Mode of operation

Free space optics transmit the data directly through the atmosphere. Free space optics use invisible infrared light for transmitting data up to distances of max. 2 km. They offer special advantages to the user:

	High data rates presently up to 1250 Mbps full duplex;
	Universal application for voice and data connections reduces cabeling costs or expensive leased lines;
	Fast planning and short-dated realisiation of new connections, which can overcome obstacles like rivers, railroads, public places and streets without a building permit;
	No frequnecy planning necessary, only notfication needed;
	License free in nearly every country.

Integration

Depending on the application our free space optics offer different interfaces. The AirLaser family comes with a duplex SC-Connector as well as an RJ45-Connector. Because of this you can integrate these systems directly in your network by connecting them to an optical port of your hub, switch or router. Only Fast Ethernet or Gigabit Ethernet signals will be transmitted.

Laserlinks for E1 connections offer RJ45 or D-Sub 25 interfaces, providing cost-effective connection possibilities to your telephone system or base stations. The transmission is compliant to G.703 protocol.

The LaserLink STM-1 is also provided with an optical interface. It transmits for exmaple video data over STM-1. The interface for the use of multimode fiber is duplex SC.

CBL offers also LaserLinks for protocol transparent transmission. Depending on construction, data rates between 1 and 155Mbps can be coupled via optical interfaces and sent to the counterpart.

Mounting

Very important for a high availability and reliable operation of the link is a solid installation of the equipment. Further the user needs a power connection and direct line of sight between the stations. For larger distances all systems can be cascaded, if obstacles have to be overcome or the path length is very high. Under certain circumstances optical links may be installed behind windows.

Some pictures of typical installations can be found in the download area.

Availability

All systems can bridge the direct line of sight even under rain, snow or mist. Very strong fog may interrupt for example a link with 1km path length, whereas a link with 400 m is still running.

If 100 percent availability of the link is necessary, CBL recommends the use of a redundant path via ISDN or a cost effective Spread Spectrum system. CBLs AirLaser provides this solution in the AirLaser IP 100 as optional equipment. In normal operation there is the high bandwidth of the wireless optical system. In case of interruption by weather conditions the system will work with reduced bandwidth after an automatic shift. As a matter of course the system will switch back to the optical path automatically, when it's reestablished.

Very short interruptions, caused by birds crossing the infrared beam, will be recognized by the protocol. A new data exchange will follow, like it is usual when collisions occur. The user will not realize this situation.