Using Ronja in restricted historical urban zones
Ronja is an optical datalink 10Mbps full duplex over 1.4km:
Installation behind a small window
Ronja is highly adaptable to installation behind a small window, because:
- The beam diameter is typically only 13cm and can be further reduced to 9cm.
- Receiver and transmitter head can be installed totally separately, separated by
- Indoor, the protective hood need not be used, which further reduces size of the
- Reflection losses on typical today's window, double pane of float glass, reduce the range only by
- Today, as opposed to 20 years ago, float glass is used instead of drawn one in windows.
Float glass doesn't present scattering loss because is extremely flat.
This night picture is from Lausanne, Switzerland. The sharp red light from Ronja you see is visible
only in the exact place of receiver, from other directions nothing is visible.
The view looks like this in daylight:
Therefore Ronja doesn't pose problem even
in historical part of Lausanne, because is not visible by public.
If even this should be a problem, infrared Ronja can be employed.
Churches and watertowers
- Multiple Ronjas can be easily installed church steeples or watertowers, where
multiple openings or windows are available. If the small amount of highly-directional
radiated red light would be a problem, infrared Ronja can be employed.
As seen in this picture from protected historical urban zone, Ronja can be concealed
low behind a chimney due to it's relaxed technical requirements:
- No Fresnel zones are required. Fresnel clearance for light is about
3cm in the middle of 1km track. Therefore, the device can be lowered up to the point where the
beam almost touches edge of the roof
- As compared to directional microwave antenna, Ronja requires only 13 centimetre wide beam to
- Adjacent metallic obstacles are of no importance, because Ronja doesn't use radio waves.
Ronja can be small
The picture shows how inconspicuous a 90mm version of Ronja (left, with reduced range of 900m) can be,
compared to a satellite dish (right).