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Is My Gps Too Old?

AJ of Dunbar

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Hey yall. I just found this site today and found my first cache today :D Any ways I got this GPS years ago during some kinda promotion with bridgestone (tires). Its a Magellan Blazer 12 GPS. I never really had any use for it I remember trying it and it never seemed to get a location right (I would set the location knowing where it is). Then use to GPS to guide me there and it was always off.


Well i used it today And the gps was off again. I found the cache cause i had looked at some spolier pics. But when i got there the gps cord. were off and it said i was .10 miles away. Well about 15 minutes I was gathering up my stuff to leave and my gps said i was now only .02 miles away and my cord were nearly spot on. But it took a while for it to get this new info. I have pictures here




What do you all think, is it too old? I got it in 1998 brand new. Today it proved it will get your cordination but it seems to take a while.


any help is very much appreciated.




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The Blazer12 was a great unit when it was new. (That's not to say it's still not a good unit.) The biggest drawback to using the Blazer12 is the accuracy. It only shows coordinates to the hundreth of a minute of Lat&Long, which work out to be about +/-350 feet. Newer GPSrs measure to the thousandth of a minute, or about +/-35 feet. If the Blazer is allowed to sit in a certain position fow a few minutes, it will continue to acquire data from the satellites and average and update its position (a.k.a. averaging). This would be why when you were getting ready to leave the cache site the coordinates were closer than they were when you got there.


In 1998, when you received your Blazer12, the Global Positioning Satellites had a function called Selective Availability (SA) turned on. This only allowed selected persons and/or agencies (essentially military) to receive precise position data. Other, non-selected persons were still able to receive and use the GPS signals, however they were not as accurate, and had an error factor of +/- 100 meters. In its time, the Blazer12 was fairly cutting edge and could get a position about as accurate as allowed.


In May of 2000, SA was turned off, effectively increasing the possibility of obtaining an accurate position on the face of the earth by ten fold - from 100 meters to 10 meters. Geocaching began as a celebration (if you want to call it that) of the SA being turned off, and consequently the caches placed are measured to the thousandth of a minute of Lat&Long, which is more accurate than the Blazer12 is capable of without a few minutes of averaging..


The Blazer12 still is a good unit for some applications such as hiking or backpacking where 10 meter accuracy isn't an issue. The Blazer 12 will get you back to within 250 feet of your car (or other start point). If you can't find your car from there, you've probably got no business being outside. As far as caching with it, you can still use it, but it may raise the difficulty of the caches a bit and will probably require some more thinking on your part. It can be done though, my brother-in-law used a Blazer12 to find quite a few caches until he upgraded to a Magellan Meridian Gold.


Let me also say Welcome to Geocaching! Hope this helps. If you have any other questions, don't hesitate to post them here. There are many helpful people in these forums. Good luck on your hunts!

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It only shows coordinates to the hundreth of a minute of Lat&Long, which work out to be about +/-350 feet. Newer GPSrs measure to the thousandth of a minute, or about +/-35 feet.


350 feet? I'd go along with around 85 feet.


Cheers, Kerry.

My bad. One hundreth of a minute of Lat&Long is 60-80 feet and one thousandth of a minute of Lat&Long is about 6-8 feet. I was thinking of the pre-SA vs post-SA numbers being 100 meters vs. 10 meters. Sorry for the confusion.

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I am not familiar with your particular model Magellan, but my first was a low-end one and now I use a Magellan 315.


The BIG difference with older models was that they were three channel SIMPLEX units, meaning they looked at one satellite at a time and once three sats were found would begin to display info......the longer you stand in one spot the better.


The newer ones are all twelve channel MULTIPLEX, meaning they will look at up to twelve sats simultaniously and give you real-time info instantly. Much more accurate.

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So Spoo, does this mean that with a Magellan 315 (I just dusted it off to try this) I get the same accuracy but need to wait for it to do some averaging or is it inherently less accurate than the newer 12 channel models?

To my knowledge, the 315 (my model of choice) IS a 12 Channel Multiplex unit. I find mine to be extremely accurate. I have 40,000 miles of experience with it and have no complaints.

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From the Magellan GPS315/320 User Manual...


Performance -


Receiver: 12 parallel-channel technology, tracks up to 12 satellites to compute and update information with quadrifilar antenna.


Acquisition Times (under optimal conditions):

- Warm Approximately 15 seconds.

- Cold Approximately 1 minute.


Update Rate: 1 second continuous.



- Position 49 feet (15 meters) RMS (with Selective Availability turned off).

Velocity 0.1 knot RMS steady state (with Selective Availability turned off).

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This was just the thread I was looking for.


I have n Apelco GPS15 that I bought for a sailboat about 9 years ago and I have been trying to use it for geocaching. We have found the three caches that we have tried so far but even with averaging set to High it jumps around quite a bit and it has taken us quite a while and we use other clues like tracks or distrubed leaves. Spending a while hunting can be part of the fun but not if the GPS is sending us off track.


I think this unit does 5 simultanious satelites and it claims .01min accuracy even though the readout goes to 1000ths. It is also a little big (1.21 lb).


I have seen that some of the new models contain:

- storage for maps

- electronic compasses



Are these new features important for geocaching?


You might think that I am trying to talk myself into a new GPS but I don't want to spend the money if its not going to make much of a difference. It would be cheaper to keep feeding batteries to my current one.


Many thanks.



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The features that some of the new GPSr models contain are not necessary for Geocaching, but they do make life a little easier sometimes.


Downloadable maps are nice because the GPSr can help you plan a route to your destination. As you get closer to your waypoint, you can see where the cache is relative to the surrounding roads and/or terrain.


Electronic compasses are nice when you have a bearing to as part of a cache, such as used in an offset cache. I use a compass quite a bit when caching (although my GPSr does not have an onboard compass) to help me locate the caches when I get nearby, or just to get my bearings with the surroundings.


WAAS is a nice thing sometimes. WAAS can and does cut the error of a conventional GPSr in half but that may or may not be a good thing for caching. Remember, there are two GPSr units used in caching - the unit used to obtain the coordinates of the cache (the cache owners GPSr) and the unit used to find the cache. In reality the finder is trying to reproduce the coordinates of the hider. If the hider's GPSr does not have WAAS, and the coordinate has an error, a finder's WAAS enabled unit will only get you closer to that error. The accuracy of the coordinate is only as asccurate as the least accurate unit of the two GPSrs used. You'll still be able to find the cache, it's just the the WAAS didn't help you do it.


One feature that you didn't mention (you kind of did) is the size. Newer models are much smaller and can fit in your pocket. The Garmin ETrex models for example are tiny - just a few ounces - and have some of or all of the other features (and more) you are wondering about. And they start around $100 for the less expensive models.


Hope this helps and good luck on your hunts.

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I am new to geocaching. I found my first benchmark and cache today. (Feb 23)

I have had a Magellan Meridian XL since 1995. I was pleased to discover it was almost dead on the coordinates at the benchmark and the cache. This unit has been in my desk drawer for the last five years. It took about 1 hour to acquire a signal when I first placed it in operation again. After several days of continuous operation with a 12 volt gel cell it will acquire a signal in about 2 minutes. I use an external antenna and turn it off when I go in the parking deck at work. In my case old seems to work very well.


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