Magellan Gold, Frustrated at getting a fix

[Kitegirl]

Ok, I'm fairly new at this, I've found a few caches and now I want to hide one. I've found several nice spots but I'm frustrated out the wazoo in trying to get a fix on them. They are in light tree cover..I can still see quite a bit of sky. I've stood in one place for 15 minutes and my gold still won't lock in on a position. It wavers between 2D, 3D and nothing at all... The batteries are fresh, the unit is warm. Are there any tricks or quirks with the Meridians or do I just have a funky unit? It seems to work ok finding waypoints when I'm hunting, but getting an accurate fix in anything but absolutely clear open space is another story. Any suggestions greatly appreciated!

 

m

[+JetSkier]

When this happens, go to the satelite screen. How many satelites have you locked on to? Also, do the Lat and Long values keep changing? If you have several satilite locks and the Lat/Long values don't change, then you've got an accurate position.

 

I have a Meridian Marine and I haven't had any problems getting an accurate fix.

 

JetSkier

[Dale_Lynn]

Another thing to try is put a "marker" on the ground where you want to stash the cache. Walk away 50 to 100 feet from marker and slowly walk back to it and record position (on note paper). Do this from the four main compass points. The readings should be pretty consistent. This will give you a average position that should be pretty accurate for any cache "location".

 

Dale

 

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I'm Diagonally Parked, In A Parallel Universe.

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[+Searching_ut]

It's hard to say for sure what sort of reception you should be getting, because everyones definition of how much tree cover they have seems to differ. There are however several things you can do to increase the likelyhood of an accurate position fix.

 

To begin with, go to an area where the horizons aren't obstructed, and you have minimal if any tree cover. Let the receiver sit with good reception for about 20 minutes obtaining good almanac data.

 

In the area where you intend to place the cache, keep the antenna pointing upward, and the receiver as high up as possible and as far away from your body as possible. Use the satellite status screen to find a position to hold the unit that gives you as many good satellite signal bars as possible, then maintain the position for a few minutes letting the receiver average the position. (Holding your unit horizontally in even moderate tree cover can result in your loosing reception completely)

 

Finally, if you're still having trouble, try and find a friend who has a similar unit so you can compare receivers. It's possible you're could be defective.

 

Good luck

[greatwhite6]

I don't know about the rest of you Magellan owners but my Meridian unit here in SoCal gets killer reception. I sit in my living room and get 2 or 3 weak sat signals. Outside I usually have 9+ sats locked whether in trees coverage, canyons, etc. If you aren't getting "great" reception then I'd guess you have a defective unit.

 

Any belief worth having must survive doubt.

[+TotemLake]

You've heard of standing so close to the tree that you can't see the forest?

 

How big is that tree you're standing next to? The trunk may actually be blocking your ability to see the satellite constellation necessary for a better fix.

 

Go with what Searching_ut said on getting coverage, although I've found you don't really need to hold the unit over your head, just point the antenna upward so the object masking the horizon is your head and not your body.

 

Also, the Magellans do autoaverage their positions, so give about 5-10 minutes in the same location then save the waypoint. Move away and approach from a different compass point allow the same averaging to take place, then create another waypoint. Do a few more and then average your overall waypoint coordinates.

 

Cheers!

TL

[Kitegirl]

Lots of good tips here. I spent about an hour at one site playing around, using all of your suggestions. I think I got something that is pretty close, will go back later and try it again. Holding the unit up high helped in getting more satellites, from 4 to 8. Boy, my arm got tired. Thank you all!

 

m

[+blindleader]

Kitegirl,

 

I live in the Pacific Northwest, so in just a month of doing this, I've gained a lot of experience with the effect of trees. If the satellite you really need for a good fix happens to be through the densest part of a forest canopy, you're out of luck. If you're in a really dense forest, it doesn't matter what you do short of hiring a logging company to clear cut the entire area.

 

The technique I use when I know it will be a treeish day, is to use survey mission planning software to find the time when the maximum number of satellites will be a healthy distance above the horizon. The simplest free software I've run across for this you can download from Leica Geosystems. What this does is maximize the chance that I will be able to receive four adequately placed satellites at the location I’m interested in.

 

If, after standing at the site at the best time of the day, the satellite screen still gives you the sense of bad geometry (e.g. receiving few satellites clumped together), then you'll need to resort to tricks like TotemLake said and move away to where there is a good fix. What I would do different though is to stand at the good fix nearest to your point, take an accurate bearing and distance to your point and calculate the coordinates from your good fix.

 

I doubt that autoaveraging has a beneficial effect any more. I just wait long enough for my Meridian to catch up, less than a minute. Averaging was designed to eliminate the effects of Selective Availability, which inserted pseudo-random measurement errors for civilian receivers. Now that SA has been turned off, the primary measurement errors are due to the ionosphere, which I don't believe vary significantly over short periods. All you're doing by averaging for fifteen minutes is averaging the effects of the geometric positions of the satellites. If the geometry is deteriorating during this time, then your final average fix will be less accurate than the single fix you had at the beginning of the averaging period. There are several times each day satellite geometry goes from very good to very bad (read approximately unusable) in under half an hour. Disclaimer: This probably does not apply in vertically challenged parts of the country such as Florida, where you can usually see right down to the horizon in all directions most of the time. I suspect that in these locations and in airborne aircraft, the worst geometry of the day gives wonderful results.

[+TotemLake]

quote:

---

Originally posted by blindleader:

Kitegirl,

 

I live in the Pacific Northwest, so in just a month of doing this, I've gained a lot of experience with the effect of trees. If the satellite you really need for a good fix happens to be through the densest part of a forest canopy, you're out of luck. If you're in a really dense forest, it doesn't matter what you do short of hiring a logging company to clear cut the entire area.

 

The technique I use when I know it will be a treeish day, is to use survey mission planning software to find the time when the maximum number of satellites will be a healthy distance above the horizon. The simplest free software I've run across for this you can download from http://www.leica-geosystems.com/gps/almanac/index.htm. What this does is maximize the chance that I will be able to receive four adequately placed satellites at the location I’m interested in.

 

If, after standing at the site at the best time of the day, the satellite screen still gives you the sense of bad geometry (e.g. receiving few satellites clumped together), then you'll need to resort to tricks like TotemLake said and move away to where there is a good fix. What I would do different though is to stand at the good fix nearest to your point, take an accurate bearing and distance to your point and calculate the coordinates from your good fix.

 

I doubt that autoaveraging has a beneficial effect any more. I just wait long enough for my Meridian to catch up, less than a minute. Averaging was designed to eliminate the effects of Selective Availability, which inserted pseudo-random measurement errors for civilian receivers. Now that SA has been turned off, the primary measurement errors are due to the ionosphere, which I don't believe vary significantly over short periods. All you're

 

---snip---

 

---

 

Sorry to say that you are wrong on your assumption on the autoaveraging, however, as noted on Page 36 in the Meridian manual:

 

Averaging - Meridian is computing fixes; speed is near 0.0 so position is being averaged.

 

It has nothing to do with SA (Selective Availability). SA just means you're dealing with a larger error based on selected satellites civilian signals being turned off for general use.

 

In my experience over the past 4 months of ownership, the averaging actually has a significant role, and minimizes the spiderweb weaving while stationary. The weaving still occurs, but becomes smaller and smaller given time in the same spot.

 

Cheers!

TL

[+Cachetrotters]

Thought I'd place this here instead of creating a new thread. Seems as good a place as any.

 

Just ran across another satellite coverage prediction program, this one by Magellan.

 

Magellan Mission Planning

Here is where you can get it.

The almanac can be found here.

Users guide may be helpful.

 

don

[Vacman]

I now use a diving rod to help me in my hunt...

 

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If you drop your keys into molten lava just let 'em go 'cause, man, they're gone.<P>

<a href="http://www.vacsew.com/cache">Vacman's Cache Page</a>

[+Cachetrotters]

Divining rod

[Dale_Lynn]

quote:

---

Originally posted by Cachetrotters:

Thought I'd place this here instead of creating a new thread. Seems as good a place as any.

 

Just ran across another satellite coverage prediction program, this one by Magellan.

 

Magellan Mission Planning

ftp://ftp.magellangps.com/pub/software/utils/MP_WIN.ZIP is where you can get it.

ftp://ftp.magellangps.com/pub/almanacs/ can be found here.

ftp://ftp.magellangps.com/pub/Reference%20Manuals/Mission%20Planning/ may be helpful.

 

don

---

 

Help:

 

Your URLS dont seem to work.

At least with Netscape 7.02

 

Dale

 

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I'm Diagonally Parked, In A Parallel Universe.

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[This message was edited by Dale_Lynn on May 18, 2003 at 11:01 AM.]

[+Cachetrotters]

Sorry about that. Even selecting the URL's from the quote in your post opens up for me. Perhaps we'll have to wait for other input. But with IE they work fine. Here are the actual URL's. Just copy and paste into your browser URL line or dedicated ftp program:

 

ftp://ftp.magellangps.com/pub/software/utils/MP_WIN.ZIP

ftp://ftp.magellangps.com/pub/almanacs/

ftp://ftp.magellangps.com/pub/Reference%20Manuals/Mission%20Planning/

 

don

[+embra]

I'm not sure of the lingo here, but I think you need an FTP client to be able to access those links. I believe that the latest version of IE intergrates an ftp client in, which is why it works. Browsers without that plugin would have to have a dedicated ftp program, as Don noted.

 

You can find a number of such cadidates here.

 

Max

Often wrong but seldom in doubt

[+blindleader]

There isn't a browser around that I know of that doesn't implement an ftp client transparently. The last version of Netscape I used was at least two years ago and it certainly had it then. But who knows? Maybe it has lost the ability or made it more cumbersome.