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iG5 User Manual
GPS + G G BeiDou
More satellites are better. More signals are better. Even
though the iG5 tracks GPS, GLONASS, Galileo and BeiDou
satellites, OPUS currently only uses the GPS observations. So
a great constellation like the one on the right is reduced to
the minimal constellation on the left.
A modern GNSS RTK receiver has and uses more signals at all
times than the OPUS processing tools.
Baseline Distance
OPUS processes GPS baselines from your receiver all the way
back to each individual CORS station. Typically these will be
45 KM (28 miles) to 150 KM (93 miles) baselines. In some
areas the nearest CORS station might be 250 KM distant!
RTK processes the baseline from your RTK Base to your RTK
Rover which typically will be less than 10 KM (6 miles.)
Short
baselines ‘Fix’ more easily and
have substantially less
noise.
#13 Fresnel Zone Considerations
Most GPS users think of the radio path from their receiver to
each of the satellites is like a small laser beam. This is
incorrect.
The GPS beam width is spread out in a cigar shaped area
known as the
‘
Fresnel Zone
’
.
Fresnel is pronounced with a silent-s: Frenel), named after
French physicist Monsieur Fresnel.
