[Discuss] Home security & automation

[tmetro+blu at gmail.com (Tom Metro)]

Matt Shields wrote:
> This started with me waiting for FedEx to show up with my delivery of the
> iPhone 6. The problem is if I'm working with headphones on in my office I
> can't hear the doorbell or a knock on the door...

Try one of these:
http://www.harborfreight.com/wireless-driveway-alert-system-93068.html

It's a $15 wireless motion detector with a companion receiver that
sounds a chime when triggered. (They used to promote it as a driveway
alert system, but the motion detector doesn't handle the normal thermal
variations that occur outside and triggers a lot of false alarms. Works
reliably indoors. Probably OK on a covered porch.)

The receiver has a light on it, so you'll notice it even if you have
headphones on.


> ...I can buy a multi-camera and dvr setup from BJ's for a few hundred bucks.

The multi-camera DVR setups seem appealing:

-They're integrated, turn-key.
-You usually get a bunch of cameras, and thus good coverage, for fairly
cheap.

However:

-They use analog cameras. That means you have to run coax, which is
thicker and more expensive than CAT5, to each camera. Sometimes separate
power wiring. And you're limited to NTSC resolution.
-You may be locked-in to one vendor's camera product line.
-Expansion will be limited. DVRs usually handle 4 or 8 cameras.
-The DVR boxes are just appliances running Linux, but the vendors have
been notorious for violating GPL and not supplying source. They've also
traditionally done stupid things like making the UI only work on IE
because they depend on a proprietary ActiveX control. (Hopefully they
aren't still doing that on current system.)

If you put together your own setup using IP cameras, you can start with
one camera and add as needed. Use higher resolution cameras. Use PoE to
send power and networking over the same wire. Select cameras that are
optimal for the location. And customize the server used to monitor the
cameras.

A big downside is that many low-cost IP cameras have poor reliability.
Again they often run Linux, but they're loaded up with buggy features,
on the assumption that home owners will be using them as stand-alone
devices that need to be able to handle pushing to FTP servers, sending
email, dynamic DNS, etc. They also try and include software motion
detection in them, but they do a lousy job of it. You're better off
either doing that on your server, or pairing the camera with a hardware
IR motion detector. (Some cameras integrate PIR sensors, and some have
screw terminals to attach an external sensor.)

(To me, the holey grail in IP cameras would be a low cost camera running
a simple real-time embedded operating system that only has enough
functionality to digitize, compress, and stream the video. Plus, a
hardware watchdog that automatically resets the camera if its software
crashes.)

 -Tom

-- 
Tom Metro
The Perl Shop, Newton, MA, USA
"Predictable On-demand Perl Consulting."
http://www.theperlshop.com/