From: Matthew Boulanger (matthewboulanger_at_mac.com)
Date: Mon Aug 11 2003 - 17:52:51 PDT
Brian-
Yes, WAAS is really not a 'final product' yet. In reality (at least in Vermont) we haven't experienced any outages or gaps in service though.
For others who don't know about it but want to learn, I suggest:
http://gpsinformation.net/exe/waas.html
For a really quick introduction to the benefits of WAAS, Garmin has a neat webpage at:
http://www.garmin.com/aboutGPS/waas.html
Really, the point I was trying to make was that the Trimble unit for sale really won't compare to modern units. For 99$, I'd much rather get a newer unit that will give me better performance. Submeter accuracy for most people is a pipe dream (unless you have a huge budget, and a sucker for a boss/accountant). A 199$ Magellan handheld unit will give most people the accuracy they need for boating, hiking, driving, etc. Couple that with a 20$ serial cable (or build your own at home!) and it connects right to the Newton. For my money, it's a much better investment.
Yes, yes, yes, I would love to have a PC card receiver to go with my military case, and get my hands on a Leica rangefinder, and really make my coworker (a recent Newton convert, and ex-marine) VERY jealous...but I can't justify it.
What I'm interested in though is a piece of software that will speak with a total station laser transit for logging points while terrain mapping. Any suggestions?
For more info on GPS, data-logging, and the Newton, I recommend Nick Ryan's review of Fieldworker at:
http://intarch.ac.uk/journal/issue3/reviews/ryan.html
Also, for those using Fieldworker and ArcView (not sure if there is anyone else out there), you can use a quick little extension to import your data. Can be found at :
http://www.stchome.com/software/gis/default.asp
Eventually I hope to do up a website to describe what I'm up to, and the research I'm doing...but time is precious, and I'm in front of the computer all day as it is!
-Matt
BTW, Brian, what exactly do you do?
Re: [NTLK] GPS (WAS) newtontalk Digest V3 #422
>Date: Mon, 11 Aug 2003 05:20:07 -0400
>From: Brian <bmcewen_at_comcast.net>
>Subject: Re: [NTLK] GPS (WAS) newtontalk Digest V3 #422
>
>>Today, there is a new correctional system in development called WAAS (EGNOS=
> >in Europe, and a few other things in Japan, and Asia). The use of WAAS al=
>>lows you to get even further refined readings while operating, on the order=
> >of 3-5 meters. As such, most handheld GPS units are taking advantage of t=
>
>I expect Matt knows this, but for everyone else: WAAS, since in
>development, can't be trusted to be present- they turn it off and on.
>Somewhere on the FAA web pages you can find a notice of this. Plus since
>they are equatorial satellites providing the WAAS correction, ground
>reception once you are enar the latitude of the US/Canadian border the
>reception gets spotty (this isn't a problem for its intended use since the
>system is designed for airplanes a few miles up).
>
>Real time sub-meter precision and accuracy exists costs about $12k or $14k,
>depending on the model (see Trimble.com, someting like 10cm and sub-minute
>acquisition times supposedly) plus $800 per year for a satellite-based
>commercial correction service (which I'm sure the military workers get "for
>free" (free at least to the guy in the field with the right backpack). You
>can apply a correctional factor yourself in the if you have lots of time on
>your hands (you have to wait until you and the other station you are basing
>your correction upon have chatted with the same group of satellites, which
>can take a while) and are within 30? miles of a dedicated (ground) base
>station- either one provided by gov't or one you placed yourself. Since
>you usually can't expect much density of gov't provided units outside the
>US (depending on your country; we work in Mexico (see Newtons Around the
>World :) where usually there is often only one base station per State), and
>45 min wait times can happen with the other method, plus if there isn't a
>free station to use for the correction, you have to buy 2 units yourself at
>$5k each (one for planting, one for walking around with), getting reliable
>sub-5m accuracy reliably is for pretty dedicated projects.
>
>I borrowed a Garmin eTrek recently, I think the cheapest thing you could
>get last year, it reported with 5m (15ft) accuracy most of the time, found
>its satellites pretty fast, and could do a HECK of a lot of stuff- perfect
>for hiking or fishing on big lakes or whatever (map the route you took,
>find your shortest path home, route you to a given waypoint, stuff like
>that). It was way cool for the cost, I was impressed. It can't do WAAS
>but WAAS might not work well where I live/hike/fish, in Michigan, since
>here we go south to get to Canada :) but units that have WAAS are only
>about $30 more. And just a touch more $ than that gives you prebuilt
>scrollable maps, etc.
>
>For comparison, an older Trimble handheld we used for teaching Arcview, (4
>or 5 years old I guess), takes a lot longer to find its satellites, and
>when plotted in the lab, could be 30-50m off from day to day, which would
>be enough to put you on the wrong street if you made a map and were driving
>by it.
>
>It would be really fun to use a PC Card GPS in the Newt, but it's likely
>older so just be aware that you might have issues sometimes. You might
>have a little more fun with a newer handheld ($100 or $150 will get you
>going) hooked to your messagepad, most handhelds have a serial port and
>NMEA is understood by GPS Map Lite. Somewhere there is a little util for
>parsing TSIP, Trimble's binary "standard" as well, search the archives for
>TSIP). Like Eric asked, off the shelf can/will give you meter accuracy,
>starting at about 5m :) or so, sometimes 3m if you get lucky with the WAAS
>reception and availability, at least at this time.
>
>Brian
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