Tried research what could find on Garmin site but w/ my slow dialup was
too painful to delve deeply.

Best I could see appears that WAAS of roughly 10-ft (3-m) is best could
hope for. This is, I presume, all any moderate/low-cost device has?

Need/desire is to layout acreages for ag purposes--haying, etc. Need
accuracy to roughly 0.1A out of typical 80 to 160A patches. Note that
1A is 16.5-ft (1 rod) by 1/2-mile for thinking purposes. Hence, if
10-ft is best I can find a corner at one end, that's 2/3-rds an acre
roughly so really need about 1-ft. One advantage is it's flat, no
trees, no other obstructions.

Anybody have any detailed knowledge of abilities of units and how well
suited would be to start in a corner of a field and mark a line at other
end 1/2-mile away parallel to hit (say) 80A out of a quarter-section
(160A). I can locate most boundaries reasonably well by existing roads,
old fence rows that are visible if know what looking for, etc., altho
there are a couple of places that have now been in grass for nearly 30
years that don't have any visible landmarks any longer between quarters
that were all farmed together and now can't find specific location of
half-mile lines as no corner posts or other landmarks remain. Field
technician from FSA (Farm Service Agency) came out w/ their high-priced
system last year and marked one of these corners for me; he brought his
Jeep Wagoneer. We got out to place the stake and probably less than
20-ft from it turned around and couldn't find it in the grass... Not
much of it is that tall, but that quarter was last year; we made over
400 large round bales off a little under 80A.

Anyway, any input appreciated...

The ag manufacturer's tractor-mount systems are 6" or so, but they're
also multi-k $$ and this function doesn't need the ancillary crop
software, etc., just waypoints...

--

dpb wrote:
Tried research what could find on Garmin site but w/ my slow dialup
was too painful to delve deeply.

Best I could see appears that WAAS of roughly 10-ft (3-m) is best
could hope for. This is, I presume, all any moderate/low-cost device
has?
Need/desire is to layout acreages for ag purposes--haying, etc. Need
accuracy to roughly 0.1A out of typical 80 to 160A patches. Note that
1A is 16.5-ft (1 rod) by 1/2-mile for thinking purposes. Hence, if
10-ft is best I can find a corner at one end, that's 2/3-rds an acre
roughly so really need about 1-ft. One advantage is it's flat, no
trees, no other obstructions.

Anybody have any detailed knowledge of abilities of units and how well
suited would be to start in a corner of a field and mark a line at
other end 1/2-mile away parallel to hit (say) 80A out of a
quarter-section (160A). I can locate most boundaries reasonably well
by existing roads, old fence rows that are visible if know what
looking for, etc., altho there are a couple of places that have now
been in grass for nearly 30 years that don't have any visible
landmarks any longer between quarters that were all farmed together
and now can't find specific location of half-mile lines as no corner
posts or other landmarks remain. Field technician from FSA (Farm
Service Agency) came out w/ their high-priced system last year and
marked one of these corners for me; he brought his Jeep Wagoneer. We
got out to place the stake and probably less than 20-ft from it
turned around and couldn't find it in the grass... Not much of it
is that tall, but that quarter was last year; we made over 400 large
round bales off a little under 80A.
Anyway, any input appreciated...

The ag manufacturer's tractor-mount systems are 6" or so, but they're
also multi-k $$ and this function doesn't need the ancillary crop
software, etc., just waypoints...

On AVERAGE, you can get a precision of ten feet. You might get down to a
couple of feet if the GPS unit can see five or six satellites. Precision is
improved by letting the unit remain stationary for up to several minutes.
With an abundance of satellites and a ten-minute equilibration, you might
get as precise as 0.1 meter or 3 inches.

The military is in the process of launching a set of satellites that will
give precision down to a minimum of ten inches.

"dpb" wrote in message
...
Tried research what could find on Garmin site but w/ my slow dialup was
too painful to delve deeply.

Best I could see appears that WAAS of roughly 10-ft (3-m) is best could
hope for. This is, I presume, all any moderate/low-cost device has?

Need/desire is to layout acreages for ag purposes--haying, etc. Need
accuracy to roughly 0.1A out of typical 80 to 160A patches. Note that 1A
is 16.5-ft (1 rod) by 1/2-mile for thinking purposes. Hence, if 10-ft is
best I can find a corner at one end, that's 2/3-rds an acre roughly so
really need about 1-ft. One advantage is it's flat, no trees, no other
obstructions.

Anybody have any detailed knowledge of abilities of units and how well
suited would be to start in a corner of a field and mark a line at other
end 1/2-mile away parallel to hit (say) 80A out of a quarter-section
(160A). I can locate most boundaries reasonably well by existing roads,
old fence rows that are visible if know what looking for, etc., altho
there are a couple of places that have now been in grass for nearly 30
years that don't have any visible landmarks any longer between quarters
that were all farmed together and now can't find specific location of
half-mile lines as no corner posts or other landmarks remain. Field
technician from FSA (Farm Service Agency) came out w/ their high-priced
system last year and marked one of these corners for me; he brought his
Jeep Wagoneer. We got out to place the stake and probably less than 20-ft
from it turned around and couldn't find it in the grass... Not much of
it is that tall, but that quarter was last year; we made over 400 large
round bales off a little under 80A.

Anyway, any input appreciated...

The ag manufacturer's tractor-mount systems are 6" or so, but they're also
multi-k $$ and this function doesn't need the ancillary crop software,
etc., just waypoints...

--


You can get better answers on the Garmin newsgroup. There was just a thread
about accuracy.
Garmin does say about 10' from what I recall and some posting did better,
others not so good. I've seen whee they use GPS systems for harvesting so
the accuracy you need must be available at some cost level.

Ed Pawlowski wrote:
....

... I've seen whee they use GPS systems for
harvesting so the accuracy you need must be available at some cost level.

Yes, the guidance systems are 2-3" but they're a $20k+ add-on.

That's not the purpose for this nor can justify that outlay for the purpose.

Since I've found some other handheld units for the ag market that are
reasonable and software more in the budget...I might just bite at $500
and try it out and then get FSA to come double-check one or two fields
to get a feel for how well it's doing...

Any other input anybody does have would be interesting...

--

On Jul 27, 7:12*pm, dpb wrote:
Ed Pawlowski wrote:

...

... I've seen whee they use GPS systems for
harvesting so the accuracy you need must be available at some cost level.

Yes, the guidance systems are 2-3" but they're a $20k+ add-on.

That's not the purpose for this nor can justify that outlay for the purpose.

Since I've found some other handheld units for the ag market that are
reasonable and software more in the budget...I might just bite at $500
and try it out and then get FSA to come double-check one or two fields
to get a feel for how well it's doing...

Any other input anybody does have would be interesting...

--

Just out of curiosity, why do you need accuracy in plot layout to a
tenth of an acre on an 80-100 acre plot? That's .1% accuracy, which
seems extreme for common agri plot sizing.

dpb wrote:

Tried research what could find on Garmin site but w/ my slow dialup was
too painful to delve deeply.

Best I could see appears that WAAS of roughly 10-ft (3-m) is best could
hope for. This is, I presume, all any moderate/low-cost device has?

Need/desire is to layout acreages for ag purposes--haying, etc. Need
accuracy to roughly 0.1A out of typical 80 to 160A patches. Note that
1A is 16.5-ft (1 rod) by 1/2-mile for thinking purposes. Hence, if
10-ft is best I can find a corner at one end, that's 2/3-rds an acre
roughly so really need about 1-ft. One advantage is it's flat, no
trees, no other obstructions.

Anybody have any detailed knowledge of abilities of units and how well
suited would be to start in a corner of a field and mark a line at other
end 1/2-mile away parallel to hit (say) 80A out of a quarter-section
(160A). I can locate most boundaries reasonably well by existing roads,
old fence rows that are visible if know what looking for, etc., altho
there are a couple of places that have now been in grass for nearly 30
years that don't have any visible landmarks any longer between quarters
that were all farmed together and now can't find specific location of
half-mile lines as no corner posts or other landmarks remain. Field
technician from FSA (Farm Service Agency) came out w/ their high-priced
system last year and marked one of these corners for me; he brought his
Jeep Wagoneer. We got out to place the stake and probably less than
20-ft from it turned around and couldn't find it in the grass... Not
much of it is that tall, but that quarter was last year; we made over
400 large round bales off a little under 80A.

Anyway, any input appreciated...

The ag manufacturer's tractor-mount systems are 6" or so, but they're
also multi-k $$ and this function doesn't need the ancillary crop
software, etc., just waypoints...

--

It seems to me that you need to first clear the grass down to levels
that don't hide vehicles, and then get your FSA buddy in to locate the
boundaries so you can place permanent and easy to locate markers. Once
you have those points located, you can pretty easily work off of them
with a large reel tape measure, or a nice laser ranger. If the markers
are not more than 200' apart you can use the inexpensive Stanley laser
ranger with it's 100' range. Moderate priced rangers go up to about 600'
range. GPS might be useable in the future with upgraded satellites, but
it probably isn't good enough now with just a handheld receiver and no
fixed correction station like the expensive units use.

wrote:
....

Just out of curiosity, why do you need accuracy in plot layout to a
tenth of an acre on an 80-100 acre plot? That's .1% accuracy, which
seems extreme for common agri plot sizing.

That's consistent w/ FSA measurements for compliance; of course, they
have their USDA-issued devices that I've no idea what cost. If there's
an overage, one can be penalized so it is advantageous to be accurate.
It didn't use to be so much an issue before the GPS-based surveys and
4-wheelers; now they monitor much more closely since have the facility
to do so as compared when they had to use the old measuring wheel or chain.

Realistically, if within about an acre would be adequate; what I was
thinking is that if, indeed, the waypoints are 10-ft off in worst case
that could be nearly 4A in the total aggregate if each side happened to
stack up wrong. And, of course, there are other fields that are full
mile in length and the 1 rod equates to 2A over the length so a few feet
can begin to add up to measurable difference fairly quickly.

--

Pete C. wrote:
....

It seems to me that you need to first clear the grass down to levels
that don't hide vehicles, ...

The point of the measurement is to lay out for haying. Clearing the
grass first rather defeats the purpose...

--

On Jul 27, 5:25*pm, dpb wrote:
Tried research what could find on Garmin site but w/ my slow dialup was
too painful to delve deeply.

Best I could see appears that WAAS of roughly 10-ft (3-m) is best could
hope for. *This is, I presume, all any moderate/low-cost device has?

Any WAAS-capable unit is going to give you horizontal accuracy of ±3m,
99% of the time. ±3m does not disclude accuracy of ±3mm, but you're
usually going to get somewhere between those 2 standards which seems
as if should be adequate for your purposes.

You could probably use MS Streets & Trips to delineate and print your
areas of concern, for no more than 40 bucks.

Just about everything you could ever want to know about gps:
http://www.navcen.uscg.gov/
-----

- gpsman

"dpb" wrote in message
...
wrote:
...

Just out of curiosity, why do you need accuracy in plot layout to a
tenth of an acre on an 80-100 acre plot? That's .1% accuracy, which
seems extreme for common agri plot sizing.

That's consistent w/ FSA measurements for compliance; of course, they have
their USDA-issued devices that I've no idea what cost. If there's an
overage, one can be penalized so it is advantageous to be accurate. It
didn't use to be so much an issue before the GPS-based surveys and
4-wheelers; now they monitor much more closely since have the facility to
do so as compared when they had to use the old measuring wheel or chain.

Realistically, if within about an acre would be adequate; what I was
thinking is that if, indeed, the waypoints are 10-ft off in worst case
that could be nearly 4A in the total aggregate if each side happened to
stack up wrong. And, of course, there are other fields that are full mile
in length and the 1 rod equates to 2A over the length so a few feet can
begin to add up to measurable difference fairly quickly.

--
If it's essentially a one-time use, consider renting a Trimble back-pack
unit for a day or so. In a recent trial here, we located rare plants --
seedlings -- that were going into the ground, for which we needed continued
historical data (e.g., seed source, growing medium, transplant success, etc.
We GPS'd 700 plants, most of which were at most 2 feet apart and came up
with a plot using Arcmap that shows each individual plant in a small area
about 30' x 30'. Now we can go back to individual plants and measure their
growth, vitality, etc. (A previous planting tried using plant tags and
small flags to identify each plant, but neighborhood youth discovered the
site, picked up the flags, and moved the plant tags around, which meant the
group lost all of its records for individual plants.)

JimR wrote:
....

If it's essentially a one-time use, consider renting a Trimble back-pack
unit for a day or so. In a recent trial here, we located rare plants --
seedlings -- that were going into the ground, for which we needed continued
historical data (e.g., seed source, growing medium, transplant success, etc.
We GPS'd 700 plants, most of which were at most 2 feet apart and came up
with a plot using Arcmap that shows each individual plant in a small area
about 30' x 30'. Now we can go back to individual plants and measure their
growth, vitality, etc. (A previous planting tried using plant tags and
small flags to identify each plant, but neighborhood youth discovered the
site, picked up the flags, and moved the plant tags around, which meant the
group lost all of its records for individual plants.)

If successful, it would be useful every hay season because we don't hay
the same areas each year.

Which Trimble unit was it? The Juno is what I was looking at I
mentioned above as reasonable for the purpose. But, in looking further
it appears it has no useful software in the base product; that seems to
be $2K start point...

Do you understand what is in the base unit vs the added software?

--

On Jul 27, 6:12*pm, dpb wrote:
Ed Pawlowski wrote:

...

... I've seen whee they use GPS systems for
harvesting so the accuracy you need must be available at some cost level.

Yes, the guidance systems are 2-3" but they're a $20k+ add-on.

That's not the purpose for this nor can justify that outlay for the purpose.

Since I've found some other handheld units for the ag market that are
reasonable and software more in the budget...I might just bite at $500
and try it out and then get FSA to come double-check one or two fields
to get a feel for how well it's doing...

Any other input anybody does have would be interesting...

--

Any chance of measuring the extreme points and then dividing it up
and double-checking those mid-points for accuracy. That giives you
less chance of an accumulating error.

dpb wrote:

The ag manufacturer's tractor-mount systems are 6" or so, but they're
also multi-k $$ and this function doesn't need the ancillary crop
software, etc., just waypoints...

--

Any chance of getting a bored, local farmer with with the fancy
guidance systems to help out?
There are some hand held laser type measuring devices available too.
I can't remember any brand names off hand. Would it be worth while to
buy a used total station on Ebay then resell it when you're done?

hr(bob) wrote:
On Jul 27, 6:12 pm, dpb wrote:
Ed Pawlowski wrote:

...

... I've seen whee they use GPS systems for
harvesting so the accuracy you need must be available at some cost level.
Yes, the guidance systems are 2-3" but they're a $20k+ add-on.

That's not the purpose for this nor can justify that outlay for the purpose.

Since I've found some other handheld units for the ag market that are
reasonable and software more in the budget...I might just bite at $500
and try it out and then get FSA to come double-check one or two fields
to get a feel for how well it's doing...

Any other input anybody does have would be interesting...

--

Any chance of measuring the extreme points and then dividing it up
and double-checking those mid-points for accuracy. That giives you
less chance of an accumulating error.

Other than the time of backtracking and extra driving thru the fields,
not really. But, time is time and fuel is fuel. Remember it's a full
half-mile minimum from one end to the other and the it's fairly slow
going as these are heavy, clumping type grasses so it's not driving up
and down a country lane. The full-mile rows take a while even in the
pick'em'up.

That's part of the difficulty in laying out w/ the wheel; it tends to be
short owing to the hummocky nature of a path thru field as compared to
an end that does abut a road or service path that can roll down (altho
they're the exception rather than the rule as there are not roads thru
most section lines).

--

Dean Hoffman wrote:
dpb wrote:

The ag manufacturer's tractor-mount systems are 6" or so, but they're
also multi-k $$ and this function doesn't need the ancillary crop
software, etc., just waypoints...

--

Any chance of getting a bored, local farmer with with the fancy
guidance systems to help out?

They're definitely not bored this time of year...

There are some hand held laser type measuring devices available too.
I can't remember any brand names off hand. Would it be worth while to
buy a used total station on Ebay then resell it when you're done?

I'll use anything enough to be worth a certain amount (just not $20k
); no handheld laser will make a 1/2-mile and there are too many places
where there are enough rises/draws can't see over that the GPS would
have the big advantage if can work out what is cost-effective.

--

On Jul 27, 7:58*pm, dpb wrote:
wrote:

...

Just out of curiosity, why do you need accuracy in plot layout to a
tenth of an acre on an 80-100 acre plot? *That's .1% accuracy, which
seems extreme for common agri plot sizing.

That's consistent w/ FSA measurements for compliance; of course, they
have their USDA-issued devices that I've no idea what cost. *If there's
an overage, one can be penalized so it is advantageous to be accurate.


It's also consistent with big govt stupidity. There is no rational
reason that any plots need to be measured to .1% accuracy for any govt
program. One percent would be more than enough. But it's what you
get when you have idiot bureaucrats making up whatever rules they feel
like.



It didn't use to be so much an issue before the GPS-based surveys and
4-wheelers; now they monitor much more closely since have the facility
to do so as compared when they had to use the old measuring wheel or chain.