delay detection before alarm. When I worked at a
Security Electronics firm, we used to not simply watch for a level of
signal, but look at the pattern - trying to decide whether the
intruder was an animal, like a dog, or was a person. Because, most of
where our systems were used a false positive called out the guards big
Some sensor technologies simply take time to 'decide' if there has
been an intrusion. Many on the market today are for 'courtesy' like
lighting a walkway, so immediate, or related to detection, is a real
With that said, you're going to have to get some sensors and go
'upstream' to the analog signal and look for it. IR detectors, sonic
detectors, and radar detectors offer you the best hope with sonic and
radar probably being the most appropriate for what you describedyou
want to do.
Then to transfer the signal level to intensity, use a modified dimmer
You'll still have to cut into everything, but you won't have too much
fuss and design effort to mess with.
That would appear to be a non-sequitor. And directly
contradicted by how the typical security motion sensor
works. You can stand in front of it all day as long as
you don't move. Wave your arm and it triggers.
What I was mentioning is that today, what used to be a security
function - motion sensor, has become a 'courtesy' function - turning
on walk lights for guests etc. Your description is accurate. It is
like an AC coupled response.
What I was talking about was disabling the ability of an intentional
intruder from 'testing' the sensor early. Walking the space, finding
range, sensitivity to motion, etc. IF the sensor has immediate
response, is easy. IF sensor has a delayed or weird response time, is
very difficult to correlate the activity to the sensor's response.
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