Excellent questions, although they need to be addresses separately and then
I'll provide my input from my point of view as a CCTV vendor/installer.
- Bobb - wrote:
> 1.Why would someone choose one method over another ?
A) To keep in line with the rest of the existing cameras.
B) Customers don't know the advantages and limitations between systems.
C) They choose the cheapest system (and regret it).
> 2.With CCTV you need to run coax cable ( limit x feet) and with webcams
> you use 'xx type cable' and the limit is xx feet.
A) Webcams are usually limited to a fifeteen foot USB cable. They are very
inexpensive, easy to set up...and have terrible quality.
B) IP cameras or (ethernet networked) cameras can only be run 330 feet
before they need a repeating resource.
C) Analog (American NTSC or European PAL standard) cameras can be 400 feet
with small RG-59 cable for the clearest picture and up to 1,000 feet for a
simply usable picture. If you use thicker RG-11, you can go 800 feet for
the clearest picture and 2,400 feet for a usable picture.
> 3. If small house/condo does it matter ?
RG-59 would be fine for runs under 400 feet.
> 4. I can see that wireless would be easier to setup, but if not wired
> cameras, easy for 'bad guys' to jam the signal ?
Wireless is really when you simply can't do it any other way.
> Recording styles -
> 1. Do they both take pictures periodically and save to disk ? Or is CCTV
> constantly saving?
Regardless if its a IP or analog camera, the DVR (digital video recorder
that records onto a hard drive) can be set to sample periodically,
continuously, when an external alarm contact is actuated, or when motion is
detected in the field of view.
> 2. Recording everything vs recording just an alarm condition ( and how
> to set it ?)
Some DVRs have external alarm contact inputs
> 3. Is it legal to record audio with a store camera, or this that an
> invasion of privacy ?
Generally speaking, when the general public passes over the perimeter of
your property, they loose any right to privacy. Now if you record imagery
that takes places beyond your property line, that can potentially be an
issue. Lets take it a step further, have you ever heard of anyone being
prosecuted for video taping their kids' football game and the spectators
are included in the recording?
> 4. For the PC based stuff, how to setup " an alarm condition?" so that
> you don't have to be watching the screen and do a screen capture to save
> the picture? or accidentally overwrite it ?
When you say "PC based stuff", I'll assume you are referring to a multiport
video card that is installed in your desktop computer. I haven't seen one
with external alarm inputs, but you can use motion detection with the imagery.
> I can see that 'older versions' recorded to VHS and needed a human to
> replace the tape, but do non-vhs based systems ( writing to disk rather
> than tape) overwrite themselves every x minutes ( variable setting) ?
Most DVRs have the option to over-right or not.
> And how much disk space to allow for x hours of video ? ( I can see that
> it would depend on how many cameras/frames per second etc , but how to
> determine how much to allow)
That depends on how many frames per second you are capturing, the video
quality, number of cameras, etc. If you use motion detecting, you could
possibly have months of recording time.
> How about if NOT recording, but want to just have cameras to access your
> home via internet when desired ... need remote PC online via high-speed
> and a static IP for that ? again CCTV vs webcams - other than quality
> any reason for one over another ?
A) You can set up a video web server and view your images from anywhere.
But due to the MJPEG compression it won't be as clear as the local raw
video feed. This applies to IP as well as analog cams.
B) A 3 Mbps DSL line (with a 500 Kbps upload side) is pretty much the
minimum you can get by with.
C) Many DVRs have embedded virtual static IP applications, if not a simple
router like a Linksys (and many others) have such a service built in
(dynaip for one), or you can use your own PC based app such as
www.tzo.com.
[rant mode engaged]
Rule Number 1 - Image quality is proportional to the cost of the camera. A
$200 camera will nowhere come close to an $800 one.
Rule Number 2 - Bundled packages of four or eight identical cameras are
rarely as good as individual cameras with the proper lenses. Eight cameras
with a 6 mm lens will have limited near field of view and poor far view.
You may often need a mix of 3.5 mm and 12 mm lens cameras.
Rule #3 - Outdoor cameras without an auto-iris will do poorly at noon and
after the sun goes down.
With that said, I'd avoid IP cams as they don't have the best quality due
to the MJPEG compression. Most can run power with PoE on the ethernet
cable, but if you're going to run an ethernet cable, running a separate
power cable isn't that big of deal when you use analog cameras. My IP cams
have excellent video imagery, but they are not cheap.
IMHO....the best solution is to use a decent analog camera with an
auto-iris with an *appropriate* lens with a DVR that can convert the video
to network compatible for multipoint viewing in the home or office or
internet and still retain high quality imagery an the hard drive when
viewed with a local monitor.
You can get pretty good analog cameras with a 3.5~10 mm vari-focal lens and
auto-iris for under $300 and a DVR for under $700 with 300 Gig hard drive.
Webcams vc CCTV for security 
Linear Mode
