Suggested GPS for canyons/cover

[salmon_run]

In a few weeks I plan to hike to a site containing a number of 100+ year old mines. The purpose is to GPS map old equipment, structures, dams, etc. These sites are at the bottom of a moderately steep canyon and at least 75% is under tree cover (at least it was in 1983). My current handheld is a Garmin 60C with color TFT display. I am very concerned about not being able to get signal.

 

I've read dozens of reviews and almost settled on the 60CSx until I discovered the SiRFSTARIII chipset was replaced with MTK. I cannot seem to find anything on the sensitivity of the MTK chipset.

 

First, would an external antenna (e.g. Gilsson) significantly help my 60C in this situation? For this one trip I could live with an extra cable.

 

If I need to purchase another GPS, what units will give the best reception in these conditions? Even with periodic signal loss, the 60C has been fine for all my outdoor activities.

 

I really have tried to research this, but find more subjective rather than objective material.

 

Thanks in advance for any help.

[Dr Jeckyl and Mr Hide]

In a few weeks I plan to hike to a site containing a number of 100+ year old mines. The purpose is to GPS map old equipment, structures, dams, etc. These sites are at the bottom of a moderately steep canyon and at least 75% is under tree cover (at least it was in 1983).

 

Sounds like a job for an Oregon 550 with camera. If you took a picture of equipment, structures or dams, the pictures would be geotagged.

 

You can also do the same kind of geotagging using software like RoboGeo or even Google Earth, I've been told, but there's nothing as nice as having all the work done within the gps.

 

The image below is one example of a Oregon Geotagged photo.

 

 

This is the full picture taken by the Oregon - it's not a great camera, but it's pretty good.

 

The photo becomes a waypoint you can navigate back to, which is really handy sometimes.

Edited February 9, 2010 by Dr Jeckyl and Mr Hide

[+StarBrand]

Of my 13 GPS units - the one I would trust the most in such a situation is the Garmin Colorado 300. It even has an external anntena connector built in for extra receiving power. Excellent reception in many tough conditions - I would put it up againist any 60CSx out there.

[seldom_sn]

In a few weeks I plan to hike to a site containing a number of 100+ year old mines. The purpose is to GPS map old equipment, structures, dams, etc. These sites are at the bottom of a moderately steep canyon and at least 75% is under tree cover (at least it was in 1983). My current handheld is a Garmin 60C with color TFT display. I am very concerned about not being able to get signal.

 

I've read dozens of reviews and almost settled on the 60CSx until I discovered the SiRFSTARIII chipset was replaced with MTK. I cannot seem to find anything on the sensitivity of the MTK chipset.

 

First, would an external antenna (e.g. Gilsson) significantly help my 60C in this situation? For this one trip I could live with an extra cable.

 

If I need to purchase another GPS, what units will give the best reception in these conditions? Even with periodic signal loss, the 60C has been fine for all my outdoor activities.

 

I really have tried to research this, but find more subjective rather than objective material.

 

Thanks in advance for any help.

 

I've owned a 60CSX for 4 years and an OR300 for 3 months. I've done several side by side test walks and can't see any significant accuracy differences between them.

 

I've never gotten good track log results in canyons. My "test canyons" are Refrigerator Canyon and Echo Canyon, on opposite sides of Zion NP. If the satellites aren't in perfect position, the track logs can put you 1000 feet from the trail. The only way I think you might be able to avoid this is to use averaged waypoints. A Gilsson in your hat certainly won't hurt either.

[+Walts Hunting]

First of all nothing works well in canyons. You can only get a signal from a satellite you can see. As you look up at the sky in a canyon the slice of blue you see is it. So they are all the say there.

 

I would disagree with the Oregon recommendation. They do not get WAAS under most circumstances and if you walk close to a tree it disappears forever. I converted mine to a paperweight and bought a Colorado. Much better satellite reception.

 

I have taken them out together and the difference in how far from cache is stupifying. The Colorado is dead on under cover and the Oregon is hoplesssly lost. Great interface lousy GPS

Edited February 8, 2010 by Walts Hunting

[+Idahogreggory]

I have had real good success with my Vista HcCx in Hell's Canyon but I think it has the same chip set as your 60C so I don't see why what you have will not work just fine.

[+Native20559]

Of my 13 GPS units - the one I would trust the most in such a situation is the Garmin Colorado 300. It even has an external anntena connector built in for extra receiving power. Excellent reception in many tough conditions - I would put it up againist any 60CSx out there.

 

I agree, having both the Oregon, Colorado and 76CSX (very similar to 60CSX), as a matter of fact you may even find it helpful to purchase an external Gilson "active" antenna which will amplify your GPS signal strength and make it much easier to get a signal lock. Get the Colorado 300 or 400 series if you can, the 76CSX, 60CSX as close seconds. Excellent units all!

 

These folks make the best active antenna's I've worked with on a non-commercial basis and the 76CSX,60CSX, Vista HCX, and Colorado series are all compatible. Check 'em out at http://www.gilsson.com/garmin_gps/antennas/mcx.htm. It will be the best $20 you'll ever spend if you need accuracy under the worst of conditions.

 

Be safe.

 

N

[Dr Jeckyl and Mr Hide]

First of all nothing works well in canyons. You can only get a signal from a satellite you can see. As you look up at the sky in a canyon the slice of blue you see is it. So they are all the say there.

 

I would disagree with the Oregon recommendation. They do not get WAAS under most circumstances and if you walk close to a tree it disappears forever. I converted mine to a paperweight and bought a Colorado. Much better satellite reception.

 

I have taken them out together and the difference in how far from cache is stupifying. The Colorado is dead on under cover and the Oregon is hoplesssly lost. Great interface lousy GPS

 

I used both my 60CSx and Oregon side by side a few times during the first three months I owned the Oregon and didn't see any difference in accuracy or lock on sats when under cover.

[+Zurfco]

Quad maps.

 

- Zurfco

[+Searching_ut]

The equipment you have, will more than likely work as good as anything in the current consumer grade GPS line up. For trees, more sensitive often results in better results. In canyons, the opposite is often the case as the sensitivity can result in multipath reception. At any given time, you might find one particular receiver works better than the other, but it doesn't tend to be consistant, and knowing in the field which unit is the most accurate is all but impossible most of the time.

[msmurfy]

Hello:

 

Regardless of the equipment you use, this may help:

 

http://www.trimble.com/planningsoftware.shtml

 

M

[salmon_run]

Thanks to all for the replies. A Gilsson is in the mail for my 'old' 60C. I'll do some testing in the house, Bidwell Park and the canyons of upper park.

 

msmurfy, later today I'll download the Trimble planning software and play with it...thanks for the pointer.

 

More fun things to play with!

[segler999]

Sensitivity in deep canyons, and sensitivity under tree cover are two completely different issues. Apples and oranges.

 

First, canyons. No amount of improved sensitivity (chipset, antenna, whatever) is going to help you see a satellite that is separated from your gpsr by yards or miles of dirt and rock in the form of steep canyon sides that block the direct view of the satellite. So, inside a canyon, if you have a line of sight to a satellite (clouds and weather have little effect on this, by design), you can fix on it with any level of gpsr.

 

Second, tree cover. Here is where a more sensitive receiver, or a better antenna, can help. A few feet of wood or brush or leaves or needles is not the same as yards or miles of rock. So, a better receiver or antenna can, and does, improve the satellite fix under tree cover.

 

I see this all the time when I go hiking under dense tree cover in Pacific NW forests. My ole blue Legend (Garmin) rarely keeps a fix under tree cover, but my 60Cx (SirfIII) trucks along just fine with little problem. I can hike all day under Douglas Firs, seeing very little sky, and still get a good track from the 60Cx with very few missing points.

 

One of my hikes, however, takes me alongside a high and long overhanging cliff that blocks the entire sky to the south and about 1/3 of it to the north. Both the Legend and 60Cx lose the fix here. Nothing you can do about it short of getting more sky above you.

 

Some people talk about a more sensitive receiver being able to receive satellite signals reflected off opposite canyon walls as a way to "expand" the available sky. Same for tall buildings. I consider this to be a problem rather than a solution because reflections serve only to confound the location calculations.

[+StarBrand]

Actually the High sensitivity "can" help in some situations. It will help in getting a fix on a weak signal that an ordinary receiver will not see. Trees or not. Canyon or not.

[+splashy]

In a canyon the gps has a narrow view and even if you have an ext antenna to get a lock on a weak sat. it's still more or less inline with the other sat's, this might result in giving the user a more or less error on the location.

 

The good thing is, if you make a track from a to b, this track will be usable also the next time you go from a to b. From b to a there might be an error, but this error is consistent, so once you understand where the error lies you can use the same track.

 

Anyway, in canyons it is better to make a waypoint once in a while holding the gps high, so your body is not shielding the gps.

 

Buying an external antenna is a waste, I think

[+Red90]

The problem is that normally weak signals are reflected. The HS receiver do math to "guess" how many reflections have happen to figure out a location. When standing next to vertical wall, there are two solutions to the equation. One where you are and the other the same distance inside the wall. Every HS receiver I have seen will randomly bounce back and forth to the possible options, sometimes showing you a long way away. The older units would just tell you the truth, that they can't figure it out.....

 

In random multipath like trees, the HS receiver math CAN do some magic things to get you a reasonable fix. When it is not random such as being next to a cliff, they don't work so well. Every manfucturer's math works differently and changes with every firmware, so it is very hard to compare. You need to be very careful when reading reviews to know the firmwares and chips involved.

Edited February 9, 2010 by Red90

[+Native20559]

In a canyon the gps has a narrow view and even if you have an ext antenna to get a lock on a weak sat. it's still more or less inline with the other sat's, this might result in giving the user a more or less error on the location.

 

The good thing is, if you make a track from a to b, this track will be usable also the next time you go from a to b. From b to a there might be an error, but this error is consistent, so once you understand where the error lies you can use the same track.

 

Anyway, in canyons it is better to make a waypoint once in a while holding the gps high, so your body is not shielding the gps.

 

Buying an external antenna is a waste, I think

 

Buying an external antenna is a waste, I think

 

Have you even tried an external antenna? How can you make that kind of statement if you haven't?

 

If you haven't tried an "active" signal amplifying antenna your really missing out. Even my Garmin "passive" antenna does a kick butt job pulling in sat signals everywhere.

 

If you have a GPSr with room for an external antenna, give it a shot, you'll be surprised. And the price is right ($19 for a Gilsson active model)

 

Be safe.

 

N

[salmon_run]

Ordered the Gilsson Monday, arrived via USPS today. Following is my FIRST IMPRESSION:

 

Unit appears well made. The 9' cable is smaller (diameter) than I expected. Magnet strength appears more than adequate for the small profile. There are two small round outlines on the backing which I assume are for screw mounting (no instructions so screw size would be trial and error).

 

I did a quick test in the middle of the house (single story, wood frame, high ceiling, 12 and 12 pitched roof with composite shingles). STOCK 60C found three satellites. With the Gilsson attached three additional satellites, plus the indicated strength on the original three doubled.

 

Similar results in the back yard with an improvement from 14 to 4 in position accuracy.

 

One huge improvement is in maintaining signal strength while turning in a 360 degree circle and moving the GPS from a horizontal to vertical position. During this test the Gilsson remained pointed up while also being rotated the 360 degrees.

 

Other than having another device connected to the GPS the only negative I discovered is the connector. I ordered the unit with the 90 degree connector thinking the GPS would fit better in my case and sit flat on the dash. The antenna connector on the 60C is recessed in a curved portion of the case. The Gilsson connector will ONLY fully seat at one specific angle where the curved case is at it's lowest.

 

Will have to wait until the weekend for some practical outdoor testing.

 

I realize that no amout of additional gain will help when there is NO signal to boost. My hope is that the external antenna will improve signal strength in marginal conditions.

 

Thanks again to all.

[seldom_sn]

Ordered the Gilsson Monday, arrived via USPS today. Following is my FIRST IMPRESSION:

 

Unit appears well made. The 9' cable is smaller (diameter) than I expected. Magnet strength appears more than adequate for the small profile. There are two small round outlines on the backing which I assume are for screw mounting (no instructions so screw size would be trial and error).

 

I did a quick test in the middle of the house (single story, wood frame, high ceiling, 12 and 12 pitched roof with composite shingles). STOCK 60C found three satellites. With the Gilsson attached three additional satellites, plus the indicated strength on the original three doubled.

 

Similar results in the back yard with an improvement from 14 to 4 in position accuracy.

 

One huge improvement is in maintaining signal strength while turning in a 360 degree circle and moving the GPS from a horizontal to vertical position. During this test the Gilsson remained pointed up while also being rotated the 360 degrees.

 

Other than having another device connected to the GPS the only negative I discovered is the connector. I ordered the unit with the 90 degree connector thinking the GPS would fit better in my case and sit flat on the dash. The antenna connector on the 60C is recessed in a curved portion of the case. The Gilsson connector will ONLY fully seat at one specific angle where the curved case is at it's lowest.

 

Will have to wait until the weekend for some practical outdoor testing.

 

I realize that no amout of additional gain will help when there is NO signal to boost. My hope is that the external antenna will improve signal strength in marginal conditions.

 

Thanks again to all.

 

Please follow this up when you get some canyon data.

[+Red90]

On a 60C you should see a fairly good improvement based on my experience.

[+Entropy512]

As to the MTK chipset - I don't know if it is the original MTK chipset or the new MTK2 (I assume the new MTK2), but the MTK2 has a reputation for being a very sensitive receiver. The original MTK was the first chipset to be competitive with the StarIII (and even beat it in some scenarios), the MTK2 is a significant improvement. It has been in use for "puck" GPS units for quite a while. I have an MTK2-based puck logger and its performance is VERY impressive. I can stick it in my glovebox, log data, and when I review it on Google Maps I can usually correctly see which lane on the highway I was in at the time.

 

I would not reccommend the Oregon for weak-signal work. While it is an excellent unit with lots of great features, the STM Cartesio chipset is pretty "meh". Avoid the DeLorme PN-30/40 series for the same reason - they also use the Cartesio.