Earlier this morning, I went to a Home Show which is going on this weekend at a local sports arena. My wife stopped at an ADT home security booth for some information. After she told me the information such as installation fee, activation fee, monthly service fee, etc. I couldn't help but think rip off. Mind you, I have never been interested in a home security service as I feel it's not needed and we don't live in a high crime area. But I began thinking and recalling people making their own security system using the basics or a combination of several retail security systems such as cameras and alarms, and recalling someone mentioning a system which can alert them via cell phone at the rise of trouble, and all for free with no monthly service to a company. Therefore, my question is simply, what is it I would need to accomplish my own home security system?
I have a Visonic Powermax Pro system which requires no monhly fee. It'll send me SMS's and call me up in case of trouble.
It's also possible to build something like this yourself. The main unit could be a mini PC like the Asus EEE Box or similar with a GSM modem or simply a cheap cell phone. And then you need to find a way to add sensors. I'm pretty sure it can be done cheaper, but you also need to consider all the work hours needed.
I used to have pretty much homebuilt water alarm system. If a water sensor was set up, a modified Linksys WRT54GS wireless router would detect it by the use of a 1-wire interface
It would then e-mail an SMS gateway and alert me that way. When I bought the alarm system, I let it alert me through that one instead.
There are several general things to consider in designing or selecting an alarm system. Some people like the feeling of safety they get from having an alarm system "monitored" by a professional alarm company. There is merit in this and, while it's not for everyone, it's worth considering at the least. If the system was to be monitored it would need to include a control panel (brain) designed for the purpose rather than a home brew. Alternatively, the system could be made to send signals or even voice messages to one or more telephone numbers in the event of an emergency. You could also make a system that just makes noise, called a "local" alarm by the security industry. Note that none of the above is intended to argue for or against monitoring. I'm only saying these are things to give some thought.
The basic components of an alarm system are as follows:
A power source, typically a 12VDC control unit with primary power coming from a plug-in transformer and backup supplied by a battery which is continually charged by the control panel.
One or more sensors which will detect attempted entry or sense an intruder once he's inside. Common sensor types include magnetic "contacts" on doors and windows, motion detectors inside the home and glass breakage detectors. Additional sensors can detect smoke, heat, water leaks, freezing temperatures, etc., as needed.
The alarm itself, usually a siren mounted where residents and/or neighbors will be alerted. Some folks like to include a strobe light to help authorities spot the house in the event of a night-time alarm and to add to the intruder's discomfort that he's been detected.
One or more keypads to turn the system on and off and to indicate any problems.
Monitoring service or a device to send a voice message as mentioned above.
You can build some of the above hardware yourself if you enjoy that sort of thing or you can buy it online or have an alarm company install the whole shebang for you. If you're skillful with tools and inclined to DIY but don't have time to design your own control panel, consider ordering a system online. They're not all that expensive and the work isn't exactly rocket science.
Unless you have the codes and the manual it will be difficult to "take over" the system. Much easier is to replace the panel and keypads. The hard work of installing a security system is all the wires and sensors. Reuse those and the keypad wiring and you will save lots of time over trying to figure out the existing system.
I recommend looking at the Elk M1 line. They run $225 to $425 for a panel, keypad, battery, speaker, RJ31X and transformer. The price difference is in how many home automation type capabilities are included.
ELK is indeed an excellent choice. Their controllers are flexible and powerful. However, even without the codes some panels can be "taken over" by the homeowner. Since that costs almost nothing it should at least be tried before abandoning the system to the scrap heap.
There certainly is and I haven't found a commercial system that meets my specs:
based system where each node is an ATMEL micro implementing a mini-alarm.
2) Cheap Infra red beams , hundreds of them covering every passage, doorway and window. Not even a frog should get past it.
3) Will need to buy reversed engineered IR beam schematics and then build it ourselves. See
reversed engineered circuits. Any circuit can be taken and reverse engineered.
4) Each IR beam connects to an ATMEL micro node,. these nodes in turn comms back to the master RS485 controller.
5) The RS485 controller interfaces with a PC where every beam break is logged on a SQL database.
So for example if you are the only person in the house, you activate that for example the kitchen beam and patio beam can't break at the same time or within a short time of each other. The PC will track your movements throughout the house and for example know that you can't break the kitchen beam, before breaking the lounge beam.
IR beams are readily available. Good ones aren't cheap and vice versa. Why does the system need to be so tight that, "Not even a frog should get past it?" I'm not trying to dissuade you, only wish to understand your reasoning.
IR beams are simple stuff as far as the electronics goes. The hard part is making the aiming mechanism reliable.
It can be done that way but that's a lot of overhead to get what you might more easily accomplish using an ordinary, resistor supervised loop.
There are home utomation controllers on the market with most of these capabilities built in. A few mods to off the shelf hardware might be all you need. Take a look, for exampole, at the ELK-M1G controller and some of the compatible SW.
The same idea might also be used to track other, less expensive and simpler to install sensors. You might want to look at a combination of IR beams, true motion detectors, magnetic contacts and glass breakage detectors.
Take the doorway or a window frame. Install lets say 10 beams spaced
10cm from each other in a stack. But build an own customized box for example 1.5m long and 6cm wide. The IR modules are inserted manually and aligned one for one and finally the whole box is closed with that black IR let through stuff one can buy somewhere for a neat professional looking job - nobody will get through it.
The problem with PIR is that all a crook does is don a heat insulating suite and simply walks pass the sensor - it won't pickup the heat. See
for a whole discussion on integrating security with radiomodems, GPS, GPRS, DSLAM, Wi-Fi etc.
Use a laser to align the beams, it's not that hard.
The RS485 system uses a single wire to communicate with lets say 40 ATMEL nodes which in turn monitor 8 IR, PIR, window sensors. That would thus be 320 devices monitored effectively by a single
line. It reduces costs because copper is extremely expensive.
One thing that might be an issue is how you will respond when the alarm goes off (sending you a text message with as much detail as can fit) and you cannot immediately return home (e.g. whole family is with you on a trip out of state) or get someone to check the house (the last time you woke up the neighbor in the middle of the night for a tree branch blown through a window, he was very annoyed).
Some police require you to have an alarm permit before they will respond to reports based on alarms. Having a monitoring center may or may not remove this requirement. You may also have to have a permit if your alarm makes enough noise to be a nuisance.
If you are planning to have this as complete do-it-yourself job and limit the volume of your alarms to scare off burglars *inside* the house and let your cell phone monitor things, you may not care. But if you're planning on calling the police to ask them to check your house (under the right circumstances), you might.
A small frog can be smaller than a big cockroach. Or you could have flies or moths set off one of the beams. How much of an issue is the problem of false alarms?
How feasable is it to go all-out and track people all over the house? You divide the house into zones that can't be entered or exited without breaking beams that divide one zone from another. Obviously you have to provide lots of information like "beam 38 divides zone 5 and zone 6". You keep count of the number of people in each zone, (perhaps to turn off lights when everyone leaves) other than zone 0 (the street outside = the whole rest of the world).
Now, given that you've got some beams and perhaps a door sensor between zone 5 (kitchen) and zone 6 (garage), and you know (well, think) that there are 2 people and one cat in the kitchen and 2 in the garage, and you get interruptions on the beam, how easy is it to distinguish:
(1) 1 person went from the kitchen to the garage. (2) 1 person went from the garage to the kitchen. (3) 2 people went from the kitchen to the garage together. (4) 2 people went from the kitchen to the garage together. (5) 1 cat went from the kitchen to the garage. (6) 1 person carrying 1 cat (or small child) went from the kitchen to the garage. (7) 1 person and 1 cat walked from the kitchen to the garage together.
Remember, people can walk from one zone to another swinging their arms or carrying boxes or a weedwhacker. Parents sometimes carry small kids or pets. People can enter the doorway, stand there for a while, then turn around and go back where they came from.
How feasible is it to identify who went through the door, perhaps by accurate timing of the breaks, from: (1) The husband (big gut) (2) The wife (slim) (3) The kid (only 4 feet tall unless walking on stilts) (4) The cat (usually only 1 foot tall when not standing on hind legs) (5) Someone else.
False alarms are dealt with by using double beams closely spaced. The IR electronics are very cheap, somehow the alarm companies have managed to sell something they build for $2 for $50. There is no need for fancy pivot points and alignment gadgets, just clamp the IR module to a rod and align. On short distances this is very easy.
Correct, it isn't really feasible using just IR that is why I said if you are alone. Establish a perimeter exclusion zone around the house lets say on top of the walls or close to it rather, a zone that should never be breached.
Stack a line of [[InfraRedLeds]] in a vertical line on top of the perimeters of the walls at an outward sloping angle.
Stack as many beams as possible to form a shield of beams.
Stack another line of beams at a 90degree angle.
Birds breaking the beams will give a lot of false alarms which is why a shield of beams are installed orthogonally or at 90degree angles from each other. An assailant would first have to breach the sloping beams before triggering the vertically stacked beams before an alarm is generated.
Insert beams between the angled electric fencing on top of the wall.
Form a beamed cage around the wall. Should the beam be broken the [[CctvCameras]] sends an image for further inspection. See [[FarmSurveillance]]
Place a PTZ camera module in the garden. On any interruption of a beam the PTZ focuses on the area and sends a real-time image via [[GpsAndGprs]], [[MeshNetworking]], [[RadioModems]] or fixed wired network such as a [[DsLam]] to the base in India.
There are platoons of unemployed Chinese and Indians with broadband internet connections. Install a [[SerialCameras]] -
inside your car and a pan-tilt system on the roof. The pan-tilt will continually rotate 360 degrees taking pictures and storing it on the [[EmbeddedPc]] -
. Every time the door opens or if the window is broken (detected with a vibration sensor) the camera inside takes a picture. The inside picture and outside picture are transmitted in real-time to China via a [[GpsAndGprs]]-http:// tinyurl.com/5gsb2c - modem connection. This results in an extremely low bandwidth usage security measure.
The Chinese will manually inspects the picture and decides wether a hijacking or theft has taken place or not. On an alert it will FTP the pictures to
for further action. The cameras will only trigger if the door is opened or the window is broken, thus providing one with a reasonable compromise between privacy , bandwidth costs and not getting killed.
The same sort of concept can be extended to perimeter protection using [[ZoneMinder]] -
- and [[InfraRedLeds]]-
On an alert the snapshot is first sent to
10 different Indians on different PC's in India and they don't have to know about each other. Each manually inspects the image and if for example it was a cow or monkey on a farm triggering the alert they will indicate is as such. If just one person fails to reply or corroborate what the other 9 are indicating triggered an alert then the farmer will receive an MMS on his phone plus a missed call to wake him up. How would anybody get past such a system ?
I would hope such a setup can't be disabled *silently*. I didn't see anything about the communication protocols used in such a setup, but I would certainly hope that you can poll a particular address, and know whether you got an answer in addition to reading a value as an answer. You shouldn't be able to poll and apparently get an answer from a nonexistent device. If a device vanishes, set off the tamper alarm.
Workarounds also include having several devices that change state often (a "clock") scattered about the network, with a predictable maximum time between changes, so if it stops reporting, you set off the tamper alarm. If you can set bits as well as read them, cross-connect some of the settable bits with the readable ones, change the state of the settable bits occasionally and see if you can read the change back on the connected readable bits.
This is somewhat similar to a burglar locking a blindfold onto a guard from behind - he may not know where the burglar is, but he darn well knows someone hostile is present. The same applies to smashing his walkie-talkie or shooting him: if the guard doesn't answer something's wrong.
If this topology is used for the alarms as well as the sensors, I definitely agree here. I do recall some TV cop show where the strategy was to effectively blind the police by setting off all the alarms in the downtown area of a city, and a burglar could do the equivalent here.
A _single_ device wouldn't disappear if the RS-485 pair was shorted. *ALL* devices would disappear at the same time. Which, IMO/E, is an unnecessary and intolerable single point of failure. (This should clarify my previous post.)
Well, no ;-) If the network is shorted, the controller can't read or transmit anything from anywhere. All the controller knows is that it can't communicate with any node or device and when communication ceased.
Right. And if this "home made security system" is monitored (and if it is not monitored, what is its value?) one creates the potential for having the police, paramedics, neighbors, and fire department all arriving at the house simultaneously to deal with the same false (or not!) alarm.
Even an inexpensive home security system sends out separate codes to the monitoring company for fire, intrusion, medical, or other (eg water) events so that the real problem can be dealt with effectively in a timely way. If not, what's the point?
HTH ... Marc
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You have a room 50meters away from the base. In this room you want to install two PIR , window halls effect switches and IR beams for lets say 16 devices. With a normal alarm panel you would have to run 16x4 =
64 wires to this room on EOL resistor loop. Rather install a custom small ATMEL based mini-alarm that monitors each device using EOL and report back the status continually to the base via RS485.
RS485 is the physical layer, you can send any data you want over it: Open,close, temp, water etc.
The point is that you must calm down a bit :) Relax we are here to explore the issues. The links you gave me can added to
If this is a typical residential room, you could use 2-3 magnetic contacts for the windows and one motion detector. If you want to go all out, add a single acoustic glass break detector. There's no need for 16 anything.
You can send all the information you need for this applicaion over a single, EOL supervised pair per detector (plus 1 pair for power) without tearing up the woodwork.
I think the point is to design and install a useful security and home automation system. The gentleman differs with you as to the efficacy of your intended approach.
If the crook manages to get to the window and the alarm is activated when the window is open it is to late. IR beams are essential to alert you before he gets in physical contact with the window. The win contact switch would be a backup meaning somehow the intruder got past the beams. You must have multiple IR beams in a security setup. The beams are a back-up for the PIR and contact switches. See
Another entrance point would be through the roof.
InfraRedLeds modules around the rain gutters at a slight downward sloping angle. Multiple beams as close as possible must be stacked within a space of 50cm extending outward from the roof perimeter. Criminals continually try to get in through the roof. Place a SerialCameras parallel to the beams at each perimeter junction of the roof. Connect the
circuit and relay the image instantly to your base should a beam be broken.