GPS

4:17 p.m. on January 1, 2002 (EST)
(Guest)

Is there any GPS tool capable of giving weather forecasts ? I was thinking that if a computer can tell where you are in the world and if there is any weather forecast for this part of the world, it should be able to give it to you ?

9:33 p.m. on January 1, 2002 (EST)
(Guest)

a.k.a. Don M, Don Morris, Don P. Morris

Quote:


Is there any GPS tool capable of giving weather forecasts ? I was thinking that if a computer can tell where you are in the world and if there is any weather forecast for this part of the world, it should be able to give it to you ?

I don't believe that there is such a tool, but if you have a weather radio that can receive the National Weather Service broadcasts, you are getting a local forecast that is going to be pertinent. They also have an alarm function that will let you know of broadcasts of hazardous conditions - tornadoes and the like..

1:56 p.m. on January 2, 2002 (EST)
TOP 10 REVIEWER REVIEW CORPS
2,329 reviewer rep
5,272 forum posts
Ahem!

GPS = Global _Positioning_ System

Overlooking the common blunder of referring to a GPSR (GPS receiver) as a GPS, the Global Positioning System is designed for and has the function of providing information to determine your position in the region from the Earth's surface to some altitude above the surface (exact volume of applicability is classified). It does _not_ provide weather information.

Now, what may be confusing you is that there are several GPSRs that have barometers and altimeters built in. With some training, you may be able to use the information from the barometer function to gain some indication of weather changes. However, you would be better off getting an altimeter (either mechanical one like the Thommens or electronic one like Avocet, Suunto, Nike, Brunton, et al make or distribute) and learning how to make use of their much better barometer functions.

As hikerdon says, you would also be better off getting a radio capable of receiving NOAA weather broadcasts and/or aircraft weather broadcasts, at least within the US. You can get purpose-made sets, as hikerdon notes, or get a combined radio such as some pocket-sized AM-FM units, some FRS walkietalkies, some ham radio handhelds, and most aircraft and marine handhelds. The air and marine handhelds are more useful worldwide, if you understand the local language. You might also find just using the weather service of your cell-phone provider more useful. But all radio sources are limited by radio reception. The NOAA, marine, and air transmissions are limited to near line of sight, so you may not be able to get reception in mountainous areas.

By the way, before retiring, my profession was doing design for the Global Positioning System. And yes, there is other information available from the GPS - but only if you are an Authorized User (mainly military).

8:01 p.m. on January 2, 2002 (EST)
(Guest)

Hi Bill S, want info on map projection.

Is there any freeware on map projection that I can down load? No, don't want to buy any software or upgrade my GPSR. I don't know if I catch the right term. By map projection I mean given a start "coordinate" (e.g. UTM), punch in the bearing and distance, and I'll get the destination coordinate.
Happy New Year to all. :-))

10:01 p.m. on January 2, 2002 (EST)
(Guest)

a.k.a. Don M, Don Morris, Don P. Morris
Re: Ahem!

Quote:

GPS = Global _Positioning_ System

 

Quote:

Now, what may be confusing you is that there are several GPSRs that have barometers and altimeters built in. With some training, you may be able to use the information from the barometer function to gain some indication of weather changes. However, you would be better off getting an altimeter (either mechanical one like the Thommens or electronic one like Avocet, Suunto, Nike, Brunton, et al make or distribute) and learning how to make use of their much better barometer functions.

Let me ask you a question about altitude determination using a GPSR. I remember how amusing the altitude figures were during the 1990s when selective availability was in place = truly ridiculous "information" was generated. This last summer I was impressed with the accurate altitude figures I got from a very cheap GPSR (a plain vanilla Garmin eTrex). Readings were always within 30 feet and often within 10 of the noted benchmark elevations on the USFS map I was following. In my experience, this is at least as good as anythin I ever got from a traditional barometer, and it was certainly adequate for normal hiking/backpacking use. Was I lucky or is the GPS system really this good on a reasonably consistent basis?

9:41 a.m. on January 3, 2002 (EST)
(Guest)

a.k.a. Karl, urbansherpa
Re: Hi Bill S, want info on map projection.

I don't know about backcountry 'free' maps, but for anything near a road look at www.mapblast.com (I think you now have to register,free)and it'll give you the UTM, and Lat/Long coord's (top-right corner of the map)of anywhere in North America. (and most of free world)
I've found it to be very accurate used with GPS(R)
Karl

10:39 a.m. on January 3, 2002 (EST)
(Guest)

Re: Ahem!..........Slight Correction

I somewhat agree that calling a "typical" GPS hand-held unit a "GPS" is rather misleading (since a "GPS" includes not only the "user" side of the picture, but the "satellite constellation" and the "ground control" sides of the picture, too). However, calling one a "GPSR" is rather misleading as well. With all due respect, a "typical" GPS hand-held unit is really a "GPSRADL" (Global Positioning System Receiver/Antenna/Data Logger). A "typical" unit, which 99.999999% of the users on this forum will ever use, is really a GPSRADL, which has receiver, antenna, and data logger combined into one unit-housing. Now, to call a Trimble Pro XR/XRS, or a Trimble Total Station unit a "GPSR" would be rather misleading, also, since high-grade units, such as those, have the different components separated. But, to call a Trimble Pro XR/XRS GPS receiver a "GPSR" would be quite accurate, since a Trimble Pro XR/XRS receiver is just that; e.g., just a receiver, and nothing more (with just a receiver, you have a GPSR, which is not a complete and functioning GPS "end-user" unit).


Quote:

GPS = Global _Positioning_ System

Overlooking the common blunder of referring to a GPSR (GPS receiver) as a GPS, the Global Positioning System is designed for and has the function of providing information to determine your position in the region from the Earth's surface to some altitude above the surface (exact volume of applicability is classified). It does _not_ provide weather information.

Now, what may be confusing you is that there are several GPSRs that have barometers and altimeters built in. With some training, you may be able to use the information from the barometer function to gain some indication of weather changes. However, you would be better off getting an altimeter (either mechanical one like the Thommens or electronic one like Avocet, Suunto, Nike, Brunton, et al make or distribute) and learning how to make use of their much better barometer functions.

As hikerdon says, you would also be better off getting a radio capable of receiving NOAA weather broadcasts and/or aircraft weather broadcasts, at least within the US. You can get purpose-made sets, as hikerdon notes, or get a combined radio such as some pocket-sized AM-FM units, some FRS walkietalkies, some ham radio handhelds, and most aircraft and marine handhelds. The air and marine handhelds are more useful worldwide, if you understand the local language. You might also find just using the weather service of your cell-phone provider more useful. But all radio sources are limited by radio reception. The NOAA, marine, and air transmissions are limited to near line of sight, so you may not be able to get reception in mountainous areas.

By the way, before retiring, my profession was doing design for the Global Positioning System. And yes, there is other information available from the GPS - but only if you are an Authorized User (mainly military).

1:03 p.m. on January 3, 2002 (EST)
TOP 10 REVIEWER REVIEW CORPS
2,329 reviewer rep
5,272 forum posts
picky picky

Actually, the industry terminology, and terminology used in GPS200C and the other official pubs _is_ "GPSR".

1:27 p.m. on January 3, 2002 (EST)
TOP 10 REVIEWER REVIEW CORPS
2,329 reviewer rep
5,272 forum posts
altitudes

Two answers to your question, Les.

1. Yes, the system is really that good. Actually it is better, but a unit for a "non-authorized" user is limited to using C/A code (and in a couple years, the newer non-precision codes on L2 and L5). In my experience with pocket units (in teaching land nav classes to various groups), 15-20 feet in altitude is more common when at USGS sites where their altitude accuracy is specified (look on the USGS and NGS websites for the monuments for which they specify an accuracy).

2. (a bit more pedantic answer) It's mostly perception. A few years back, when Selective Availability was operative and set to 95 percent 100 meter level, people got very perturbed at finding their horizontal position off by 40 or 50 meters, but most people accepted that. After all, if you are within a football field of your waypoint, you can generally find it, unless you are in a whiteout or dense thicket. Vertical accuracy is around 1.5 times horizontal, dependent somewhat on geometry and some other problems, which meant that the old 95 percent vertical accuracy was 150 meters. The reason vertical accuracy is worse than horizontal is basically because you only see SVs above the horizon in the vertical dimension, but all around you in the horizontal direction. Anyway, 150 meters is almost 500 feet. Most of the time the altitude would be within 200-300 feet. But people perceive vertical distances much differently than horizontal. 200 feet horizontally is about 10-15 car lengths, or 2/3 of a football field. It's easy to walk that distance. But 200 feet vertically is 12 or 13 stories. It's a lot harder to climb 12 or 13 stories than it is to walk 2/3 of a football field. Looking at a 12 story building looks like a pretty tall building in most parts of the world, and people get pretty upset if some ham radio operator puts up a 200 foot antenna tower, even though that's only a bit more than the long dimension of many suburban lots (yeah, yeah, here in the SF Bay area our lots are postage stamp size).

Another factor in vertical perception is that many trails or slopes that people walk on are 5 or 10 degrees at most. You have to go about 2300 feet horizontally on a 5 degree slope to gain 200 feet. Many people consider a 10 degree incline on a trail to be really steep. For reference, a 5 degree ski slope is beginner range, 10 degree is intermediate ("Blue"), and a 30 degree slope is considered in the advanced range ("black diamond"). Simply put, vertical distances are perceived as being much greater than the same horizontal distance.

Under SA, your position 95 percent of the time lay in a volume 100 meters in radius horizontally by 150 meters vertically - a slightly squeezed sphere, only a bit larger in the altitude direction. Now, the 95 percent volume is about 15 meters horizontal radius and 25 meters vertically. The 50 percent numbers are half that (that is, roughly 20 feet horizontally and 30 feet vertically at present).

So yes, the system is that good. Lie on your side, and it looks even better ;=>D

1:33 p.m. on January 3, 2002 (EST)
TOP 10 REVIEWER REVIEW CORPS
2,329 reviewer rep
5,272 forum posts
Position projection.

Answer 1 - Yes. Go to Joe Mehaffey's website, do a bit of searching, and you will find links to a couple dozen programs that do this. The Canadian version of the USGS has a bunch of on-line programs, some of which do this for various coordinate systems and datums. http://joe.mehaffey.com/

Answer 2 - Your GPSR probably already does have that function in it. Look at the menus under waypoints. I have here in front of me both a Magellan and a Garmin unit, and both have a waypoint projection function. Both allow selecting a stored waypoint and projecting it at a bearing and distance, and both allow projecting from your present position. Also, many of the computerized map programs have such a function built into them (that is, the topographic map programs, not the street map programs).

3:42 p.m. on January 4, 2002 (EST)
(Guest)

Thanks for the answer (this is probably the one the most related to my original question ...). The reason of my question is that the GPS/xx?xxx!x tool that you use in the mountain is already a radio (receiving + transmitting) that sends a signal that helps being located and receives back a signal that actually tells where exactly you are. I was thinking that you could receive (easily ??) a litle bit more information like a short weather forecast for the location where you are. Is it a stupid idea ? an irealistic one ?

6:15 p.m. on January 4, 2002 (EST)
(Guest)

Remember, a typical, recreational GPS(R) only "receives" signal, it does not "transmit" signal.

 

Quote:

Thanks for the answer (this is probably the one the most related to my original question ...). The reason of my question is that the GPS/xx?xxx!x tool that you use in the mountain is already a radio (receiving + transmitting) that sends a signal that helps being located and receives back a signal that actually tells where exactly you are. I was thinking that you could receive (easily ??) a litle bit more information like a short weather forecast for the location where you are. Is it a stupid idea ? an irealistic one ?

6:18 p.m. on January 4, 2002 (EST)
(Guest)

Re: picky picky

I have to agree with you there, Bill. Looking back on some data, a lot of recreational unit manufacturers do refer to their products as "GPS receivers." More than likely because "receiving" signal from GPS satellites is a typical recreational unit's main operating function.

 

Quote:

Actually, the industry terminology, and terminology used in GPS200C and the other official pubs _is_ "GPSR".

6:28 p.m. on January 4, 2002 (EST)
(Guest)

Re: altitudes

Ya'll aware that Magellan (and probably others, though I haven't noticed, yet) has integrated WAAS into some of their higher-end recreational units? They're claiming that the WAAS enabled units will now get somewhere in the range of 3-7 meter accuracy. That's getting fairly close to standard, high-end GIS/mapping grade units! Will be interesting to see what comes next, as far as recreational units are concerned....................

 

Quote:

Two answers to your question, Les.

1. Yes, the system is really that good. Actually it is better, but a unit for a "non-authorized" user is limited to using C/A code (and in a couple years, the newer non-precision codes on L2 and L5). In my experience with pocket units (in teaching land nav classes to various groups), 15-20 feet in altitude is more common when at USGS sites where their altitude accuracy is specified (look on the USGS and NGS websites for the monuments for which they specify an accuracy).

2. (a bit more pedantic answer) It's mostly perception. A few years back, when Selective Availability was operative and set to 95 percent 100 meter level, people got very perturbed at finding their horizontal position off by 40 or 50 meters, but most people accepted that. After all, if you are within a football field of your waypoint, you can generally find it, unless you are in a whiteout or dense thicket. Vertical accuracy is around 1.5 times horizontal, dependent somewhat on geometry and some other problems, which meant that the old 95 percent vertical accuracy was 150 meters. The reason vertical accuracy is worse than horizontal is basically because you only see SVs above the horizon in the vertical dimension, but all around you in the horizontal direction. Anyway, 150 meters is almost 500 feet. Most of the time the altitude would be within 200-300 feet. But people perceive vertical distances much differently than horizontal. 200 feet horizontally is about 10-15 car lengths, or 2/3 of a football field. It's easy to walk that distance. But 200 feet vertically is 12 or 13 stories. It's a lot harder to climb 12 or 13 stories than it is to walk 2/3 of a football field. Looking at a 12 story building looks like a pretty tall building in most parts of the world, and people get pretty upset if some ham radio operator puts up a 200 foot antenna tower, even though that's only a bit more than the long dimension of many suburban lots (yeah, yeah, here in the SF Bay area our lots are postage stamp size).

Another factor in vertical perception is that many trails or slopes that people walk on are 5 or 10 degrees at most. You have to go about 2300 feet horizontally on a 5 degree slope to gain 200 feet. Many people consider a 10 degree incline on a trail to be really steep. For reference, a 5 degree ski slope is beginner range, 10 degree is intermediate ("Blue"), and a 30 degree slope is considered in the advanced range ("black diamond"). Simply put, vertical distances are perceived as being much greater than the same horizontal distance.

Under SA, your position 95 percent of the time lay in a volume 100 meters in radius horizontally by 150 meters vertically - a slightly squeezed sphere, only a bit larger in the altitude direction. Now, the 95 percent volume is about 15 meters horizontal radius and 25 meters vertically. The 50 percent numbers are half that (that is, roughly 20 feet horizontally and 30 feet vertically at present).

So yes, the system is that good. Lie on your side, and it looks even better ;=>D

1:17 p.m. on January 6, 2002 (EST)
TOP 10 REVIEWER REVIEW CORPS
2,329 reviewer rep
5,272 forum posts
WAAS

Quote:

Ya'll aware that Magellan (

ummm, I think you meant to say Garmin. Garmin was the first to put WAAS into handheld receivers, a carryover from their aviation units.

WAAS (Wide Area Augmentation Service) uses signals from 2 (at present) FAA-sponsored satellite payloads to enhance the GPS signals. The problem is that these 2 SVs are geosynchronous (24 hour period, staying roughly over the same spot on the Earth), whereas the GPS birds are 12-hour and in inclined orbits (abt 55 degrees inclination). Being geosynch, the 2 WAAS SVs are close to the equator, which means they appear far to the south for users in the 48 CONUS states. People on the coasts have a bit of difficulty locking on to them consistently because they appear so low in the sky, but people in the middle of the continent can do pretty well. The FAA was planning to put up more (mostly for aviation use), but 9-11 has put a lot of things like this on hold.

1:20 p.m. on January 6, 2002 (EST)
TOP 10 REVIEWER REVIEW CORPS
2,329 reviewer rep
5,272 forum posts
addition

and a bit of a correction -

Magellan does allow projection from any waypoint, but many of the Garmin units only allow projection from your present position. In these Garmins, mark your present position, but when the screen showing the waypoint comes up (waiting for you to either accept the default number or rename the waypoint), scroll down to the bearing and distance windows. Edit them, then save the new waypoint. It seems to work best if you edit the distance first, then the bearing.

6:25 p.m. on January 7, 2002 (EST)
(Guest)

Re: WAAS

Oh, was not aware that Garmin started putting WAAS technology in their recreational land units. Magellan definitely has though; it is available in the Map 330 model series. New units are being supplied with WAAS capability installed, and older units can be "up-graded" via Magellan website downloads.

 

Quote:

Quote:

Ya'll aware that Magellan (

ummm, I think you meant to say Garmin. Garmin was the first to put WAAS into handheld receivers, a carryover from their aviation units.

WAAS (Wide Area Augmentation Service) uses signals from 2 (at present) FAA-sponsored satellite payloads to enhance the GPS signals. The problem is that these 2 SVs are geosynchronous (24 hour period, staying roughly over the same spot on the Earth), whereas the GPS birds are 12-hour and in inclined orbits (abt 55 degrees inclination). Being geosynch, the 2 WAAS SVs are close to the equator, which means they appear far to the south for users in the 48 CONUS states. People on the coasts have a bit of difficulty locking on to them consistently because they appear so low in the sky, but people in the middle of the continent can do pretty well. The FAA was planning to put up more (mostly for aviation use), but 9-11 has put a lot of things like this on hold.

4:15 a.m. on January 8, 2002 (EST)
(Guest)

Thanks Bill

I've a Magellan 2000. Like you said, no can do for map projection, but thanks for you reply and follow up. :-))

12:51 a.m. on March 10, 2002 (EST)
(Guest)

Re: Position projection.

Quote:

Answer 1 - Yes. Go to Joe Mehaffey's website, do a bit of searching, and you will find links to a couple dozen programs that do this. The Canadian version of the USGS has a bunch of on-line programs, some of which do this for various coordinate systems and datums. http://joe.mehaffey.com/

Answer 2 - Your GPSR probably already does have that function in it. Look at the menus under waypoints. I have here in front of me both a Magellan and a Garmin unit, and both have a waypoint projection function. Both allow selecting a stored waypoint and projecting it at a bearing and distance, and both allow projecting from your present position. Also, many of the computerized map programs have such a function built into them (that is, the topographic map programs, not the street map programs).

3. I am trying top find out how 'Projecting a Wayopoint' may be used by a hunter. Would you by chance have an idea?

Thanks Dick

August 23, 2014
Quick Reply

Please sign in to reply

 
More Topics
This forum: Older: Any advice on crampons? Newer: For Sale: Schoeller Dryskin jacket
All forums: Older: Pack Choice Redux Newer: zip-in or not zip-in ?!