GPS info needed!

[Remix]

I will add my 2 cents with a thumbs up for Magellan. I have had a
Meridian Platinum for many years, and I never had a problem with reception under the canopy as reported by many Garmin users.

Its 2 generations old and still working ok.

Also, here's a comparison of a 60csx to the previous generation Magellan Explorist 600.
The Garmin unit did not do as well as the Magellan.

I'm sure that both units have their strengths and weaknesses, but I just wanted to add some balance to the thread.

 

[Papa Bear]

I will add my 2 cents with a thumbs up for Magellan. I have had a
Meridian Platinum for many years, and I never had a problem with reception under the canopy as reported by many Garmin users.

Its 2 generations old and still working ok.

Also, here's a comparison of a 60csx to the previous generation Magellan Explorist 600.
The Garmin unit did not do as well as the Magellan.

I'm sure that both units have their strengths and weaknesses, but I just wanted to add some balance to the thread.

Huh!

Did we read the same report? I just read that article twice and I fail to see any overall result that "The Garmin unit did not do as well as the Magellan." In fact the one test where the Magellan "seemed' better (spread of readings for stationary reciever) were due to built in averaging which is not the same as "settling in". Anyway this was billed as "Initial comparison". Wait for the full report and maybe then there'll be more "balance".

 

[DougPaul]

Also, here's a comparison of a 60csx to the previous generation Magellan Explorist 600.
The Garmin unit did not do as well as the Magellan.

If that conclusion is based upon the final graph in the linked report, it does not hold up. All the final graph shows is that the Magellan has more averaging--the accumulated distance is NOT a measure of accuracy. Averaging may improve the accuracy when the GPS is stationary, but may degrade the accuracy when the GPS is moving. (Simple standard deviations would have been far more meaningful.)

Comparing two GPSes is a very subtle art--GPS receivers are very complicated beasts. For instance, all GPSes have to operate through short signal dropouts--older Magellans were slower to declare a loss-of-signal than were Garmins leading some to conclude that Magellans were better at holding a lock. (They weren't--they were just feeding the user an inaccurate dead-reckoning position while indicating that they still held a lock.) (This comparison is several years old--I don't know how the newer units compare.) From reading this report, it appears to me that the reporter is somewhat knowledgable, but it isn't clear to me that he is knowledgable enough to avoid some of the pitfalls of making accurate comparisons.

Doug

 

[Remix]

I see 3 graphs showing that the Explorist 600 reports less drift when stationary than both Garmins, and data that the Garmin 60CSX reported traveling a mile while it was stationary on a desk, 5 times more than the Explorist.

Thats not too subtle for me. The displayed position on the Garmin is going to be wandering around more than the Explorist.

The Explorist is 1 generation old, and the Triton is the current generation with the Sirfstar III Chipset.

Doug- Apparently, the Garmin C Series definetly lose lock and do not report it to the user for many minutes (Its in the link above). I have not seen this behavior in the Meridian. If I cover the antenna, I get a beeper and message screen saying loss of lock within seconds.

I just wanted to put some data out to counter the uncertainty and doubt put out by the people who prefer Garmins and to let everyone know that Magellan makes a good GPS unit.

Peace....

 

[DougPaul]

I see 3 graphs showing that the Explorist 600 reports less drift when stationary than both Garmins, and data that the Garmin 60CSX reported traveling a mile while it was stationary on a desk, 5 times more than the Explorist.

Thats not too subtle for me. The displayed position on the Garmin is going to be wandering around more than the Explorist.

One could easily take the Garmin track, smooth it, and sum the wandering to get a "total drift" plot similar to that of the Magellan. it is not a useful statistic for judging the accuracy of a GPS. All GPSes exhibit local wandering--the magnitude is far more important than the speed. (The reviewer himself commented on the greater amount of averaging (smoothing) used by Magellan.) Note that the reviewer stated that the long-term average locations were the same.

Doug- Apparently, the Garmin C Series definetly lose lock and do not report it to the user for many minutes (Its in the link above). I have not seen this behavior in the Meridian. If I cover the antenna, I get a beeper and message screen saying loss of lock within seconds.

What is the "Garmin C Series"? AFAIK there is no such thing--C means color display in the Garmin lines.

All of my Garmins give also give a loss-of-lock indication shortly after I block all signals too*. But the real situation is far more complicated than this (simultaneous loss of all signals)--you need 4 (or more) satellites to get a fully determined solution. What happens when you are down to 3, 2, or 1? Some very knowledgeable people (see www.gpsinformation.net) have reported the differences between Garmins' and Magellans' behaviours in these situations.

* You don't say what you are covering the antenna with. Covering the antennas of my older Garmins with my hand is adequate to cause loss-of-lock. My 60CSx does not report loss-of-lock because it is still able to receive signals. (A hand does not completely block the signal--it just attenuates it.)

I just wanted to put some data out to counter the uncertainty and doubt put out by the people who prefer Garmins and to let everyone know that Magellan makes a good GPS unit.

If you prefer Magellan's products over Garmin's, that is fine. However, the quoted article gives some evidence in favor of one, some evidence in the favor of the other, and some irrelevant evidence. IMO, it totals up to a wash (with some indications that the reviewer may not understand GPSes very well)--Iprefer better evidence and info when choosing my GPSes.

Doug

 

[DougPaul]

There are some reports that the MTK chipset in the Vista HCx has problems with low speed dynamics:
eTrex series H w/MTK chip -SW2.50/SW2.30:
http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=87583
SIRFIII x series chipset Type G update to version 3 available:
http://groups.google.com/group/alt....3599894e?lnk=gst&q=Vista+HCx#afaaa7203599894e
SIRF STAR vs Other GPS chipsets:
http://groups.google.com/group/sci....F+STAR+vs+Other+GPS+chipsets#fa33a30dea73536f

It appears that the Vista HCx has trouble distinguishing a 1-2mph walk from being stationary and thus gives less accurate statistics (moving time, speed, distance, etc). There was a software update which helped, but did not completely solve the problem. Comparisons suggest the 60CSx does better.

Doug

 

[psmart]

It appears that the Vista HCx has trouble distinguishing a 1-2mph walk from being stationary and thus gives less accurate statistics (moving time, speed, distance, etc). ... Comparisons suggest the 60CSx does better.

I've had trips where the 60CSx odometer was up to 30% higher than known trail mileage. Looking back, these were probably slow trips with lots of stops. And the GPS thought it was still moving during some of the time it was stationary.

I'm using the latest v.3.50/2.90

 

[DougPaul]

I've had trips where the 60CSx odometer was up to 30% higher than known trail mileage. Looking back, these were probably slow trips with lots of stops. And the GPS thought it was still moving during some of the time it was stationary.

All the methods of measuring trail distance seem to have their (different) biases...

Distinguishing between slow moving and stopped is an essentially impossible problem for a GPS. If the GPS is stationary, the indicated position wanders due the varying errors in the system. (A summed wandering distance is one of the statistics computed by the article in Remix's link.)

In my car, my 60CSx is generally within ~1% of the odometer distance. However, it is a lot easier to distinguish between moving and stopped in a car than when walking.

Guess you will have to hike faster if you want accurate distances...

Doug