Communication on a beam of light

Free space optics (FSO) can be described as an unregulated light spectrum medium communi-cations system to communicate between buildings, using light that is not visible to the naked eye,” says Netshield director Inus Dreckmeyr.

This form of wireless technology could well become a sought-after alternative for the telecommunications industry.

FSO is a line-of-sight technology that uses lasers to provide optical bandwidth connections that can send and receive voice, video and data information on invisible beams of light.

This means that information is transmitted by light beams through the atmosphere for commercial purposes.

Moreover, the technology is now developed locally by Netshield, a company that focuses on local product development and manufacturing of electronic communication equipment.

The company is 31%-owned by Comztek – a network distributor, which sells and services software and networking equipment.

The networking distributor saw the potential with Netshield to sell this technology locally and inter-nationally.

FSO is beneficial for the customer as it is not part of a regulated spectrum, which is regulated by Icasa in South Africa.

Moreover, it does not require any security software.

The average cost for a normal 2 MB Telkom line, which may be between 500 m and 1,5 km, is about R8 000 a month.

This locally-manufactured tech-nology is sold on a once-off basis and there are no recurring costs besides maintenance expenses.

Dreckmeyr tells Engineering News that it costs about R80 000 for 500 m of laser technology and R150 000 for 1,5 km.

This technology is suitable in situ- ations where there is expensive infra-structure obstructing the erection of technology between two businesses.

Despite the fact that fibre optics cable is the most reliable way of providing optical communications, it cannot be installed without being economically prohibitive in some cases.

This means that physical labour and expenses are involved to lay the fibre optic cable, which cannot be redeployed if the customer relocates, unlike laser technology.

FSO is thus suitable since it does not harm the environment or surrounding infrastructure, emphasises Dreck-meyr.

The technology also complies with the European eye-safety standards, he notes.

FSO technology is based on con-nectivity between optical wireless units, each consisting of an optical transceiver, with a laser transmitter and receiver to provide bidirectional capability.

Each wireless unit uses a laser to transmit light through the atmosphere to another lens receiving the inform-ation.

At this point, the receiving lens connects to a high-sensitivity receiver through optical fibre.

“Any electrostatic type of storm will thus not affect the transmission of information, as the light box is connected with fibre optics to the building,” explains Dreckmeyr.

However, a primary challenge for FSO-based communication is fog, as it can hinder the passage of light through a combination of absorption, scattering and reflection.

Fog is also capable of modifying light characteristics.

Dreckmeyr reports that the company has experienced such a case in Cape Town; however, this was resolved by increasing the output power of the box by adding another transmitter.

Laser technology is suitable for companies with multiple branches and buildings, such as banks.

It is also appropriate for the mining sector, where it is difficult to trans- mit data due to the trenches and ter-rain.

The technology can be implemented in a day, unless there are unexpected delays or certain products which are not available – in that case, implementation can take up to four weeks, explains Dreckmeyr.

FSO was initially developed in the 1960s for military and aerospace applications