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Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Etrex 10 or Etrex H on 05/16/2012 18:51:18 MDT Print View

> Etrex 10. It's RRP$119 compared to the EtrexH RRP$99, but
> it has a 50% increase in battery life,
Good

> and is slightly lighter
Good

> It also connects up by USB, not serial,
Good (few PCs today even have a serial port!)

> They both use a high sensitivity chip
In fact, imagining that the more expensive of two *modern* GPS units might have better reception is usually just deluding yourself. The extra cost is all for the extra features.

This does NOT mean that that the chip in the current eTrex H is the same one as was found in a Garmin 10+ years ago: it isn't. They moved to a new upgraded SiRF II receiver some years ago when they introduced the H range. The new chip is much better. That made the Geckos and other models obsolete.
(if the change was 12 years ago - oh well, time flies ...)

Cheers

Herbert Sitz
(hes)

Locale: Pacific NW
Re: battery life on 05/16/2012 18:59:24 MDT Print View

M.L. -- Not sure what your battery life requirement is, but how/what are you projecting as a smartphone's battery life? Smartphones last a hell of a long time when wireless is disabled. Plus almost all Android smartphones have replaceable batteries, so you can just bring an extra. For someone using gps on only an intermittent basis I don't see how battery life could be an issue at all, you can just enable and disable gps when needed. Here's link with some info on smartphone battery life with gps: android battery life with gps.

It's important to remember that smartphones are multi-purpose and not very heavy. Most Android phones weigh 5oz or less, you can carry a spare battery or two and still come out way ahead weight-wise.

I have no knowledge of how reception compares between smartphones and dedicated receivers, but I'm sceptical of anecdotal reports.

Edited by hes on 05/16/2012 19:15:21 MDT.

bill berklich
(berklich)

Locale: Northern Mid-West
GPS, Glosnass, Galileo and Compass Constellations on 05/16/2012 20:17:45 MDT Print View

Most higher end GPS receivers are now being programed to accept any of the 4 constellations GPS (USA), Glosnass (Russian), Galileo (EU) and Compass (China). These consist of 12 to 24 sats each in LEO/MEO. Your GPS needs 3 sats to provide position and a fourth and fifth for elevation. Having access to almost 100 sats improves your accuracy and the "window" if you are deep in a canyon.

GPS location data in deep canyons is notoriously bad because of signal bounce. As a civilian GPS accuracy is deliberately degraded from the Military Standard.

Btw the US GPS Constellation is in the process of failing due to a lack of funding and a delay in technology. In 5 to 8 years we will be dependent on Glosnass, Galileo and Compass.

Hamish McHamish
(El_Canyon) - M

Locale: USA
Re: Re: etrex on 05/16/2012 20:31:59 MDT Print View

>the etrex 10 doesn't have a compass. Since it doesn't have a compass, it won't be able to > >point to a waypoint unless you're moving since it won't know which way you are facing if >you're stopped.

Are you sure about this? Agreed, without a compass the device can't tell which way it is pointing. But doesn't it calculate the azimuth from your current position to the waypoint by doing the math between the two coordinates? Otherwise, how could a GPS like the eTrex H or the eTrex 10 do any route following at all?

Bob G., am I missing something?

John S.
(jshann) - F
Re: Re: Re: etrex on 05/16/2012 20:57:29 MDT Print View

If the GPS has no digital compass, you have to be moving ~ 1mph? to get a heading. With a digital compass you can stand still and get the heading.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: GPS, Glosnass, Galileo and Compass Constellations on 05/16/2012 23:40:28 MDT Print View

"Btw the US GPS Constellation is in the process of failing due to a lack of funding and a delay in technology. In 5 to 8 years we will be dependent on Glosnass, Galileo and Compass."

Bill, give us your reference for this. Or, is it just an opinion?

Personally, I don't believe that for a microsecond.

For one thing, Compass tends to be China-only. Galileo still has tremendous problems getting off the ground, physically and financially.

Russian GLONASS has been good, then bad, then good again, and I call that unpredictable. Plus, we don't really understand the Russian government/military/management structure for it.

--B.G.--

Mike W
(skopeo) - F - M

Locale: British Columbia
GPS compass on 05/17/2012 00:35:18 MDT Print View

>> If the GPS has no digital compass, you have to be moving ~ 1mph? to get a heading. With a digital compass you can stand still and get the heading. <<

I hear this alot and it's not entirely true. When you are standing still your GPS knows exactly where you are and all of the major brands will have a screen that will tell you where North is... which sounds a lot like a compass.

I agree that you won't get an accurate bearing from the bearing screen but if you look at the satellite screen you will know where North is. The fact that the GPS has locked on to a bunch of satellite positions means that it knows where north is. It might not know which way your standing but why is that important? As long as I have a map, a distance to a waypoint (the GPS knows that) and can read the satellite screen to find the general direction, I don't have to be moving to know which direction to walk.

Explained very well here for those who are curious:

http://www.gpsreview.net/satellite-info-screen/

I think you made a good choice getting the newer version of the Etrex (Etrex 10) however, for the price difference, I would have recommended the Etrex 20. The feature set on the Etrex 20 is amazing! I've been using it for quite a few months now and can't believe what it can do. The fact that I can load my own custom map images as well as Garmin's Birdseye imagery makes the Etrex 20 an incredibly good value. I haven't once said "but I wish it did...", it seems to do it all.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: etrex on 05/17/2012 00:48:52 MDT Print View

"Bob G., am I missing something?"

James, not that I can see.

If you set aside any possible digital compass feature, a GPS receiver cannot tell which way it is facing or pointing if it is stationary. That is the primary reason why a few of the newer receivers have a digital compass added on. As soon as it starts moving in some consistent direction, it can tell the direction of progress. Where this gets messy is at very low speeds, because it can't tell what is intentional progress and what is simply position "noise" and sitting at one point. So, each manufacturer has built in proprietary fudge factors for these small details.

If a military GPS receiver is in a jet doing Mach 2, you need lots of these fancy fudge factors working together, and the sequential position fix rate is very high. At Mach 2, a tiny jiggle is a big error distance. In ordinary civilian receivers, the fix rate is much slower. In one particular model that I use, the fix rate appears to be about twice per second. That's still way overkill for what a backpacker needs for a maximum speed of about five or ten miles per hour. I've seen some receivers that have been modified to slow the fix rate down to about once per ten seconds, and the primary reason is to preserve battery life. To get the good out of that, they had to figure out exactly which functions could go to sleep and which functions had to stay awake full time.

The very simple receivers such as the old Geko display some position numbers well, but the "map" display is just about zero. The newest receivers have very complex mapping displayed, but they use lots more battery power to drive it.

--B.G.--

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: GPS compass on 05/17/2012 01:01:50 MDT Print View

Mike W., "Reading the Satellite Info Screen" on the GPS Review web site says nothing at all about determining your facing direction when you have zero speed.

"...but if you look at the satellite screen you will know where North is."

Nope.

"The fact that the GPS has locked on to a bunch of satellite positions means that it knows where north is."

Nope. You are completely misinterpreting what it is displaying and what it means.

The Satellite Info Screen can tell you where the various GPS satellites are in the sky, but that doesn't do you any good for knowing your facing direction. I've been reading Garmin screens for 15 years.

--B.G.--

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: GPS compass on 05/17/2012 04:25:38 MDT Print View

I'm with Bob on this.

Cheers

Karl Gottshalk
(kgottshalk) - M

Locale: Maine USA
E-Trex 20 on 05/17/2012 05:17:56 MDT Print View

I just bought an E-Trex 20 for a new toy after having a Geko 201 for many years. My phone and camera also have a GPS. Sitting on my couch in the living room, it acquired 10 satellites within the first 2 minutes of turning it on for the first time, none of my other devices ever picked up any. When I have done an out and back hike in heavy woods both tracks coincide exactly, something I had not seen before with the Geko or phone.

I subscribed to their online maps, but find I am preferring the free ones at GPSFileDepot as they are easier to read and redraw faster. So far I am very pleased with this purchase.

As always, YMMV
Karl

Jeff McWilliams
(jjmcwill) - M
Re: Re: battery life on 05/17/2012 05:32:26 MDT Print View

Watch out for poor or no GPS reception from Android or other smart phones while in remote areas.

I've been geocaching in various parts of northern Michigan. A friend tried to user her Smartphone's GPS function while I used a Lowrance Endura GPS. She couldn't get a satellite fix while we were in remote areas, but my GPS worked just fine.

Yeah, it's an anecdotal report. Your mileage may vary based on make and model of phone, etc.

Jeff McWilliams
(jjmcwill) - M
Re: GPS, Glosnass, Galileo and Compass Constellations on 05/17/2012 05:34:21 MDT Print View

Bill wrote:

"As a civilian GPS accuracy is deliberately degraded from the Military Standard."

Are you referring to selective availability? That's been disabled since the Clinton administration.

John Jensen
(JohnJ) - F

Locale: Orange County, CA
a phone for "us" on 05/17/2012 06:32:53 MDT Print View

I expect that at some point someone will do a phone a little more centered in GPS and battery life. It makes sense. We're a big enough market. Until then what manufacturers see as market "divisions" shape our choices. We suffer low phone battery life because makers think we prefer slim phones to 24 hour GPS life.

I was really happy with my old Etrex Legend (the blue one). The Etrex 20 seems a better more modern version. That said ... I'm just not hiking places where I really feel I need a GPS. So, it will be map, compass, and occasionally Droid X for me, for now.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: GPS compass on 05/17/2012 07:10:31 MDT Print View

You don't need compass.

Start walking in what you think is the right direction.

Look at the track points on the map on the GPS.

If you're not going in the direction of the waypoint, adjust.

John S.
(jshann) - F
Re: Re: GPS compass on 05/17/2012 07:52:47 MDT Print View

If that direction is off a cliff, up a bluff or into catclaw then you do need a compass.

Edited by jshann on 05/17/2012 07:53:25 MDT.

Mike M
(mtwarden) - MLife

Locale: Montana
weight on 05/17/2012 08:07:48 MDT Print View

looks like the 10 is 5 oz vs 3 oz for the 301/401, little longer battery life, but I've used my 401 on week long trips and still have battery life left to spare

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Re: GPS compass on 05/17/2012 08:08:04 MDT Print View

Whether you have GPS, conventional compass, or the sun - you need to look around and find a passable route - don't walk off cliff or whatever

With a conventional compass, if you're at a high area, and you see something you want to go to, you see what direction it is on the compass, and then you can keep going in the same direction even when you're in the forest and can't see it anymore

With a GPS, maybe you can locate the object you want to go to on the GPS map and then you can just look at your track on the GPS and if you're going in the wrong direction you'll quickly see it and you can adjust

Or, while you can see the object you want to go to from a high area, start walking towards it and look at your track on the GPS and you'll see which direction it is, then you can keep going in the same direction even when you go through forest where you can't see far away

I configure my GPS so the map always has North up. I hate it when the GPS trys to orient the map so it thinks up is the direction you're going, because that direction keeps changing so the map keeps rotating back and forth which makes me dizzy

My electronic compass is almost useless so I just turned it off - it also saves battery life I believe

Mike W
(skopeo) - F - M

Locale: British Columbia
GPS Compass... on 05/17/2012 09:06:20 MDT Print View

>> I've been reading Garmin screens for 15 years. <<

So have I, so what?

So for Roger and Bob, I will agree that if I do a cold start with my GPS and I haven't moved, then the GPS can't know where north is. This is a fact. I will also agree that if I was walking with my eyes closed and don't know which way I was walking then the satellite screen won't help me locate a bearing until I start moving again since I need to know my last direction of travel for the satellite screen to help with directions while stationary.

But if I have been moving and have stopped (which is what I think we are really discussing) then the satellite screen will show me which way is north and my previous direction of travel. It's a "feature" that you may not use or know about but none-the-less it's there.

The satellite page saves your last known direction of travel on the horizon circle on the satellite page and unless you are somehow disoriented and can't remember which way you were walking, then you can use this page to locate north. All I have to do is align the dot with my last known direction of travel and I will know which direction I was travelling and where north is (while I'm stationary). It's not the same as an electronic compass (which is handy if you are a geocacher that is spinning in circles looking for a cache) but it's a useful tool for the hiker that is on the move and occasionally stops to look at their map.

So to re-emphasize what I said in my initial post regarding the fact that a GPS is useless for locating your direction of travel while stopped, I will stick to my original statement which is "it's not entirely true".

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: GPS, Glosnass, Galileo and Compass Constellations on 05/17/2012 13:48:27 MDT Print View

" "As a civilian GPS accuracy is deliberately degraded from the Military Standard." "

"Are you referring to selective availability? That's been disabled since the Clinton administration."

Jeff, this is something different.

All of the time, there are two signals present in the downlink. One is the civilian signal on 1.57 that you may be familiar with. The other is the military signal on 1.2, and it has higher precision, but it is encrypted. So, unless you are an authorized DoD user with a valid crypto code, you will never find the military signal. I've seen it, and it is scary.

--B.G.--