In this paper we describe an angle diversity optical wireless system that operates at 280Mbits/s and provides
bidirectional data transmission over a wide coverage area. The system uses commercially available components and
operates at a wavelength of 860nm. Three terminals, each using seven transmitter and receiver channels were
implemented, and the system was successfully tested in a wide range of different conditions. Implementation challenges,
design and performance are also discussed, together with future directions for this work.
When a micromechanical resonator is moving in air, resistance to motion causes damping which is proportional
to the velocity of the resonator. This results in a low quality factor and reduces the sensitivity of the
resonator and hence any sensor incorporating the resonator, to any environmental changes. In this paper,
a method for increasing the quality factor of micromechanical resonant sensors using velocity feedback is
reported. To achieve this, the feedthrough signal between drive and sense connections due to parasitic
capacitance is first cancelled in order to remove the previously unreported, undesirable effects that occur
from the combination of velocity feedback and capacitive feedthrough. Using this technique, the quality
factor of a resonator in air is increased by over two orders of magnitude.