On Sun, 28 Jul 2013 07:51:25 -0400, Pat wrote:
On Sat, 27 Jul 2013 18:38:49 -0700, Jeff Liebermann
wrote:
On Fri, 26 Jul 2013 14:41:02 -0700 (PDT),
wrote:
I have a customer who has an office with five rooms.
He would like me to install a video camera at the
front door and then be able to see who walks into
the office lobby on his computer. The individual
rooms' computers are not networked but he does
have WIFI. He says he thinks that there is a way
to put the video signal over the WIFI so that everyone
in the office with a computer who is logged on
to that WIFI will be able to see the camera signal
on their computer. Is there a way to do this?
Thanks, Lenny
The video is going to saturate the wi-fi to the point where the wi-fi
will be useless. Even one camera belching uncompressed video will do
that.
That mey be true, but he doesn't need a camera belching uncompressed
video. I use IP cameras from Panasonic (higher quality but expensive)
and Foscam (inexpensive but some firmware bugs to work around). For
the need the OP is describing, he can have the camera send one jpeg
snapshot per second so wi-fi has plenty of bandwidth even if all five
users are watching.
Well, the OP mumbled something about having 5 rooms. Presumably that
means 5 computahs monitoring the video. I don't know of any camera
that can do multicast, so the JPEG every 1 second becomes a JPG every
200 msec. 640 x 480 will suffice, but I have some cameras that are
doing 1024 x 768. Grinding the file size with:
http://www.jiscdigitalmedia.ac.uk/guide/print-size-and-file-size-calculator
the 640x480 will be about 200 KBytes or 1.6Mbits. Send 5 of those
(one per computah) over the LAN and you use 8 mbits/sec of bandwidth.
That will saturate a 10baseT connection, so presumably the office is
using 100baseT or 1000baseT. For wireless, the best you can do with
ordinary 802.11g is 25 mbits/sec thruput. Spectacular claims of
802.11n performance tend to be science fiction as I've noticed that in
the presence of interference, most office wireless lans end up
settling down to about 12 mbits/sec thruput. (Connection speed is
about twice the throughput). So for wireless, the 8 mbits/sec of
camera traffic will suck about 2/3 of the available wireless bandwidth
(because only one wi-fi transmitter can be on at a time).
And, no controller is needed.
As I mumbled, IP cameras will allow multiple connections, but if there
are more than one camera, it's rather tricky for a given PC to view
more than one camera at a time. My crystal ball sees more than one
camera as NONE of the installs that I've done every stopped at one
camera.
For that, you'll need an IP camera. CAT5 wiring, with one camera per
cable.
But CAT5 wiring is sometimes impossible to run without a major hassle.
Wi-fi will work.
I have yet to see an "impossible" cable run. Expensive, messy, and
awkward, are all common, but not impossible. One client absolutely
insisted that his landlord would have a fit if he modified his offices
in any way. I always present the landlord with a copy of the work
order and the building permit application, but that didn't seem to
help. When a tenant moves out, the wiring becomes the landlords
problem, so I want him involved. I've only been turned down once.
However, this customer kept insisting it was "impossible". When he
wasn't looking, I ran flat ethernet cable under the carpeting. He
just went on to obstruct me in other ways.
I haven't had to run anything through the sewers, drains, air plenums,
or water pipes, but if necessary, those are also possible. More
commonly, I use powerline networking (HomePlug), phone line networking
(HomePNA), or ethernet over CATV coax (MoCA). MoCA is quite fast and
reliable, but not cheap.
Hint: Don't use wi-fi for devices that don't move.
I disagree. Wire is best, but wi-fi works for hard to reach places
whether they move or not.
Think of airtime (the amount of time your trashmitter is on the air)
as being a valuable resource. With wi-fi, only one transmitter can be
belching RF at a time. Using wi-fi to connect laptops, tablets,
PDA's, smartphones, game pads, and such make sense because they need
to be used almost anywhere. However, devices that are continuously
passing traffic, like TIVO, Roku, and security cameras, are simply
wastes of airtime. Since they spew data continuously, there's no
airtime left for other users with laptops etc. Things that don't need
to be wireless, should not be connected via wireless.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558