somewhere near the temporal coordinates of 12/8/01 8:40 AM, the entity known
as Brian transmitted the following from bmcewen_at_mediaone.net:
>
>> On a cursory look the programs appeared to myself to be more GIS based
>> rather than GPS (any thoughts out there???) and, in fact, the software
>
> Well, GPS generally means the coordinate system itself, the Global
> Positioning System, which to me means just plain old coordinates.
Nope. GPS is the system of satellites. I forget what the coordinate system
is called. I want to say WGS-80, but I've got all that info at work.
> Differential GPS (dGPS) is one of the more accurate ways to get your
> coordinates as you are using more satellites
Nope. dGPS doesn't use more satellites. What it does is compare your
receiver's information to that of a nearby (usually fixed at a well-known
datum) GPS receiver. You are able to get a far more accurate relative
position, as the much of the errors in the positions of the two receivers
are common -- things like the error introduced by the signals passing thru
the ionosphere, since the paths are nearly identical, the errors are too.
By differencing the positions of the two receivers, most of the errors are
subtracted away.
>
> The crop of low-precision handheld street-map-displaying units are kinda a
> combination of the 2- even though common use just calls them GPS handhelds,
> IMO a true GPS handheld is about $6,000 US, just displays cryptic
> coordinates, and is used mostly by wildlife science nerds with a big
> bankroll....
Good Lord!!! What sort of GPS receiver are you talking about?? I got my
Magellan for under $100 US on eBay over a year ago.
- Eric.
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