Garmin GPSmaps 64s and 60csx

"Still, the most important thing about a GPS is the ability to get my location and that's what I bought it for and it works great for that."

I could not agree more.

We had a backpacking trip planned for Kings Canyon N.P. and I knew the theoretical route off the map. I saw that we would need to head cross country to Granite Pass. So, from the topo map, I picked off the coordinates and plugged those into my GPS receiver as a theoretical waypoint. Days later when we were out there, we headed toward Granite Pass. As we got closer, I did a GOTO for Granite Pass, and it displayed an arrow direction to follow. Slowly the distance to Granite Pass reduced, so I put my head down and watched only the GPS receiver and not the terrain. Finally the display said Miles To Go, 0.00. I stopped and looked. The survey monument for Granite Pass was seven feet in front of me.

–B.G.–

Yea Bob… and I bet you didn't concern yourself much whether that was 5 miles or 5.1 miles or 5.2 miles or 5.3 miles did you? :)

billy

Or more in line with the discussion, you probably didn't care much whether that was 5.0, 5.5 or 6 miles, did you Bob???

billy

Billy, in general, I don't believe any official trail lengths when I am deep in the mountains. It's going to be whatever it is with or without Mister Garmin.

–B.G.–

The fact that the laws of physics causes error is fine.

If there's a Garmin software bug that's causing an error, and they don't care about it and never fix it, that's a little more annoying.

But not new that a company doesn't fix a software bug

It might not be a software bug. It might be an undocumented feature.

–B.G.–

> 10-20 feet of accuracy is plenty for me, and i understand that means for every
> reading the gps takes it could be adding 20 feet of inaccuracy every 10 seconds
> or so for hours of hiking.
Wrong.
Completely wrong.
Any reading will have an error associated with it. But those errors are random and are not cumulative. You start at A +/- 20'. You end up at B+/-20'. Whatever errors happen along the way do not matter. In fact, because they are random, they average to zero.

> the GPSmaps 64s does a REALLY good job of being accurate enough when it gets its
> readings on the move, it just doesnt seem to REPORT that information in an accurate
> way.
Wrong.
You are making an assumption here that what it is reporting is wrong and that your other information is right. Have you ever considered that the GPS might be (approximately) right, and that your other information might be WRONG?

> a problem with Garmin's firmware design
Nope.
The problems are your assumptions (and expectations).

Look, a GPS is a good tool for giving you a static position. ALL else are frills.

Cheers

"Wrong.
Completely wrong.
Any reading will have an error associated with it. But those errors are random and are not cumulative. You start at A +/- 20'. You end up at B+/-20'. Whatever errors happen along the way do not matter. In fact, because they are random, they average to zero.

But as I understand it, because they are random means that they will NOT average out perfectly each time, and it's entirely possible or indeed probable that the gps will read incorrectly because of it, right? If the thing reads 5 feet in front of me at one point, then 20 feet behind me after i've traveled 100 feet in a straight line, the GPS will read i've traveled 75 feet. It's now entirely possible that as I travel the GPS will make up the "lost" distance, but it's just as likely to add more or simply not make up the difference, especially as terrain changes. 20ft every 10 seconds or so was just a worst case scenario for the sake of discussion.

"Wrong. You are making an assumption here that what it is reporting is wrong and that your other information is right. Have you ever considered that the GPS might be (approximately) right, and that your other information might be WRONG?"

Yes I have! and as I've stated numerous times in this thread, when I take the tracks home and put them in Basecamp, they read closer to the maps, guides, and trip reports. When I clean up the tracks by filtering out points and removing clusters of wandering when stopped, they read even closer to reported distances. The tracks are consistently correct in Basecamp before/after correction and consistently incorrect when read from the device.

Now MAYBE every single trip i've gone on this year has under-reported distances from a variety of sources and MAYBE the GPS is actually recording accurately even WITH the wandering and bad points and I can actually walk 4mph with stubby legs and 30lbs of weight on me and MAYBE it's actually garmin basecamp that is being consistently incorrect. But it just doesnt seem like the probable option and when other GPS users report 10% inaccuracy and not 25-50, that just seems to tell me somethings wrong.

If you want some real GPS excitement, you need to experience a GPS blunder.

Due to the way that GPS works, sometimes there are two possible PVT solutions (position, velocity, time). However, one of those solutions is improbable. It is at high elevation, going too fast, or something like that. The probable solution is within 300 miles of its last position and going at a sane velocity. Nearly all of the time, the receiver will pick the probable solution, and that is what is displayed. On rare occasions, it will pick the improbable solution and display that. That is when the fun begins.

I had my receiver in my car, and I backed out of my garage, so the receiver started picking up satellite signals while the engine was idling. After about twenty seconds, it displayed the first fix. It had me about thirty miles away, at high elevation, and traveling at 400 miles per hour. The human in me knew that this was incorrect, so I shut it down, counted to ten, and then started it up again. This time it took thirty seconds or so to display the first fix, and it was correct. It had a slightly better view of satellites, and that made the difference.

As long as you have a good view of the sky, then this is very rare. Unfortunately, some users do not scrutinize the resulting display or wonder about what it means.

–B.G.–

My experience with the GPSmaps 62st is that the unit Trip Computer displays about 10% high, after comparing to the data back home in Basecamp. So, if it says I walked 18 miles, I subtract 1.8mi and I actually walked 16.2. It's annoying, but I've come to automatically do it. I only look at it a time or two throughout the day, I more-so use the data later for future trip planning.

Complete speculation: Its at least few generations away before someone comes up with a simple way to fix this complex problem WITH the handheld unit processing power. I also have the purchased $100 100k topo map sold with this unit, I'm not sure if the handheld uses this to be more accurate or not, BUT basecamp certainly does, including the topo lines.

"But as I understand it, because they are random means that they will NOT average out perfectly each time, and it's entirely possible or indeed probable that the gps will read incorrectly because of it, right?"

Steve, you are thinking too much and not getting the right conclusions.

Most of the errors that you find on GPS are random noise errors. So, if you plot out your stationary position over time, it looks like a snail track around a single point. If you average those over time, it will be almost perfectly on your true position.

The distance traveled can be quite a bit in error. Part of that is because you have no idea what assumptions the receiver is using about what you want displayed. You have no idea what the sampling interval is. If there are "outliers" in the track, then Kalman filtering is supposed to delete them from the results. However, you don't know what parameters are plugged into the Kalman filtering, so you don't know what kind of a job it should be doing. As an example, you plug in different parameters if you are in a military fighter jet, and different ones if you are in an automobile, and different ones if you are in a sailboat on water.

Remember, it is a physics problem.

–B.G.–

The "Odometer" I use with my iPhone 4s (MapMyRun) seems to work well and consistently reports the same distance within better than 0.1 of a mile over the same course (2.8 miles). The GPS typically tracks the actual path within 20 feet, often within 5 feet. Every now and then I get a "flyer", but not very often.

I would think that the Garmin could do as well. My Garmin 60csx always seemed to report a very accurate position while I was in Yosemite. Plenty of granite to reflect signals, but I don't remember any time when it was off. It did 'wander" a little while stopped, but they all seem to do that. The only real issues I encountered were user error. ;^)

Bob, I appreciate your simple explanations on the practical use and limitations of GPS units. So my question to you is as map and compass guy who will be traversing the Brooks range next summer and will be bringing along a gps for the sole purpose of confirming my static location. Reassurance. Which unit would you recommend that is not filled with so much fluff. My mind is a confused and hazy after researching this.
Any help would be greatly appreciated.

John

John, it is difficult to tell what you are requesting. If you are asking for a product recommendation, I have none. There are non-commercial web sites that do a good job of that. Every GPS receiver that I have owned for the last 17 years has been some model of Garmin, but I have used hundreds of a different brand.

If you want simplicity, then there are some models that are great. Some are great for being lightweight. Some are great for low battery consumption. Note that the fancy color screens with maps generally draw more battery power.

If I had to go to the Brooks Range right now, and if I had to buy a new receiver for this trip, I would buy one of the most recent Garmin models. But, that is just me.

You may already be bringing a satellite communicator, and it probably has a GPS function built in, but that may or may not be user friendly.

The most important tool that I would bring is a paper map. A magnetic compass is important also, but there are two problems. One is that when you get to that part of Alaska, you may not be able to find any good landmarks to triangulate with. The other is that when you get up to 65 or 70 degrees N latitude in Alaska, the magnetic declination gets pretty severe. That is not a show-stopper, but it just means that you have to do your math better in order to get a good solution.

As you get progressively nearer to the North Pole, the GPS satellites are still totally workable, but they are lower in the sky (nearer to the horizon). It is a good thing that there are not a lot of big obstacles there to ruin the sky vew even more. As time goes by, the DoD is making the GPS constellation more and more robust. However, the birds all fly on 57 degree inclined polar orbits, so the weakest spots are directly at the poles. By that, I mean that the satellites are least likely to be directly overhead.

–B.G.–

As you get progressively nearer to the North Pole … the weakest spots are directly at the poles

Aren't the GLONASS satellites supposed to give better coverage in the far north? Would it not pay to get a GPS that also has GLONASS compatibility (such as some of the Garmins)?

–MV

I think that there is a mutual lack of trust between Russia and the U.S.A.

For years, GLONASS had terrible problems when the constellation was not being maintained. That's over now. Since there is more Russian territory in the higher latitudes, they optimized GLONASS differently for that.

Russians worry that the GPS satellite system might be turned off in case of hostilities. U.S. users worry the same thing about GLONASS.

OTOH, I can get good information about the status of the GPS satellites, and I think GLONASS is much harder.

–B.G.–

>>>Every now and then I get a "flyer", but not very often.

There is a place where I do runs with my dog and we pass under some massive high-tension power lines, right at the base of the tower. I get a flyer there almost every time on the Trip Data (Odometer) screen indicating something like max speed 573mph and an added distance of 1.6mi, but it doesn't appear on the track. I assume the "data smoothing" kicked that one out. I figure that there must be a lot of signal reflections ricocheting around those huge steel beams.

I don't have a product recommendation. I've used military GPS but now tend to stick with the base models like my beloved and now dead Garmin Geko (sniff… RIP) and my current etrex (or whatever it is) which is a few generations old.

I get, understand, and appreciate your desire to stay found, know your pace, and know your distance. While they've come a long ways, even a high end GPS is going to struggle from time to time when you're traveling in deep valleys and under thick forest canopies. Some GPS will do better than others in those situations but from what gather from what you've written here, I think you're in a position of diminishing returns and I think it's highly unlikely that you're going to find the level of precision you're going for here from a consumer grade GPS.

You wrote:

"But i don't know if i want to give up glonass and perhaps other features like being able to download and use caltopo maps and/or birdseye on my 64.

I may get the 60csx simply because I'm really curious how it compares, and would like to do a comprehensive field test/review comparing the 64, the 60, (possibly the oregon 650), and my phone GPS with Backcountry Navigator Pro. But since I wouldn't be able to return the CSX if it's not as good, I'm a little apprehensive on throwing down $150 just out of curiosity.

So basically the question is, I'm wondering how others like their Garmin GPS? Are they getting worse with each generation? Do you like your 62 or 64s? Are you happy with the 60csx? Is there a different GPS you prefer?"

Here's how I accomplish these goals.

a) Use the GPS to confirm what you already know. Look at your trip ahead of time. Measure the distance from known point to known point. Predict your ETA the next known point based on your past performance. Check your watch when you get there to see how close you were to your prediction. Establish a catching feature (eg stream, road, etc) that will set off an internal alarm if you somehow miss your known point. I am at a point where I use my watch instead of a pace count to determine distance.

b) Analyze your GPS data at the different known points and de-conflict the data with what you're seeing on the ground.

c) You can upload your waypoints from Caltopo to just about any Garmin GPS (at least the one's I've played with) that have some sort of computer interface. Conversely, you can download the trip data to Caltopo and review it there later. I just print the maps and use that instead of mapping software.

d) I personally turn off WAAS to save on processing power and battery life. It really doesn't solve any problems for me and it's not a feature I find that I need.

e) I've found GPS (for me, YMMV) are more useful for determining current location and using that information on a paper map to navigate with. This is a great way to get days/weeks out of a single set of batteries.

f) I much prefer a GPS with real buttons in the field than something with a touch screen.

So my bottom line recommendation would be to buy one of the eTrex GPS. I personally like having a barometric altimeter (even though I have one on my watch) so I'd personally opt for the eTrex 30 but I'm sure the eTrex 20 is perfectly fine for most people. Sounds like it doesn't take much to fill up the memory on the eTrex 10.

I'm sure that some of the GPS like your current model probably lock in on the satellites faster but I believe that this is a case of diminishing returns.

"I figure that there must be a lot of signal reflections ricocheting around those huge steel beams."

Yes, that is very likely. Also, there might be a great deal of RF interference radiated out from some bad power line components. I've seen some severe multipath in the metal and glass canyons of Manhattan at street level.

I've seen GPS reception completely fail in a number of situations. It doesn't happen very often, and it doesn't last long. The military would call that a jammer, and soon after that they call it a target.

In each domestic case that I saw, the suspect was either a known microwave radio transmitter within view, or else an unknown microwave radio transmitter somewhere in the vicinity. The L1 (civilian) frequency is 1.57GHz, and there isn't too much else that operates around there. The L2 (military) frequency is 1.2GHz. The L3 (NUDET) frequency is 1.8GHz, but if it lights up, it is time to get your head down low.

–B.G.–

"I've seen GPS reception completely fail in a number of situations. It doesn't happen very often, and it doesn't last long."

Happens all the time in downtown San Francisco in the glass and metal canyons. At least it failed enough to loose the position fix.

Ian, was your military land nav training with or without GPS?

Mine was in 1970, long before we had such a thing.

"d) I personally turn off WAAS to save on processing power and battery life. It really doesn't solve any problems for me and it's not a feature I find that I need."

WAAS might be good if you are in a jetliner on approach to Atlanta with Category 3+ conditions.

WAAS was designed purely to allow jetliners more vertical accuracy for landings.

"f) I much prefer a GPS with real buttons in the field than something with a touch screen."

Me too.

Touch screens can get pretty iffy in bad conditions, like when they are iced over. Or, if your gloves are iced over.

–B.G.–

"Happens all the time in downtown San Francisco in the glass and metal canyons."

It can help a little if your receiver has a good position fix and a current almanac with ephemeris data… before you enter the canyon. Still, sometimes it gets very ragged.

I was helping install a big fixed-station GPS system in Manhattan one time, on Park Avenue. First, I used my handheld receiver on the sidewalk, and reception was spotty. The equipment room where the fancy system was going was on the fifth floor, and we were afraid that we were going to have to put dual antennas on the roof, which was above the fiftieth floor. The cable engineering and expense would have been massive. Then I noticed that there was a narrow landing that surrounded the seventh floor, and it could be reached from the equipment room with a few hundred dollars worth of cable. So, we mounted one antenna on one corner of the building looking down Park Avenue, and another one on another corner looking down Lexington Avenue. If the satellite constellation had problems on one, it would be better on the other, so the system sat there and switched back and forth between redundant receivers. There is more than one way to skin a cat.

–B.G.–

"Ian, was your military land nav training with or without GPS?"

Without. GPS came later and typically (from the days of yore) only squad leaders and above had them so I didn't play with them much until later in my career. I had to carry a SLGR which was almost like carrying a VCR. Now you need a background in XBox One or PS4 to keep up with BLUEFOR and all the techno stuff that's out there.

When I joined, you left the arms room with a single weapon. When I ETS'd, you left the arms room with a shopping cart full of gadgets, the sum total cost more than my first three or four cars combined.

Nothing to do with the OP but the radio I learned on was the PRC-77 and didn't see a SINCGAR until I was in for a few years. I proved to the world, and certainly our RTO, that I can't play with anything more complicated than a rock when I Z'd out our SINCGAR as we were leaving the wire on a mission in Bosnia. I tried not to do more than change channels and talk on the mic after that.

Aaaaaand back to the OP.

"PRC-77"

Just to show the age, I used the AN-PRC-25. It was always great fun to dial the frequency dials around to snoop on the enemy frequencies.

–B.G.–

Just to toss in a few website resources:

This site has a listing of Garmin models containing "high-sensitivity" chipsets (definition not provided), which the reviewer recommends.

http://gpstracklog.com/compare/garmin-handheld-gps-comparison-chart

If you click on one of the model links on the far left, it will take you to a review page for that model, in some cases containing a performance comparison with other models. For instance, this link (eTrex 20) compares its tracklog performance to two other models, a GPSMAP 60CSx and a GPSMAP 62s:

http://gpstracklog.com/2011/10/garmin-etrex-20-review.html

There is also a geocaching test that shows the eTrex20 performs much better using GPS+GLONASS vs. GPS alone.

Finally, this links to a couple of tools that may be useful in planning how much coverage you'll have at a particular location (haven't tried it myself yet):

http://freegeographytools.com/2007/determining-local-gps-satellite-geometry-effects-on-position-accuracy