Comlan Limited focuses on fibre and IP Communication & Networking, providing top quality broadcast products at cost effective prices. Fiber Optic Transmitters, Receivers,Transceivers, Repeaters, converters, modems

Audio video ASI to IP converters - encoders/decoders MPEG2 MPEG4

Costs of fibre optic cable are still very high. Usually one strand of fibre optic cable is used for a one directional signal. If the client wants to transmit more than one signal, the cost increases automatically.

We provide devices to our clients that enable bi-directional (Audio/Video) and full-duplex (Data) transmission of many different signals over one strand of fibre optic cable. To achieve this, we take advantage of WDM techniques (CDWM, DWDM). Every individual electrical signal is converted into a separate colour and then all converted signals (one complex fibre optic signal) are transmitted over one strand of the fibre optic cable (CDWM, DWDM techniques). Once the receiver gets the complex fibre optic signal, it splits it through a specific prism back to single electrical signals.

This way we can transmit various signals over one strand of the fibre optic cable such as Audio/Video signals (analogue, MPEG 2, MPEG4, DVB-ASI, SDI , HD-SDI ,SMPTE295M) and Data signals (Ethernet, Gigabit Ethernet, 10/100/1000 Ethernet , RS-232, RS-422, T1, E1).

BRIEF OVER VIEW OF FIBER OPTIC CABLE ADVANTAGES OVER COPPER:

SPEED: Fibre optic networks operate at high speeds - up into the gigabits
BANDWIDTH: large carrying capacity
DISTANCE:Signals can be transmitted further without needing to be "refreshed" or strengthened.
RESISTANCE:Greater resistance to electromagnetic noise such as radios, motors or other nearby cables.
MAINTENANCE:Fibre optic cables costs much less to maintain.

In recent years it has become apparent that fibre-optics are steadily replacing copper wire as an appropriate means of communication signal transmission. They span the long distances between local phone systems as well as providing the backbone for many network systems. Other system users include cable television services, university campuses, office buildings, industrial plants, and electric utility companies.

A fibre-optic system is similar to the copper wire system that fibre-optics is replacing. The difference is that fibre-optics use light pulses to transmit information down fibre lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a fibre-optic chain will give a better understanding of how the system works in conjunction with wire based systems.

At one end of the system is a transmitter. This is the place of origin for information coming on to fibre-optic lines. The transmitter accepts coded electronic pulse information coming from copper wire. It then processes and translates that information into equivalently coded light pulses. A light-emitting diode (LED) or an injection-laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funnelled into the fibre-optic medium where they travel down the cable. The light (near infra-red) is most often 850nm for shorter distances and 1,300nm for longer distances on Multi-mode fibre and 1300nm for single-mode fibre and 1,500nm is used for for longer distances.

Think of a fibre cable in terms of very long cardboard roll (from the inside roll of paper towel) that is coated with a mirror on the inside.
If you shine a flash light in one end you can see light come out at the far end - even if it's been bent around a corner.

Light rays move easily down the fibre-optic line because of a principle known as total internal reflection. "This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the fibre-optic strand, it is possible to transmit information down fibre lines in the form of light pulses. The core must a very clear and pure material for the light or in most cases near infra-red light (850nm, 1300nm and 1500nm).

Single Mode cable is a single stand (most applications use 2 fibers) of glass fiber with a diameter of 8.3 to 10 microns that has one mode of transmission.  Single Mode Fibre with a relatively narrow diameter, through which only one mode will propagate typically 1310 or 1550nm. Carries higher bandwidth than multi-mode fibre, but requires a light source with a narrow spectral width. Synonyms mono-mode optical fibre, single-mode fibre, single-mode optical wave guide, uni-mode fibre.

Single Modem fibre is used in many applications where data is sent at multi-frequency (WDM Wave-Division-Multiplexing) so only one cable is needed - (single-mode on one single fiber)

Single-mode fibre gives you a higher transmission rate and up to 50 times more distance than multi-mode, but it also costs more. Single-mode fibre has a much smaller core than multi-mode. The small core and single light-wave virtually eliminate any distortion that could result from overlapping light pulses, providing the least signal attenuation and the highest transmission speeds of any fibre cable type.  

Single-mode optical fiber is an optical fibre in which only the lowest order bound mode can propagate at the wavelength of interest typically 1300 to 1320nm.

Multi-Mode cable has a little bit bigger diameter, with a common diameters in the 50-to-100 micron range for the light carry component (in the US the most common size is 62.5um). Most applications in which Multi-mode fibre is used, 2 fibres are used (WDM is not normally used on multi-mode fiber).  POF is a newer plastic-based cable which promises performance similar to glass cable on very short runs, but at a lower cost.

Multimode fibre gives you high bandwidth at high speeds (10 to 100MBS - Gigabit to 275m to 2km) over medium distances. Light waves are dispersed into numerous paths, or modes, as they travel through the cable's core typically 850 or 1300nm. Typical multimode fibre core diameters are 50, 62.5, and 100 micrometers. However, in long cable runs (greater than 3000 feet [914.4 meters), multiple paths of light can cause signal distortion at the receiving end, resulting in an unclear and incomplete data transmission so designers now call for single mode fibre in new applications using Gigabit and beyond.

http://www.thorfiber.com