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Guest alexm

Magellan 315/320 - Auto averaging off?

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Guest ClayJar

hat have no reception at all where they are hidden). With averaging, you can get a really good jumping-off point for the dead-reckoning (or triangulation) part.

 

Working around the existing auto-averaging is as easy as giving a nice wave. It'd be nice if they'd hurry up and put a setting in there, but it doesn't kill you as is. Being able to average waypoints you want to be precise is a strong plus. (I'm waiting to see whether Thales has included a setting for auto-av in the Meridians... If they haven't, I'm going to have to have a talk with those guys. icon_wink.gif)

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Guest ClayJar

hat have no reception at all where they are hidden). With averaging, you can get a really good jumping-off point for the dead-reckoning (or triangulation) part.

 

Working around the existing auto-averaging is as easy as giving a nice wave. It'd be nice if they'd hurry up and put a setting in there, but it doesn't kill you as is. Being able to average waypoints you want to be precise is a strong plus. (I'm waiting to see whether Thales has included a setting for auto-av in the Meridians... If they haven't, I'm going to have to have a talk with those guys. icon_wink.gif)

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Guest Geoffrey

Magellan GPS owners with Auto-Averaging:

 

First about GPS accuracy(EPE):

Most GPS units take a reading once per second. The GPS has a certain amount of error depending apon the quality of the signal received from the satellites as indicated by the EPE - Estimated Positioning Error as indicated on the GPS. Each second the GPS takes a reading, and that reading will be off by a certain amount of feet of error. Now walk slowly, like 5 foot per second walking speed, and your EPE is 18 feet. When the GPS takes a reading every second, each reading might be way off. Problem is that the slower you are moving, the more error there is, then finally it goes into Auto-Averaging if you are going too slow. The GPS will have a random error of several feet upon each reading from the satellites. The odometer and Speed indicated on the GPS becomes more accurate, the faster you go. So if you could go 2mph or less with Auto-averaging turned off, your Speed and odometer will be unreliable.

 

The Magellan company should be able to allow you to make adjustments in your GPS on how often your GPS takes a reading from the satellites to determin when to go into Auto Averaging, or to turn it off completely. The GPS units as of now, Auto-Average it's reading every second. There should be a built-in Auto Averaging Delay function, so that if you set the GPS down for a few seconds, it would go into Auto-Averaging.

 

Now to E-Mail Magellan to have a setting for Auto-Averaging put into their GPS unit's firmware for ON, OFF, and a Delay setting.

 

For general use have the Auto Averaging turned on or off, or have an Auto Averaging Delay setting, where you can set the number of seconds of delay. For slower walking like Geocaching, have the Auto-Averaging feature set to once every 5 Seconds or more. This will keep it out of auto averaging as long as you are moving about, and not sitting on a log. Example would be if you are searching for a cache, you dont want Auto averaging to take over. When you get to Zero distance, but dont see the cache, you would stop moving and stand still. The GPS then would start averaging after a few seconds.

 

What im saying is that the GPS goes into Auto-Averaging if you haven't walked fast enough, meaning that the readings are too close together. So it would be nice if you could turn off Auto-averaging, or set a delay of several seconds, to allow for slow walking without the averaging function interfering.

 

[This message has been edited by Geoffrey (edited 29 September 2001).]

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Guest ClayJar

That's actually not what we're talking about, but I'll have to reply when I get back from running sound at a funeral. (Sorry for not replying now, but one should not be late for a funeral.)

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Guest Geoffrey

ClayJar, I know that you are talking about auto-averaging kicking in while trying to locate Geocaches, and you want to turn Auto-Averaging completely off.

That would be fine for Geocahe hunting.

 

Id like to see a geocahe experince where you can seek a cache without the auto averaging kicking in, unless you set the GPS down, or stand still for a minute. Then it would go into auto-averaging.

 

Okay maybe this is all bad, and the GPS should never go into auto averaging until you mark your position, wait for it to do averaging for awhile, then save it as a landmark(waypoint), or exit without saving.

 

I had a Magellan, but now I have a Garmin 3plus, and a Etrex Vista. I usually have both of them in the car for Geocaching, Boating, Running, or hiking, but have been thinking of getting the magellan 315, but I had so many problems with several magellan GPS units, that I went to Garmin. The 4000xl and the colortrak were terrible magellan units. As far as Auto-Averaging though, the Magellan Colortrak was good in the woods or in the open, But the GPS housings on the magellans were crap(Garbage). I have looked at a Magellan 315, and it was pretty rugged with a good feel to it.

 

Okay For Auto averaging on is a Magellan, and For Auto averaging off is a Etrex Basic, thats what it looks like for now until they get there act together.

 

[This message has been edited by Geoffrey (edited 29 September 2001).]

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Guest ClayJar

s GPS receivers requires one of two things. The simplest method would be to query someone at Thales who has worked on the firmware. Barring this, the only remaining option is to perform an experimental analysis of the GPS receiver's auto-averaging characteristics given non-optimal GPS signal reception. Unfortunately, my pre-experimental tests indicated that as soon as I blocked all GPS signal reception to my Magellan, it went into satellite search mode, and so the experiment I was contemplating is not possible.

 

Results and contemplation:

 

Only Thales Navigation can tell us which auto-averaging trigger function is implemented in the firmware. The word of mouth coming from that direction is that it is the speed that is important, which implies the standard auto-averaging assumption. It is worth noting, however, that the MAP 330 is not subject to the same auto-averaging characteristics as the GPS 300-series receivers. I had to move at a displayed speed of 0.0 miles per hour to keep my MAP 330 averaging, and it broke out of averaging without even hitting 0.1 miles per hour. It should be assumed that the Meridian line will continue the MAP 330's behavior, and since I have yet to have the auto-averaging bug bite me, I'd say the better Magellans (the MAP 330 and Meridian series) will have no problems at all.

 

(This ought to be enough to whet any scientific appetites present, eh?)

 

[This message has been edited by ClayJar (edited 29 September 2001).]

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Guest Geoffrey

This is why I got rid of Magellan, and Got a Garmin 3plus.

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Guest alexm

quote:
Originally posted by ClayJar:

Only Thales Navigation can tell us which auto-averaging trigger function is implemented in the firmware. The word of mouth coming from that direction is that it is the speed that is important, which implies the standard auto-averaging assumption. It is worth noting, however, that the MAP 330 is not subject to the same auto-averaging characteristics as the GPS 300-series receivers. I had to move at a displayed speed of 0.0 miles per hour to keep my MAP 330 averaging, and it broke out of averaging without even hitting 0.1 miles per hour.


 

I think you just hit the nail on the head. My 320 won't break averaging until it hits 2.0 mph, the lowest speed reading I've seen it register.

 

I could deal with 0.1 mph. It's having to go from 0-2 mph in heavy ground cover that makes it aggravating... and I've got the scars to prove it!

 

I did some research as you did... I can stop averaging by stopping the satellite signal. This lasts for about 20 seconds before the unit goes searching for satellites. This does accomplish my personal task-at-hand (what's the EPE?), but is still quite annoying.

 

I made a condom out of standard run-of-the-mill aluminum foil (the kind you'd make a hat out of if you were trying to keep the government satellites from reading your thoughts). Slipping it over the antenna shaft seems to disrupt "lesser than adequate" signals as you'd normally find in relatively dense tree cover.

 

Obviously, I'm NOT going to carry the aluminum condom around with my GPS for these occasions. It does seem to work though...

 

...

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Guest ClayJar

Have you tried the "hula-wave" (as it has been dubbed)? Just give your unit a nice arm's-length wave (like you're starting a hula-hoop). If you give the unit a nice broad swing, you'll break the auto-averaging speed barrier momentarily, and that's apparently all it needs. (We all need a good thwacking now and then.)

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Guest Ron Streeter

This is an interesting (I guess) subject which has been explored in several threads since I started geocaching in Feb of '01.

 

I own a Magellan 315 and am familiar with the weird things that go on sometimes in regard to this issue.

 

On the other hand, I have found all 76 of my finds with this Magellan and I have placed all 28 of my placements with this Magellan. I think there were concerns about 2 of my placement coordinates.

 

My point is, do we need to be concerned about this issue for our purposes of finding a plastic container in the woods?

 

If I was using one of these devices to get myself to a camp in the woods, or a dock on a river or lake, I would be happy that it got me to within 50 feet...I could see the dock or the camp. I also think I can live with the 20 to 50 foot limitation when looking for a 6" square plastic container.

 

Just my humble opinion.

 

Ron

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Guest ClayJar

Yes, this discussion is probably not that necessary. In fact, for me at least, it's 100% academic, as my Magellan MAP 330 doesn't have the same issues as the lower GPS 300-series receivers. Does any of that make this discussion not worth having? Nah. It's good to study things and learn how they work (and try to make them work better) even if it's not that important. icon_smile.gif

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Guest ClayJar

Yes, this discussion is probably not that necessary. In fact, for me at least, it's 100% academic, as my Magellan MAP 330 doesn't have the same issues as the lower GPS 300-series receivers. Does any of that make this discussion not worth having? Nah. It's good to study things and learn how they work (and try to make them work better) even if it's not that important. icon_smile.gif

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Guest arffer

button for averaging, or it can be solved by buying a Garmin III+ or V.

 

For us, one or the other is going to happen, its up to Magellan as to which way we go.

 

------------------

Team CacheCows of Wisconsin

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Guest ClayJar

quote:
Originally posted by arffer:

Once I realized the cause of our hunting problems was the Maggy auto-averaging, yes, it became a big problem for us. Big enough that if the Meredian line does not have the ability to turn off auto-averaging, we're buying a Garmin III+ to replace our 315.


STOP!!!

 

Um, I guess that was a little too loud (I got carried away... sorry). Anyway, what I was about to say is that AFAICT the MAP 330 does not have the averaging problem the GPS 315 has. It took extreme concentration (and very slow, controlled movement) to manage to get even 15 feet while still averaging with my MAP 330.

 

I would venture to say that the Meridian line will probably duplicate the functionality of the MAP 330 (where it involves auto-averaging), which means it will be no problem at all (whether there is a toggle or not). Under heavy tree cover you may still have a few cases of the slingshot effect (where your fixes lag behind your position and appear to snap past you when you stop moving), but those would be due to impeded reception and multi-path errors, not averaging.

 

(And interesting aside: I've been under heavy tree cover and holding my MAP 330 still to average, and a few times it has even been bumped out of averaging by the fluctuations in the coordinate fixes. It very rarely happens, but I'd say that it shows that they got auto-averaging right in the MAP 330 -- and by induction, I'd say that they obviously must have gotten it right in the Meridians, too.)

 

[This message has been edited by ClayJar (edited 01 October 2001).]

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Guest arffer

That's good news, cause our preference is for one of the new Meridian units.

 

Keeping in mind that we have no interest in built-in map capability, nor the ability to upload maps, refurbed Garmin GPSIIIs on eBay going for under $150 are looking real attractive.

 

The GPSIII has a quad antenna (not patch), it has manual averaging, and it allows tracking breadcrumbs based on time (down to 1/sec) which allows for the shotgun approach to averaging. The only difference between the III and the III+ is the memory that allows map uploads.

 

For under $150, I'm real torn. Spend way less, and get the shotgun pattern thrown in that the Maggys don't have.

 

I should also mention that personally, we don't want WAAS for hunting (be okay for hiding) as we want SOME challenge left icon_wink.gif

 

[This message has been edited by arffer (edited 01 October 2001).]

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Guest arffer

That's good news, cause our preference is for one of the new Meridian units.

 

Keeping in mind that we have no interest in built-in map capability, nor the ability to upload maps, refurbed Garmin GPSIIIs on eBay going for under $150 are looking real attractive.

 

The GPSIII has a quad antenna (not patch), it has manual averaging, and it allows tracking breadcrumbs based on time (down to 1/sec) which allows for the shotgun approach to averaging. The only difference between the III and the III+ is the memory that allows map uploads.

 

For under $150, I'm real torn. Spend way less, and get the shotgun pattern thrown in that the Maggys don't have.

 

I should also mention that personally, we don't want WAAS for hunting (be okay for hiding) as we want SOME challenge left icon_wink.gif

 

[This message has been edited by arffer (edited 01 October 2001).]

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Guest vader

I just found this topic and boy am I glad. I thought I was going crazy. I have a Magellan COLOR TRACK and I have been having problems constantly when finding caches. know that I know the wave trick I am anxious to see how it works. Thanks Vader

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Guest AZMark

When I die I don't want no coffin, thought about it all too often. Just place a cache and let it read, Auto-Averging made him cease to breath.

 

(my humble apologies to James Taylor)

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Guest Geoffrey

If you had the Garmin 3plus, you would be overshooting the caches too. In some woods, the trees really mess with the reception. With the Mag 315 just stop about 100 feet away, then let the m315 average for a minute, then take a bearing using it and a real Magnetic compass. Put away the GPS and do a search of the area. If you have to, get out the GPS and Compass again to get a bearing to the cache. I recomend a Sighting Compass, to get a bearing on the cache's spot. An m315 and a sighting compass, is far better than any expensive GPS alone, so dont get rid of the m315.

 

The person placing the cache, may have had a 50 foot error, and you might have a 50 foot error. That adds up to 100 foot total error.

 

I know that this thread is about getting Magellan to get rid of the Forced Auto-Averaging on the m315. So it looks like the hula wave for now. There is a GPS in the same price range, and that is a Garmin GPS 12.

 

[This message has been edited by Geoffrey (edited 05 October 2001).]

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Guest ClayJar

Um, the point of this thread is discussing auto-averaging in Magellan GPS receivers. While sighting with a compass is definitely a good technique (and one I use on almost every single cache I hunt), it has nothing to do with auto-averaging. (It has a lot to do with the topics that cover it, and there are several.)

 

If you've been walking slowly through the brush for a while, you might even be past the cache by the time you stop. You can let it settle a while, but if you have a way around auto-averaging (or a way to turn it off), that's a good thing.

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