Its a special at offroute.com
I had been waiting to get my desired features at a good price. Land oriented unit but also includes basic ATONS for marine use. ( I sail occasionally) Has PC interface cable so I can use it with TOPO.
I borrowed a friend’s unit a few months ago, so I feel confident it will work for me. The upload of waypoints from National Geographic (Calif) TOPO was painless.
Best part is that its set up for a left handed person (me) to use his/her thumb on the main toggle input.
Ordered it yesterday, got it today. Paid cheap shipping but they shipped it faster so as not to get clogged un in the last minute frenzy.
brcrcwr
WAAS and WGS84 are only indirectly related. WAAS is an acronym for Wide Area Augmentation System, which is a form of Differential GPS (DGPS). DGPS is a method for improving the accuracy of GPS measurements. See http://www.edu-observatory.org/gps/dgps.html and http://gps.faa.gov/gpsbasics/index.htm for more detailed descriptions. / WGS84 (World Geodetic System 1984) is one of two map datums widely used in North America. A map datum is a mathematical model used for calculating geographic positions within a mapped region. Roughly speaking, a map datum provides a grid anchored to and measured from some agreed physical location (typically a monument) or locations. WGS84 represents one of many agreements. Positional measurements are defined with respect to the grid. Measurements can be angular (Lat/Lon) or scalar (UTM). See http://www.garmin.com/support/faqs/faq.jsp?faq=17&webPage=Main%20web% 20page or http://www.maptools.com/UsingUTM/mapdatum.html or http://www.colorado.edu/geography/gcraft/notes/datum/datum.html. / WGS84 is arguably the most widely-used datum in North American and is usually the default setting on a GPS receiver. However, the USGS 7.5′ topos maps we know and love are based on the NAD27 datum (North American Datum 1927). Early 7.5′ topos included an NAD27 UTM grid, which was discontinued for many years in response to user complaints about “clutter,” then replaced as public GPS use became common. Whether present in the source map or not, this grid can be printed on any topo produced from TOPO! map software. / I notice that many free online canyon maps use the WGS84 datum and lat/lon coordinates. I’m guessing that is because most people never change the default settings on their GPS receiver, so using NAD27 might cause confusion. However, I find that maps printed at 1:24,000 scale using the UTM grid and the NAD27 datum are MUCH easier to use in the field if you’re actually trying to plot a point measured with a GPS receiver. Note that if you’re printing maps out of TOPO!, getting the correct scale may require a “scaling” (i.e., fudge) factor. / See http://gps.faa.gov/gpsbasics/index.htm, http://www.edu- observatory.org/gps/gps.html, http://www.maptools.com/index.html for some useful info on mapping in general and GPS use in particular.
— In Yahoo Canyons Group, “bruce silliman” wrote:
> I noticed in the description that it mention WAAS. In beta from Shane’s and > Tom’s websites they mention WGS84. Knowing nothing about how these work are > these two acryonyms compatible?
bruce from bryce
From: “kiwi_outdoors” Reply-To: Yahoo Canyons Group
>To: Yahoo Canyons Group
>Subject: [from Canyons Group] Good deal on GPS GARMIN ETREX LEGEND 135$
Date: Thu, 15 Dec 2005 04:01:15 -0000
Its a special at offroute.com
I had been waiting to get my desired features at a good price.
Land oriented unit but also includes basic ATONS for marine use.
( I sail occasionally)
Has PC interface cable so I can use it with TOPO.
I borrowed a friend’s unit a few months ago, so I feel confident it
will work for me. The upload of waypoints from National Geographic
(Calif) TOPO was painless.
Best part is that its set up for a left handed person (me) to use
his/her thumb on the main toggle input.
Ordered it yesterday, got it today. Paid cheap shipping but they
shipped it faster so as not to get clogged un in the last minute
frenzy.
>
Jim Bodoh
On Fri, 2005-12-16 at 05:04 +0000, bruce silliman wrote:
> I noticed in the description that it mention WAAS. In beta from > Shane’s and > Tom’s websites they mention WGS84. Knowing nothing about how these > work are > these two acryonyms compatible?
You might want to google the terms for a better explaination….
WAAS (Wide Area Augmentation System) is used to improve the accuracy of the information your GPS displays. It consists of some ground stations that monitor the GPS signal and, since they know EXACTLY where they are, in turn broadcast a correction factor which a WAAS enabled GPS can use to correct the Lat/Long it displays.
WGS84 is a bit more difficult for me to explain. Using the satellite signals, a GPS comes up with a position in 3 dimensional space, an XYZ coordinate. Unless you’re an astronaut that’s of little use to you. What you want is your position in Lat/Long and altitude. WGS84 is a system they use to convert from that XYZ coordinate to a Lat/Long and altitude on the ellipsoid we’re living on. So if Shane gives you a Lat/Long based upon a GPS that uses WGS84, you had better use one that uses it too or you could end up at a different location on our ellipsoid. I’m no GPS expert but I think any GPS you are likely to encounter right now will use WGS84.
Jim
bruce silliman
Don’t mean to rain on your parade but I just saw on buy.com the waterproof model for about the same price. Maybe you could return this one if it is the same. Cheers
I noticed in the description that it mention WAAS. In beta from Shane’s and Tom’s websites they mention WGS84. Knowing nothing about how these work are these two acryonyms compatible?
bruce from bryce
>From: “kiwi_outdoors” kiwi_outdoors@yahoo.com
Reply-To: Yahoo Canyons Group
To: Yahoo Canyons Group
Subject: [from Canyons Group] Good deal on GPS GARMIN ETREX LEGEND 135$ >Date: Thu, 15 Dec 2005 04:01:15 -0000
Its a special at offroute.com
I had been waiting to get my desired features at a good price. >Land oriented unit but also includes basic ATONS for marine use. >( I sail occasionally) >Has PC interface cable so I can use it with TOPO.
I borrowed a friend’s unit a few months ago, so I feel confident it >will work for me. The upload of waypoints from National Geographic >(Calif) TOPO was painless.
Best part is that its set up for a left handed person (me) to use >his/her thumb on the main toggle input.
Ordered it yesterday, got it today. Paid cheap shipping but they >shipped it faster so as not to get clogged un in the last minute >frenzy.
>