Benefits of Using Fiber Optics
The most commonly asked questions about fiber systems revolve around
"how far can a signal be transmitted?" and "how many signals can I put
on one fiber?" These questions only highlight two of the many
advantages fiber offers over conventional metallic cabling systems. The
use of wire is the most limiting part of any video or data transmission
system. In terms of video, 1000 feet is the quality limit of standard
RG-59 when transmitting a black and white picture. In truth the picture
starts to degrade at the point where the signal enters the cable. High
frequencies are attenuated more than lower frequencies and results in
the loss of picture resolution. Therefore, distance is a very important
benefit of fiber systems. It is possible to transmit a video signal 2
to 3 miles with a simple video transmission system and there is
virtually no signal degradation. American Fibertek can offer a system
to transmit a video signal up to 40 miles with no repeaters or loss of
signal clarity.
Read more...Multimode vs. Singlemode Fiber
The glass fiber used in fiber optic transmission consists of a central
core upon which the signal is carried and a surrounding cladding which
has a lower refractive index to contain the signal within the core. The
cladding in most fiber today has an outside diameter of 125 microns. In
comparison, the diameter of an average human hair is 85 microns. There
are three popular sizes currently for the core diameter, 50 micron,
62.5 micron and 8 micron. Both 50 and 62.5 micron fiber are called
multimode fiber. The 8 micron fiber is called singlemode fiber.
Read more...50μ vs. 62.5μ Multimode Fiber
The glass fiber used in fiber optic transmission consists of a central
core upon which the signal is carried and a surrounding cladding which
has a lower refractive index to contain the signal within the core. The
cladding in most fiber today has an outside diameter of 125 microns. In
comparison, the diameter of an average human hair is 85 microns.
Read more...Multimode Bandwidth
There are two major bandwidth limitations for multimode fiber, modal
bandwidth and chromatic bandwidth. Modal bandwidth refers to the
characteristic of multiple light paths passing through the core, each
having a different distance to travel through the fiber depending upon
the angle that the light mode enters the fiber core.
Read more...Loss Budget
The Fiber Optic Transmission System is made up of three components:
- Transmitters
- Receivers
- The Interconnect
Read more...System Loss Budget Example
To calculate a system loss budget let’s use the following example:
Read more...Loss Budget Spreadsheets
The following links will open Excel spreadsheets to help in calculating loss budgets.
Loss Budget Calculations in Kilometers (19KB)
Loss Budget Calculations in Miles (19KB)
Loss Budget Calculations in Feet (19KB)
Balanced and Unbalanced Audio
Input Connection
The standard audio interface on American Fibertek products is a 600
Ohms balanced configuration. A balanced audio input is directly
connected across the plus and minus inputs. The shield or earth wire is
connected to the ground terminal. To connect an unbalanced signal to
the input, the audio signal is connected to the plus input. The shield
or ground wire is connected to both the minus and the ground terminals.
In either input configuration, the input impedance is 600 Ohms.
Read more...EIA422 and EIA485 Data Signals
RS422
The electrical interface described in EIA422 (RS422) is a data
transmission standard for balanced digital signals. It allows for a
single transmitter device communicating to as many as 32 receiving
devices. This type of data signal is well suited to systems that
require that data be distributed to several points without a return
data path. Several companies offer camera telemetry controllers using
this data interface. Because there is only one transmitting device on
the network, this one may remain active at all times. There is no need
for the driver to go into a high impedance state to allow others to
"talk." This configuration using multiple drivers on the same wire pair
is exclusive to RS485 described below.
Read more...Multi Protocol Data
In order to provide a more flexible product offering, AFI has
introduced the Multi Protocol Data interface on many of our newer
products that carry data signals commonly found in the security and
surveillance markets.
Read more...
