Boomerang Effect !

[+gpsjeep]

I hear a lot of the magellan owners talk about their boomerang effect.

Now that the Explorists have the patch antenna, has the boomerang effect gone away in those models?

Thanks,

-Jeff

Edited May 5, 2005 by gpsjeep

[+jacques0]

I have had an ex200 for over a year and have never experienced any boomerang effect. I've noticed on other subject threads that other explorist owners (including owners of the new series) agree that this is not an issue w/ the explorists.

[+LostInTheFog]

Please excuse my asking, but I'm a newbie.

 

What is "boomerang effect?"

[+briansnat]

Please excuse my asking, but I'm a newbie.

 

What is "boomerang effect?"

Its the way certain Magellans process. They have some sort of averaging algorithm and it takes a while for the unit to "catch up". THis results in the user often overshooting a cache (or destination) by a hundred or so feet. As the unit corrects it sends them back to the cache (hence boomerang).

 

I saw this just the other day during a GPS/GIS seminar. We had all marked a waypoint, walked a half mile away, then used the GPS to go back to it. There were 10 Garmins in the group and 2 Magellan Sportraks. When we got to the the location every Garmin was within 10 feet, but both Magellans were 150+ feet off. We stood there and watched the Sportraks count down and it took about 30-40 seconds for the units to read the correct distance.

 

Many Magellan users deal with it by slowing down before they reach the cache site which allows the processor to catch up.

Edited May 5, 2005 by briansnat

[+ChileHead]

I always slow way down when getting close to a cache, as I almost always overshoot if I don't.

[+jacques0]

One time I was comparing a SportTrack Pro with my explorist 200, holding one in each hand. I marked a waypoint, then walked off a couple hundred yards, similar to what briansnat said (except not as far), then navigated back. The explorist took me right to the mark, w/i a foot, while the SportTrack Pro said I was still 100' or so away. I watched as the STP gradually changed its position until it was at least reasonable.

 

Now, having said that, I think it's common for any GPS to act a bit erratic when you're right at a GoTo destination. It seems that once you've arrived, the gps gets a little confused. I sort of take that as a sign that I'm within the position error.

[+Hard Oiler]

Having switched from a Meridian Gold to an Explorist 500 the boomerang effect has virtually gone - you can still overshoot but not the way the Meridians do. I'm still trying to do a back-to-back test but certainly the caching experience so far has the Explorist outperforming the Meridian (and I won't mention other makes )

[+JohnnyVegas]

While I have seen the boomerang effect with my Meridian gold and sport tracks, I have never seen it while walking when it was off by 100+ feet, in most cases it was about a 20 foot effect, the only time I have seen it at more than 100 feet was when driving. My guiess is that was do to the speed I was traveling at.

I havenot seen it with my Exlorist 500.

[+GOT GPS?]

I had the Meridian Platinum, but now have the SporTrak Color, and Ive had other older Magellans. The Auto-averaging has been a problem for me when doing accurate tracklogging, and Trip-Odometer info. The tracklogging does weird things, on curvy trails. My older Garmin's have been somewhat a problem, but the best GPS ive ever had, is the GPS 60C with WAAS turned on, so my Tracklogs look alot better.

 

My SporTrack Color, I cannot be without on any cache event now, because the temporary caches for cache events may be around bodies of water. No Garmin, or mapping for the garmins will do justice in this case. I am still thinking of the Explorist 500, if it's tracklogging is much improved over that of the older Magellans. I do like the idea of saving each tracklog segment to the SD-Memory card on the Explorist, and I believe this is much improved over the older Meridian GPS units. What I don't like of my 60C or any Garmin, is that when you save tracklogs, that strips out the date/time stamp from each trackpoint in the tracklog, and the tracklogs are reduced down to fewer trackpoints.

[+IVxIV]

What is "boomerang effect?"

 

There is another phenomena also sometimes attributed to Magellan & the boomerang effect..

 

It's been claimed that if some Magellan models lose their satellite signal lock they may not immediately indicate this, instead they would "hold" their last position and have you sometimes walking past your intended target. Shortly thereafter once a signal is reestablished the unit will correct itself and tell you to turn around to get to your goal.

 

This (if true) is also the beginnings of the old misconception, that Magellan "quad helix" antennas hold signal lock better than patch antennas while under tree cover. In fact, each type of GPSr would lose it's signal, but only the Garmin/patch would be honest & tell you this immediately, whereas the Magellan user would "think" they're still locked in and the unit would project or "guesse" your probable location.

 

Are the Explorists prone to this issue? If they lose signal lock will they report that immediately?

[+GOT GPS?]

What is "boomerang effect?"

 

It's been claimed that if some Magellan models lose their satellite signal lock they may not immediately indicate this, instead they would "hold" their last position and have you sometimes walking past your intended target. Shortly thereafter once a signal is reestablished the unit will correct itself and tell you to turn around to get to your goal.

One way around this is to Page back to the Satelite page once in awhile to check on your satelite lock, also you should turn on the satelite FIX alarm, also keep your Meridian or SporTrak at near a vertical angle in your hand.

 

To do this, go to the Satelite Page, then hit MENU, and on the SporTraks, scroll down to Alarms/Msg, and select that. Scroll down to GPS FIX, and select ON.

 

ON the Garmins, there is about a 30 second timeout where the GPS will give up and then tell you, that you have lost your LOCK, so when I hike under a bridge of a freeway, I run for it to make sure I get to the other side of the bridge in less than 30 seconds, and I don't have a break in the tracklog that way.

Edited May 5, 2005 by GOT GPS?

[+Renegade Knight]

While I have seen the boomerang effect with my Meridian gold and sport tracks, I have never seen it while walking when it was off by 100+ feet, in most cases it was about a 20 foot effect, the only time I have seen it at more than 100 feet was when driving. My guiess is that was do to the speed I was traveling at.

I havenot seen it with my Exlorist 500.

Night Stalker typicaly overshot by 20-50 feet max when he had a sport trac. The one time I borrowed it I'd heard if you take a few steps backwards as you get close you compensate for the effect. I tried it and didn't over shot. However doing something once, it's hard to tell if it really works or is just a fluke.

 

If the Explorists no longer do the averaging thing, I wonder if they now bounce around in a forest like the garmins do and the sport tracks etc. didn't?

[+gpsjeep]

If the Explorists no longer do the averaging thing, I wonder if they now bounce around in a forest like the garmins do and the sport tracks etc. didn't?

I also asked this this very same question in another thread.

I'm trying to decide whether or not I should invest in an explorist or just keep using my Meridian Yellow.

-Jeff

[+EScout]

I have used a Meridian extensively for 2.5 years, hiking and caching. I have not noticed a boomerang effect. I mostly am in areas with good reception. If I loose a sat. lock, which is seldom, it lets me know. Using a Meridian and 500 side by side, they appear to show the same distance, direction, and compass movement while walking towards a goto waypoint.

[+Cheminer Will]

One thing my SporTrak Color is very good at is satellite reception. I have also never had the boomerang effect happen to me with this GPSr.

[+embra]

I sometimes saw the BE on my MeriPlat, but have not yet seen it on my Explorist 500. The caveat here is that I've only had it for a few weeks.

[2oldfarts (the rockhounders)]

Using 2 Platinums and son-in-law uses a Gold. Have not experienced the "Boomerang". We have had our platinums over 3 years now.

 

John

[4x4van]

I use an ST Pro, and previously used a Mag 315. While the "boomerang" effect is there, in my experience it is very minor, perhaps 3-5 seconds. I've never overshot a cache by more than 20 feet, and even then only if I was moving really fast. And that's with over 150 finds. I have a hard time believing anyone is overshooting a cache by 100-150 feet due to the boomerang effect, unless they are moving at least 30 mph, or they have a defective unit (or perhaps older firmware?) in some way. I'm typically on foot, not in my car, when I get that close to the cache, and at 43 years old I know I can't run at 30mph!!

Edited May 6, 2005 by 4x4van

[+IVxIV]

One of you guys who are lucky enough to have both an older Magellan and a new Explorist can try a little test for us...

 

-Take both of them outside and wait until both have a good satellite lock. Then,,

-take both indoors quickly, to an area the units are certain to NOT possibly be able to maintain a satellite (thick walls,not near any windows)

-see how long each of them takes to report they've "lost their signal"

 

If the Explorists complains noticeably faster, then that might mean the boomerang effect is history

[+Marky]

One of you guys who are lucky enough to have both an older Magellan and a new Explorist can try a little test for us...

 

-Take both of them outside and wait until both have a good satellite lock. Then,,

-take both indoors quickly, to an area the units are certain to NOT possibly be able to maintain a satellite (thick walls,not near any windows)

-see how long each of them takes to report they've "lost their signal"

 

If the Explorists complains noticeably faster, then that might mean the boomerang effect is history

Unfortunately, the eXplorist 600 gets such good signal, that it will actually track in my house now, even downstairs (my Plat and STC don't), so I wasn't able to do the test you wanted. The good news is that it kept the lock.

 

--Marky

[+Flyfishermanbob]

I'm convinced this is a function of the algorithm that Magellan uses to handle Waas averaging , in the UK Waas isnt fully operational .... and Magellan software doesn't look at the "ignore data" bit..

 

When I enable Waas, the compass is sluggish and unresponsive as is the countdown of distance to waypoint ....with Waas disabled it is responsive and instantaneous ..... try it for yourself ....

[+maleki]

My Magellan Meridian always overshoots by 100 feet or so. My wife goes right to the cache with her Explorist 100. I just drive now - she finds the caches...

[+Hard Oiler]

OK - I've attempted the definitive test and I think I have confirmed that the Explorist shows less of a boomerang aka slingshot aka overshoot effect than the Meridian.

 

First my definition. The effect is due to the reported position lagging the actual position so that when you arrive at a predefined waypoint (ie a cache) the GPS still shows that you have not got there - so you finish up overshooting and having to double back. It's a result of a combination of factors. Data acquisition and processing speed, averaging of previous positions into the current position, the speed and directness of your approach. It can also be effected by signal reception or loss of signal since, if the GPS doesn't know where it is it can't update the previous position.

 

I picked a situation which would maximise the effect. A 340 metre (sorry I'm metricated) relatively straight trail running roughly East/West from an open area though lightly wooded terrain (trees are deciduous and only just starting to leaf out) to a final point under a large tree (yes there is a cache in it). Meridian Gold (Rev 5.35) and Explorist 500 (Rev 5.157) in each hand held at the rough optimum angle (Meridian towards vertical, Explorist towards horizontal). Start and end points were carefully measured with at least 10 mins of averaging - both GPSr's gave the same position. Walked at my usual geocaching pace (brisk) with no stopping to view the scenery. Rather than overshoot I stopped at the end-point and took the GPSr readings at timed intervals to see how long it took them to catch up to the actual position. I converted the difference from the actual position into distance which would represent the degree of overshoot. Conditions were good, I had WAAS lock and both GPSr's typically showed a 5 metre EPE.

 

 

My conclusion: under these conditions both overshoot but the Meridian overshoots much more than the Explorist and the Meridian takes significantly longer to recover than the Explorist. In practice, where you would normally slow down and start looking around as you approach the cache, any overshoot would likely not be noticeable with the Explorist but would still be noticeable with the Meridian.

 

Now all I need is a Garmin to repeat the test . Any volunteers?

[+BlackBuck]

I use the sport trak map,I set the alarm to go off at one hundred ft then wait to see what it does some times its right on and other times it takes a minute to catch up.By the way I have over twenty five hides and there have been no complaints about my co;s being off.

[+EScout]

In my test, with a Meridian Green (4.02) and eXplorist 500 in each hand. I walked toward a super-accurate benchmark (adjusted-- 1cm accuracy) When I got to the bronze disk, each GPSr was showing the coords to within one or 2 thousandths of a minute right when I arrived. Over time, they each appeared to average, with the thousandths digit moving up or down slightly. I concluded they performed the about the same. This disk was of course, in a very open, good reception spot.