I am thinking of setting up a simple but effective surveillance system for my house that is:

  1. Very low powered (preferably no PCs left running out of stand-by mode)
  2. Cheap.

When motion (or sound) is detected, I would like it to:

  1. Send an email/phone alert to me
  2. Record and upload video to the web (in case they steal the camera)

So I imagine a system where I leave a netbook PC in stand-by mode and have it woken up by a motion detector. This initiates software to send alerts and periodically upload recorded video to the web.

The software part is easy for me, but I'm not really a gadget-man so I'd like some advice on using a motion sensor of some sort to wake up the PC.

Does anyone have some good advice?

I know there are a couple of questions dealing with this topic already (see here: Looking for a moderately priced home surveillance setup, and here: https://superuser.com/questions/2929/can-you-suggest-a-great-home-security-setup-anti-burglars-e-t-c) - I am seeking more specific information with this question.

4 Answers 4


(just an FYI, i authored one of the home surveillance threads you mentioned above).

The problem here is the standby requirement.

Motion detection is an algorithm run on a PC that monitors the delta between frames of video within a threshold sensitivy to "detect" motion. When the PC is in standby, nothing (and especially not the webcam) could be handling this processing.

I have tried for YEARS to come up with a good low power setup.

A few ruminations.

  1. Logitech has a prepackaged solution that does this, but requires a PC to be on. A bit pricey.

  2. Most webcams come with motion detection software that will write a frame to a directory on your disk when it detects motion. You can write a simple script to monitor that directory and send you an email with an attachment when it detects a new file. Thats been the most reliable method for me so far (at least on the cheap). I believe the labtec cameras come with such software. One thing to keep in mind, if you're watching the outdoors, it will be too bright for your average webcam (even with automatic gain control). Buy a couple of cheap camera polarizer filters from ebay, and tape/strap/ziptie the in front of the camera. This will keep your images from being overexposed (read: completely white from too much sunlight)

As far as power requirements, I ran an application called RightMark that will underclock and undervolt your processor when it detects low usage. This helped quite a bit to lower my power usage. If you're using a netbook however, i don't imagine it would use much power at all even if you left it on 24/7. Probably a few dollars worth per month.

  1. you can go all out and buy wifi or POE (power over ethernet) cameras and have them all feed Ispy (an open source webcam security package) and have that orchestrate your entire security detail. This is what i'm working on next and i will update this thread when i'm successful.

While this isn’t a technological solution (and because you're not a gadget person), have you considered a dog? You can get them from the animal shelter inexpensively. There are "maintenance" costs, but you'll get some meaningful companionship in return. You'll also provide a home for a dog that needs one. Just something to consider...

  • 2
    Yes dogs are awesome, but until they invent a talking dog I would like something that can provide the police with a description of the intruders.
    – cbp
    Commented Jul 26, 2009 at 23:19
  • 1
    Heck, i'd settle for a dog that could text-message or send email!
    – NoCarrier
    Commented Jul 31, 2009 at 23:30
  • 1
    A dog was the answer to a prior question with a similar context ( see streamreader.org/superuser/questions/2929/… ) Commented Sep 7, 2011 at 2:31

Infrared motion detectors are cheap and widely available for $10 or less. You can probably find one pretty easily with adjustable sensitivity that controls a switched device of some kind. Just hook those wires into anything that can activate your computer. You can configure your software to activate whenever the computer wakes up, check the webcam for motion, and take whatever action you're imagining.

Here's one short guide I found on tapping into the electromechanical relay on a cheap motion detector: Motion Sensor Switched Output Hack. You could also construct a simple circuit from a more barebones IR sensor, but it might not be worth the effort when the relay ones are so cheap.

If your motion sensor already has a relay on it then even a software guy such as yourself on shouldn't have trouble connecting it to your PC; it will function just like a switch. I've wired things directly into my computer's power switch before, but in this case it would make a whole lot more sense to attach it to a spare keyboard controller. Your netbook should be able to wake on a keypress, and you could easily monitor the signal from your program.

Though I do agree with NoCarrier's thought that the netbook's power consumption could be so low that if this sounds like a hassle then you might as well just leave it on.


Smart-Alec answer first.... Lowest power home surveillance system "your eyeballs looking out the window"

However you might approve of this... link text

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