Conrad_Turbo
Member
**broken link removed**
So I have an area behind my garage which is open to the alley in which I want to monitor. I am in need of something that has a very low probability of false alarms however have a very high probability of notifying me of a person in the monitored area, I know nothing is 100%. I have used motion detection in the past, however it's too prone to false alarms due to basic traffic in the alley...so I want to come up with a new solution.
Here is the info:
- area is 30' wide by about 20' deep (from the garage to the alley)
- small birds flying around in the area
- no stray trees or bushes
- environment -50 degrees C to +50 degrees C
- area ground is dirt
- area is cleared of snow in winter
- sometimes cars will be parked in this area, however I would still like the area to be monitored
I know the best alarm system is a layered alarm system, so I have been brainstorming a few ideas and thought of using:
Laser Fence (red lines) - 3 IR lasers (where can I find low cost IR laser diode?) placed 1' apart horizontally the length of the opening. Placed 3' back from the alley.
Ultrasonic Detector (green boxes) - pointing down from the garage onto the monitored area behind the lasers.
The reasoning behind the laser fence is to require each laser beam to be cut in order (#1 being the laser closest to the alley and all the way through). This would reduce false alarms due to birds, if they did manage to pass through one of the beams. Also the sensors for the lasers would adapt to the weather (due to snow or rain) since it will only count a cut beam, not degradation in signal.
The ultrasonics could be used in case if a car was parked behind the garage, cutting some or all of the laser beams, and the ultrasonic sensor could monitor the existing environment and if there is a rate of change beyond a specified value then the alarm would trip. Also if there was nothing blocking the lasers the ultrasonics could still be on to monitor the area between the lasers and the garage. In case someone slipped by or knew about the lasers (which 99% chance they won't).
All these inputs and outputs (for modulating the lasers) will be controlled via a microcontroller and the output will be sent wirelessly to the house with an "alarm box" that just highlights which zones have been tripped.
What do you guys think?
So I have an area behind my garage which is open to the alley in which I want to monitor. I am in need of something that has a very low probability of false alarms however have a very high probability of notifying me of a person in the monitored area, I know nothing is 100%. I have used motion detection in the past, however it's too prone to false alarms due to basic traffic in the alley...so I want to come up with a new solution.
Here is the info:
- area is 30' wide by about 20' deep (from the garage to the alley)
- small birds flying around in the area
- no stray trees or bushes
- environment -50 degrees C to +50 degrees C
- area ground is dirt
- area is cleared of snow in winter
- sometimes cars will be parked in this area, however I would still like the area to be monitored
I know the best alarm system is a layered alarm system, so I have been brainstorming a few ideas and thought of using:
Laser Fence (red lines) - 3 IR lasers (where can I find low cost IR laser diode?) placed 1' apart horizontally the length of the opening. Placed 3' back from the alley.
Ultrasonic Detector (green boxes) - pointing down from the garage onto the monitored area behind the lasers.
The reasoning behind the laser fence is to require each laser beam to be cut in order (#1 being the laser closest to the alley and all the way through). This would reduce false alarms due to birds, if they did manage to pass through one of the beams. Also the sensors for the lasers would adapt to the weather (due to snow or rain) since it will only count a cut beam, not degradation in signal.
The ultrasonics could be used in case if a car was parked behind the garage, cutting some or all of the laser beams, and the ultrasonic sensor could monitor the existing environment and if there is a rate of change beyond a specified value then the alarm would trip. Also if there was nothing blocking the lasers the ultrasonics could still be on to monitor the area between the lasers and the garage. In case someone slipped by or knew about the lasers (which 99% chance they won't).
All these inputs and outputs (for modulating the lasers) will be controlled via a microcontroller and the output will be sent wirelessly to the house with an "alarm box" that just highlights which zones have been tripped.
What do you guys think?