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CCTV
Systems
By John W. Colley
Grill
The CCTV Expert
October
2004 Issue
View
The Grill The CCTV Expert Archives
What does it mean when a fiber modem is advertised as having
"13 db optical budget"?
The optical budget, also known as maximum attenuation, includes
the fiber connector loss of signal amplitude at the transmitter,
receiver and/or transceiver. Adding fiber connections and
bends in the fiber contributes to the fiber path, which adds
dB losses and reduces distances.
"Optical
budget" is a generic term referring to the quantitative amount
that is available. If connections, splices, and distance exceed
the optical budget problems occur at the receive site in the
way of amplitude and electronic integrity of the signal.
From
an application standpoint the relevance for example: If product
says an optical budget of 13 dB can transmit up to 3.2 miles.
A lesser spec would not travel that far. A greater spec would
travel further, provided there were not a number of splices
along the way!
My client is considering a "web-based video" application.
What are some the issues I should discuss with my client?
Our security industry is seeing many computer software developers
enter our security world. Initially many manufactures or software
developers will offer products with different approaches to
solving technical challenge. As time goes by the industry
will migrate to the best solution. This is where the Web-based
systems are now in development.
The
video information to be transmitted and received needs to
converted from analog to digital signal or starts as digital
signal. In either case the "digital packet" that is to be
transmitted needs to be zipped up to be set over any transmission
source and unzipped at the other end.
When
traveling as digital packet it needs to conform to TCP/IP
Ethernet interfaces. The signal needs to be significantly
small to travel the Internet.
What
does this mean to be client? It means the picture being viewed
can viewed on many different sources such as a standard we
browser, new technology cell phones, blackberry type units
and PDA's. Very flexible and helpful to check in on things
on you're customer site.
How
useable using the web-based type system to record and view
remotely? Is the enough detailed for court-tested replay of
the incident? The likely hood of this type of application
is poor. Why is it poor? The limitations of the broadcast
technology are limited so the picture quality remotely when
archived is limited.
How
can I improve the storage and answer my client request for
remote transmission and viewing a court-tested archive. The
answer is to provide a quality digital video recorder (DVR)
locally and loop the signals to a web-based video application.
Some
web-based manufactures are developing this real world application
for our industry. You now need to explore the options for
your client.
My customer has huge problem with light reflecting off walls,
floors, and windows. How do I factor in light reflectance
when I quote and recommend equipment?
To gauge light reflectance and the effects on the cameras
used are to do a day and night camera survey of the area with
the actual cameras to be proposed. Once you have found the
right combination of camera and lens for that application,
it should be a baseline for future quotes for that type of
light and reflectance.
View
The Grill The CCTV Expert Archives
John
W. Colley is president of Integrated Security Systems, Ltd.
and has been in the security industry for over 25 years, beginning
his experience in the CCTV segment of security and gaining
knowledge through field experience, manufacturer training
and designing systems to meet customer needs. Colley started
his security integration firm 18 years ago, providing design,
engineering, installation and service to commercial accounts
using integrated systems. Send your CCTV/Surveillance questions
to jwc@securityiss.com.
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