W
Wildepad
How accurate could something like this be:
Three antennae on ten foot towers are set up about 100 yards apart.
A handheld unit, no larger than about eight inches square and an inch
or so thick, uses signals from those to determine its position within
the triangle (the unit will usually be held fairly parallel to the
ground, rarely at greater than a 45 degree angle).
Now it can't just figure out it's basic spot but also what angle it is
to a baseline -- that is, it isn't enough to say that it's 83 feet
from tower #1, 212 feet from tower #2, etc., it also has to read out
that it is 18.42 degrees to the line between towers 1 and 2.
In other words, on a map with the towers plotted, it must be possible
to determine exactly where the unit is _and_ where it is pointing.
'Absolute' accuracy is not as important as repeatable and relational
accuracy -- that is, it can read 83 feet from tower #1 when it is
actually 82.4 feet, as long as it always reads the same thing at that
point and it reads 41.5 feet from that tower when it is exactly half
as far away (when it is actually 41.2 feet away). ((Does that make
sense?))
The complete unit has to be no more than $1500, and the towers with
transmitters no more than $500 each (these do not have to be
weatherproof -- they will be taken down after each day's use -- pipe
towers whose 'feet' slip into pipes driven into the ground are
probably best).
What accuracy could be reasonably reached?
Within a yard, within a foot, within an 1/8 of an inch?
Perhaps more importantly, what accuracy in the direction it's pointing
could be reached? (i.e. if there were two such units, and you plotted
their readings on a map in a computer, could you determine whether
laser pointers attached to them will cross 250 yards outside the
triangle?)
Any constructive answers appreciated.
Three antennae on ten foot towers are set up about 100 yards apart.
A handheld unit, no larger than about eight inches square and an inch
or so thick, uses signals from those to determine its position within
the triangle (the unit will usually be held fairly parallel to the
ground, rarely at greater than a 45 degree angle).
Now it can't just figure out it's basic spot but also what angle it is
to a baseline -- that is, it isn't enough to say that it's 83 feet
from tower #1, 212 feet from tower #2, etc., it also has to read out
that it is 18.42 degrees to the line between towers 1 and 2.
In other words, on a map with the towers plotted, it must be possible
to determine exactly where the unit is _and_ where it is pointing.
'Absolute' accuracy is not as important as repeatable and relational
accuracy -- that is, it can read 83 feet from tower #1 when it is
actually 82.4 feet, as long as it always reads the same thing at that
point and it reads 41.5 feet from that tower when it is exactly half
as far away (when it is actually 41.2 feet away). ((Does that make
sense?))
The complete unit has to be no more than $1500, and the towers with
transmitters no more than $500 each (these do not have to be
weatherproof -- they will be taken down after each day's use -- pipe
towers whose 'feet' slip into pipes driven into the ground are
probably best).
What accuracy could be reasonably reached?
Within a yard, within a foot, within an 1/8 of an inch?
Perhaps more importantly, what accuracy in the direction it's pointing
could be reached? (i.e. if there were two such units, and you plotted
their readings on a map in a computer, could you determine whether
laser pointers attached to them will cross 250 yards outside the
triangle?)
Any constructive answers appreciated.