"VSAT’’ equipment is used for
maritime satellite communications. The modulated
signal format is most often based on the DVB-S2 or DVBS2X standard.
VSAT systems use very large and heavy aperture antennas in order to
obtain high performance. Cobham is starting to investigate the possibility to combining multiple small
maritime VSAT antennas on a ship to achieve better signal to noise ratio (C/N).
By using two antennas it is
possible to improve the performance by
up to 3dB
signal processing techniques are today used to combined signals from multiple
antennas. Examples are Equal Gain Combining [EGC] & Maximal Ratio Combining
[MRC], but these algorithms have usually been applied in different contexts.
One of the specific challenges on a ship is that the
antennas are typically placed far apart. There is accordingly a large signal
delay between the antennas. This signal delay will follow the ships movements,
'roll', ‘pitch’ and ‘yaw’.
A simple simulation model of the physical path
length difference between the satellite and the two antennas on a ship shall be
developed. An optimal way to combine the two DVB-S2
satellite signals, using signal processing algorithms, shall be described and
simulated together with the model for ship movements.
VSAT operates in the Ku or Ka microwave bands, and is based on an approx. 60-100 cm diameter reflector antenna.
I samarbejde medCobham SATCOM
Knowledge of digital signal processing and communications