CHC i83 User Manual 56
It has fantastic views in all directions, unfortunately a semi-truck drives by every 20-seconds and completely obscures
the receiver’s view of the southern sky. This forces the receiver (and OPUS) to lose lock. This is a
BAD
location and will
greatly increase the RMS error estimates and drop the percentage of observations used.
Large Structures to the South
This 8-story parking garage is 40 feet to the southeast of the brass rivet in the street. The red arrow points South.
This is a
bad
location because the structure completely blocks the antenna’s view to the South and East.
Huge Trees to the South
BAD
: This site is not suitable for GPS observation because of large trees to the south:
Southern sky is fully blocked and trees obscure the view directly overhead.
We can debate:
• leaves on, leaves off
• pine needles vs. broad leaves
• length of pine needles
• size of tree-trunks
• size of branches
But trees above 10° to the East, South or West are bad and 100% canopy is really bad.
Huge Trees Overhead
Trees (with or without leaves) directly above the antenna prevent the receiver from having a clear view of the sky. Even
though this location has open water to the South, it is directly underneath large trees. Water can also be a source of
significant multipath (see the next section). This is a
BAD
location:
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