Improving the quality of the aerosonde video link using a
smart antenna system

Abstract: The increasing need of airborne surveillance for meteorological,
environmental and military reconnaissance over remote areas and in harsh
conditions has led to the development of a small robotic aircraft,
the Aerosonde. Now ongoing research is focused on improving the
operational capacity including upgraded communication. This work
is a contribution to the development of a vision system suitable
for the Aerosonde. The aim is to enhance the capacity of an
existing communication channel for video transmission over short
distances by means of a smart antenna system.

Several smart antenna systems are considered and compared. Based
on hardware cost, achieved gain and system complexity we conclude
that a switched antenna system is the most suitable. An algorithm
capable of steering the receiving antenna is developed and implemented with a
DSP. The algorithm is based on analysis of active video lines and uses
correlation between adjacent pixels as a measure of image quality.
The implemented algorithm showed promising results when tested,
even though they were not unambiguous due to problems with
reflections in the testing environment. However, the results
indicate that the system should work properly in a real situation
and also that it should be possible to maintain a good image
quality with limited transmitter power.