SATELLINE-2ASxE
User Guide, Version 2.0
37
10.2 Radio field strength
Radio signal strength must be good enough for successful data transfer. Where field strength is
above a certain level the operational results are very good. Below this level, a few dB marginal area
occurs in which errors begin to be generated by noise and interference which will eventually lead to
loss of connection.
The field strength is at its optimum level in open space, although it will still be reduced by increasing
distance. It must also be remembered that one open space has different environmental and external
factors to another, and that the effects on transmission quality must be taken into account when
planning the system.
Ground, ground contours and buildings cause attenuation (loss of energy through absorption) and
reflection of radio waves. Buildings reflect radio waves and therefore the affects of attenuation are
not as acute when transmission is over a short distance.
However, the reflected waves will often be a bit delayed, and when they combine with the direct
radio waves they interact in either a weakening or a strengthening way. This causes the fading effect
in mobile systems. In reality very sharp signal drops spaced about 35 cm apart may occur. The
attenuation may even reach 40 dB, normally less.
