gps to measure feet?

"Cub Driver" wrote in message
...

Sounds like something used mainly by surveyors?

In the deeds I read, surveyers measured by chains and rods. I think
they also used perches, but I have never seen a reference to one.

all the best -- Dan Ford

The ones I have seen lately use mainly lasers and detectors. I think GPS is
used in some manner, also.
--
Jim in NC


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Morgans wrote:
"Ron Natalie" wrote

There are other coordinate systems than lat/long. A state plane picks
an arbitrary place in the state and measures in feet (or meters) from
that North and East. Similarly, Universal Transverse Mercator chops up
the earth into 3 degree zones and then makes meters north and east from
a reference point in that zone.



Sounds like something used mainly by surveyors?

Not just surveyers. Most government and utility based stuff uses
state plane coordinates. It makes the math easier and more accurate
since the state plane (in some larger states there may be several)
is defined for a local area.

On Tue, 9 Nov 2004 06:54:49 -0500, "Morgans"
wrote:

In the deeds I read, surveyers measured by chains and rods. I think
they also used perches, but I have never seen a reference to one.

all the best -- Dan Ford

The ones I have seen lately use mainly lasers and detectors. I think GPS is
used in some manner, also.

I meant that the survey literally recorded measurements as "three
chains, two rods from the oak tree to the other oak tree".

(I particularly like "the other oak"

One chain = 66 feet.

One rod = 16.5 feet

(How would you like to carry that chain and rod around with you all
day?)


all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

Cub Driver wrote:
On Tue, 9 Nov 2004 06:54:49 -0500, "Morgans"
wrote:


In the deeds I read, surveyers measured by chains and rods. I think
they also used perches, but I have never seen a reference to one.

all the best -- Dan Ford


The ones I have seen lately use mainly lasers and detectors. I think GPS is
used in some manner, also.


I meant that the survey literally recorded measurements as "three
chains, two rods from the oak tree to the other oak tree".

(I particularly like "the other oak"

One chain = 66 feet.

One rod = 16.5 feet

Just how does modern surveying equipment work? One guy holds one of
those mirrors (actually a prism) that reflects light back to the source,
independent of the angle of the mirror. The instrument head contains a
laser. Distances must be measured by angles, but how?

Cub Driver wrote:

(How would you like to carry that chain and rod around with you all
day?)

That's what they have apprentices for. :-)

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.

Just how does modern surveying equipment work? One guy holds one of those
mirrors (actually a prism) that reflects light back to the source,
independent of the angle of the mirror. The instrument head contains a
laser. Distances must be measured by angles, but how?

Akshully, it is not a prism -- it is more like a corner relfector whereby
any incident energy entereing the front is reflected back toward the source.
In case of the ranging instrument using a laser. The transmitter sends out a
discrete pulse of energy and measures the time it takes for the pulse to
return to a colocated receiver. The round-trip time is divided in half then
multiplied by a constant approximating one nano-second per foot to reveal
the slant-range distance. Angles ain't needed unless the surveyor must
calculate the horizontal distance, in which case he needs the alpha-angle
and that is done with a protractor.

Cub Driver ) wrote:
:
: Does anyone know the exact conversion in feet for a minute of latitude and
: longitude?
:
: But I am scratching my head over the longitude! Doesn't a minute of
: longitude depend on your location between the pole and the equator?

You plug the latitude into the cosine function and that gives you
a factor to tell you how short the longitide is.

cos(0)=1 cos(90)=0 cos(60)=.5

So if one minute (1/60th of a degree) is one nmi at the equator,
then at poles its 1*cos(90)=0 or at 60 degrees north (or south)
its 1*cos(60)=.5

Google claims 1 nautical mile = 6 076.11549 feet so
at 60 degrees it should be about 3038 feet.

-tim
http://web.abnormal.com

On Wed, 10 Nov 2004 14:47:56 GMT, "William W. Plummer"
wrote:

Just how does modern surveying equipment work? One guy holds one of
those mirrors (actually a prism) that reflects light back to the source,
independent of the angle of the mirror. The instrument head contains a
laser. Distances must be measured by angles, but how?

Speed of light?

all the best -- Dan Ford
email: (put Cubdriver in subject line)

Warbird's Forum www.warbirdforum.com
Piper Cub Forum www.pipercubforum.com
the blog www.danford.net

On Thu, 11 Nov 2004 at 06:35:23 in message
, Tim Hogard
wrote:

Google claims 1 nautical mile = 6 076.11549 feet so

That's right it is the international nautical Mile,
which is exactly 1,852 metres

I am not sure if the UK nm still exists - that was 6080 ft. Does anyone
know how the UK came to have their own version? I assume it has
disappeared but I am not sure when it did.
--
David CL Francis

David CL Francis wrote:

I am not sure if the UK nm still exists - that was 6080 ft. Does anyone
know how the UK came to have their own version? I assume it has
disappeared but I am not sure when it did.

According to a reference I found on British measurements, the nautical mile is --
"Unit of length, normally at sea or in the air. Originally, the Admiralty fixed it at
6080 feet. This unit is universally used by international law by ships and aircraft,
as is the derived unit of the knot.
In the 20th century, an international nautical mile was defined as 1852 metres, and
so you will sometimes see the 6080ft nautical mile called the British nautical mile."

So it would seem that the international nautical mile is not used for navigation.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.