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Losing Sattelites


NoRain
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My first experience with a GPS was a couple years ago using my Brothers Garmin. He bought his originaly for Flying and this is what the unit is designed for. It is a Garmin GPS III.

Note this unit has an external antena, it is connected to the unit but swivels up. I do alot of hiking off trails in heavy tree cover and this unit was great!

Anyway after using it a bit I decided to go out and buy my own.

 

I decided to stay with Garmin but researched some of the different models and made my decision.

I bought the Garmin eTrek Summit. It seemed to be more designed for the Hiker.

It was a SWEET little device. I was so Happy.

It has many GREAT features.

Then I got it in the woods and it kept losing sattelite connections. There was Light tree coverage and semi clear skys. Now The GPS III was keeping Sattelites through trees Overcast Skys and I also had it hooked on my belt, it never lost satelites. I decided the Summit must be broke, right? So I brought it back told them it didn't work and got the same model.

But once again I had no Luck.

 

I tested both models side by side and the Summit lost sattelites while the GPS III kept its connections.

 

So my question...

Does anyone know is the Antena in a GPS III superior to the Summit?

 

This was Two years ago and now the other day my Brother & I found our first Cache icon_smile.gif and I am seriously thinking of getting another one.

 

I also read here in the forums that Magelin is known for better coverage through heavy trees.

Is that true and why?

 

Anyway thanks for any and all replys.

 

Scott

 

~BLIZZARD~

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As Anders stated there is plenty of reading in reguards to this matter.

 

A quick explanation would be that the Garmin 3 you were using has a quad-helix antenna and the eTrex summit has a "patch" antenna. Both are good, but the helix does a better job at locking onto satellites under heavy tree cover.

 

I was once in the same boat as you. I had an eTrex Venture that would drop signal in the woods quite often but since I upgraded to the Garmin 5 (quad-helix) I get a solid lock under almost any conditions.

 

1 downfall to the Etrex line is there is no way of upgrading the antenna or attaching an external one.

 

Hope this helps...Kar

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What they said. But here is something you can check out first hand. I've seen that the patch antanea is better in an environment with vertical edges. While my GPS would lose lock with by a cliff the Vista (same patch antanea as the Summit) kept on chugging along.

 

=====================

Wherever you go there you are.

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I tried a Garmin once. I had it for about three days before returning it. With a question like this you may get a lot of responses like my GPS is better than yours because some people can be very loyal to the brand they use.

 

The quad helix performs much better in tree cover. I had my Magellan Sportrak Map with me on my first hunt with the Garmin. The Garmin could not hold a satellite at all while the Magellan held a solid lock on 5 or 6 satellites at all times. I was not in heavy tree cover I was on top of a mountain nothing higher than me to block the view, the trees didn't have any leaves because it was winter. I think it was a fair test they were side by side and one unit just didn't perform. I wish now that I had taken a picture of the two side by side so that I could just post the picture when this question comes up. Well in the end I returned the Garmin and bought a Magellan Meridian Platinum and I am very happy with the unit. Whether you by a Magellan or a Garmin I would look for one with the quad helix antenna.

 

HTH

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WOW!

Like there IS a ton of talk on this topic...

Not surprising, as GPS's ARE the heart of this Great new "Game".

 

Thanks To All!

I have learned alot!

 

I'm going to get a GPS that allows a seperate Antena and I'm gonna run a wire to my Kayak Helmet and mount a Dish on top of it.

 

Great Idea! Ay?

 

Seriously though, I will continue my research of different brands and make a purchase within the next couple weeks.

During this buy... No Patches! Will be my motto.

 

Thanks again to all!

 

Scott

 

~BLIZZARD~W

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Don't let the patch discourage you. It is still a fine antenna. I definately recommend you study them a bit more and also keep in mind what kind of terrain you mostly traverse.

 

A quad helix antenna can give you poor performance in a canyon or valley while the patch will lock on and hold tight. They both have there strong areas and it should be taken into consideration as to where you live and will mostly use it.

 

Good Luck...Kar

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Just to let you know, when you buy an external antenna, it will almost undoubtedly be a patch antenna. It will also most likely give you a signal boost of anywhere from 5 to 20db or so. (The boost has little to do with the type of antenna however) Just to confuse you more, a good many of the antennas on the surveying equipment you see in the field are patch antennas. Trimble makes a fantastic multi-element unit, albiet very expensive. Furthermore, just about all of the GPS systems I've installed, or maintained in military equipment over the years have had patch antennas as well.

 

Most of the hype you see about "Quad helix" antennas being superior, is the result of the marketing departments. The two types of antennas both have some strengths when compared to the other, which means they also have weaknesses. Either one is a trade off.

 

That said, there are very real differences in behavior, reception, etc. of the different GPS receivers on the market. The differences are driven by the amplifiers, kaliman filters, effectiveness of the circuit layout to reduce noise etc. etc. With the exception or orientation preference, and some small differences in reception patterns of the two different antenna designs, the different antenna types make little difference.

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Decided after much thought I wanted two things from my GPS.

A Helix Quad but more importantly the option of an external antenna.

Also I wanted to have it waas capable.

 

I bought...

A GPS V

 

Really Happy with it.

 

Thanks for all the replyes & help!

 

Scott

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quote:
Originally posted by NoRain:

Decided after much thought I wanted two things from my GPS.

A Helix Quad but more importantly the option of an external antenna.

Also I wanted to have it waas capable.

 

I bought...

A GPS V

 

Really Happy with it.

 

Thanks for all the replyes & help!

 

Scott


 

 

Truly an excellent choice. icon_wink.gif Have fun with it. It'll serve you well.

 

"Gimpy"

 

--N2GLS--

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I'm going through the same gyrations...eTrex Legend/Vista, or Sportrak Pro. Using both for the last few days, here are some of my observations:

 

1) The Legend acquires a satellite lock faster in most conditions than the Sportrak.

2) In a hallway/vestibule entrance to my office building, the Sportrak maintains better sat reception.

3) In my backpack, the Legend tends to maintain better lock.

4) The Legend will show breaks in tracks when sat lock is lost, while the Sportrak throws in extra tracks to connect the lost track points - I dislike that very much as one time it showed my path to be through a house!

6) Under tree cover it seems a wash as both seem to lose around the same amount of time.

 

All in all, it was becoming harder and harder to decide which was better, they both have their good points...so...I picked up for comparison a Meridian Platinum unit. Right away, it seems to have better sat lock under all conditions than both the Legend and Sportrak. I don't consider it's size a negative, but the lack of a wrist strap is, IMO, a big negative. I may try to construct something but I don't know if it's worthwhile for that.

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I'm jealous of formula1. How'd you manage to get to play with multiple units without having to buy them? I had to buy mine to get to play, limits me somewhat on what all I can play with.

 

Sounds like your comparison results with the sportrak and Legend mirror mine fairly closely. Having actually done all of my comparisons side by side, I wonder about the so called recpetion differences you see in the forums so much. I've personally found it a mixed bag, depending on lots of different factors. With me spending most of my time in the mountains, the legend actually seems to have the slight reception edge for me.

 

I find your observations on the Meridian intersting. I only got to play with one of those for a short period of time, but it seemed about the same reception wise as the sportrak. Unfortunately, I only got to compare in one canyon area, no different forests, houses or anything.

 

Regarding tracks, if thats something important to you, the latest eTrex series software upgrade really gives them the edge in that area. (By allowing you to use highly detailed track recording options without running out of memory) Not only are the receivers more accurate position wise when recording tracks, they record significantly more detail. On my last cache outing/peak bag trip, my legend recorded 2498 track points, while the sportrak only recorded 543. Both units set to their most detailed auto setting. With the Legend, you can look at your track on the way back down the ridge, and figure out if you came up to the left or right of the big narrow rock outcropping in front of you. With the sportrak, because of the accuracy and lack of detail issues you generally can't do that.

 

Just some data to make your decision even tougher. icon_biggrin.gif

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Searching_ut, I'm lucky to have a good working relationship with a local outdoor store, I spend a lot of money there (I'm an avid fly fisherman - a single fly outfit is quite expensive...), and they let me "purchase" a gps unit, try it, and if I don't like it (within a reasonable period of time) I can return it assuming it's in like-new condition. I don't abuse the policy and they know that they will end up with me buying a gps unit from them.

 

Right now the Sportrak is off the radar for me - since it's about on par with the eTrex, the tracking algorithm tips the scales in favor of the eTrex...so now it's between the Meriplat and the eTrex Legend...I will be trying them tomorrow to see how the tracking works with them, as well as extended treking through the woods.

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Hmmmm, that's not fair. I haven't really bought any new flyfishing gear since GPS came out that I can recall. One of my pack rods is fairly recent though, I may have bought it in the last 8 years or so.

 

Sad part of it all is that now I only seem to go fishing when I'm on backpacking trips, which isn't nearly often enough. The great part of it all is that you can get out and find great new remote spot with the mapping software available today, and of course the good old GPS units. I find that much more fun than geocaching even.

 

Good luck on picking the unit that works out best for you. You seem to be off to a great start.

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Sometimes one really needs to sort out some of the myths and misconceptions about this reciever or that receiver and sometimes even sort out why there are these "perceived" differences.

 

So one receiver locks faster then another in "most" conditions. So what are these conditions and just what is the time differnce?

 

"In a hallway/vestibule entrance to my office building, the Sportrak maintains better sat reception" if anybody is actually expecting this and thinks it's a attribute then they need to read the specifications.

 

"In my backpack, the Legend tends to maintain better lock" like if it's really relevent! again relate this to the actual specifications.

 

"The Legend will show breaks in tracks when sat lock is lost, while the Sportrak throws in extra tracks to connect the lost track points ..." and so they bloody well should, a lost signal is a lost signal and anything that wants to start interpolating is making assumtions, and that's not acceptable.

 

"Under tree cover it seems a wash as both seem to lose around the same amount of time" and so they should. When some realize what the overall controlling factor is then these types of comments simply won't exist.

 

I've also really never come to terms with how some companies can state accuracy fiquires that are better than what the "actual" system specifies.

 

Sometimes one really has to wonder if all this is simply manufacturer PR crap.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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Kerry, some interesting observations. Let me try to answer them as I see it:

1) Most conditions - in my car, outside in open sky, under tree cover, the Legend acquires lock faster than the Sportrak so far. Typically 20-30 seconds faster in good conditions, in iffy conditions (my car) more like 1-2 minutes faster.

2) The hallway/vestible, while not what they were designed for, is no worse than someone saying this gps got good reception in my house. It's an extreme condition and it is part of any good testing procedure. In order to rate performance, for instance of an automobile you do full redline runs for 0-60 mph, and 1/4 mile - do you really think anyone drives like this on the street? Also, most mfg don't state slalom times but car magazines also test this to find the stability limits of a car or truck. Yet it's the only way to know for sure which car peforms better than another one. Same for reception in a backpack.

3) I agree about throwing in extra tracks, I don't really like it, but different strokes for different folks - many people are very happy wiht their Sportrak and that's great.

4) Under trees it was a wash, but I am going to see how the Meriplat does against the Legend.

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A good test procedure is always subjective and not simply an ovservation as with GPS being dynamic, conditions as you will understand are constantly changing. Just because one has reception at a particular time in a particular place simply doesn't mean that will always occur.

 

As with any testing visual observations can be very selective as opposed to actually recording the data and using ALL the data over a specificed time frame.

 

I suppose the thing is that since conditions can never really be duplicated then it's difficult comparing this indoors reception issue as really there is simply no consistency. It's really not a comparison that one can base any judgement or decision on as far as single individual receivers are concerned.

 

This whole inconsistent issue of indoor reception is what defeats the 911 requirement in mobiles.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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To throw in a little bit more, took the MeriPlat and the Legend for some hiking/geocaching yesterday. The MeriPlat maintained better sat lock as far as I could observer, under good tree cover. Also, seemed to respond quicker and more accurately my true heading (used compass to verify this), the Legend seem to lag, or it would be more accurate to say that it required me to walk in one direction longer to get a good reading on my heading.

 

This morning used both in my car into work. The Meriplat drove me crazy with its tracking, grrr...on one section of highway, where there are a number of long curves, I can see it lay down tracks in a curve, then when the curve is finished, it straightens them out into 2 straight lines with a sharp angle connecting them - nothing at all like the real track I just layed down. I am going to change the tracking to auto detailed and see if that makes a difference - this Magellan algorithm of using averaging, is a real PITA.

 

At this point I am considering a Map76 or 76S for the combo of quad helix antenna, ability to use an external antenna, and hopefully better tracking algorithm (if it is the same as on the eTrex series)...

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