Eight vs 12 channels

[Guest Peter Scholtz]

My friend wants to sell his old Garmin which receives eight (8) channels. It's about three or four years old.

 

My question is, what is the difference between an eight and 12 channel GPS?

 

Can the old eight channel GPS be used for Geocaching?

 

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Peter Scholtz

www.biometrics.co.za

[Guest Moun10Bike]

You can find info on the benefits of a 12-channel receiver at http://celia.mehaffey.com/dale/why12.htm. Basically, the 12-channel receivers are faster at achieving satellite lock and do better under canopy than 8-channel receivers. This is because the 8-channel receivers are actually 1- or 2-channel receivers that split their time among 8 satellites.

 

The 8-channel unit would work for geocaching, but would only be comparable to a 12-channel if you have a clear view of the sky. Once into the trees, you would definitely prefer the 12-channel.

 

Jon (Moun10Bike)

 

[This message has been edited by Moun10Bike (edited 25 May 2001).]

[Guest tak1]

you guys ever actually tracked 12 sats? I can routinely track 8, and one day I got 10, but I haven't seen my unit track 12.

 

LK

MB, Canada

[Guest Hard Slate]

My understanding is with more channels you link up or aquire sats. quicker and more efficiently. They also hold their lock better.

 

[This message has been edited by Hard Slate (edited 25 May 2001).]

 

[This message has been edited by Hard Slate (edited 25 May 2001).]

[Guest Hawk-eye]

Just a bit more info that no one has mentioned.... the older 8 channels would only lock on one satt. at a time then move to the next the newer 12 channel ... while them may only get 8 or more channels depending on the topography or satt. geometry, are pegging all at the same time. Thus you get better lock in tree cover ... when you loose a satt. you still are communicating with others. Not to mention, the old units took forever to lock when you turned them on. It's sort of like my old Compaq III computer ... size of a sewing machine, 12 meghtz ... state of the art and "so small" .... DEFINITELY wouldn't go back to it from my Sony Viao. Same with the GPS ... Can't wait to see what we have in a few years.

[Guest Seamus]

quote:

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Originally posted by tak1:

Have any of you guys ever actually tracked 12 sats?

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I can frequently get solid locks on anywhere from 6 to 9 sats "in the open" on my Garmin eMap without resorting to an external amplified antenna. This increases dramatically when I plug in the amp -- I have had up to eleven full-strength locks under these conditions. Usually, I don't resort to using the amplified antenna unless I'm hunting in the deep trees and can't otherwise get a reliable lock.

 

The orbits the sats are in make it somewhat rare to have 12 birds above the horizon at once, but it happens. I haven't actually locked 12 at once yet, but there's no doubt in my mind that if I had the amp plugged in and the "stars" were right, I could do it.

 

Not sure just how much accuracy (if any) this would add to the reading, but it sure is neat to see a "full house" of little blue bars on the screen!

 

-- Seamus

KC5UGQ

Frederick, MD

[Guest MikeLINY]

I got my vista yeterday. After enabling WAAS this mornig I had 12 "birds" but only 11 were corrected by WAAS. oh well can't get much better than that.

[Guest Peter Scholtz]

Tell me more about WAAS.

 

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Peter Scholtz

www.biometrics.co.za

[Guest Iron Chef]

I was out sailing yesterday and I left my eTrex Venture on and stowed it in the main cabin pretty deep in the ship. I was surprised to find out that it was still tracking all 12 sats with WAAS locks with no problem, even though the ship's hull. The elevation was even correctly measured as -2 feet which I thought was pretty dadgum neat since I have never ever had that feature work right. I still can't get over how it will work in a boat with no clear view of the sky and then how it has trouble in light tree cover with a view of the sky. Oh well.

 

I forgot to mention that my accuracy was being reported as 6 feet. :~) I was in heaven.

 

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-Iron Chef

_ _ _________________ _ _

agefive.com/geocache/

"But a big booming voice from the sky is exactly what you have found..."

-Contact

 

[This message has been edited by Iron Chef (edited 01 June 2001).]

[Guest AZMark]

At present there are two geo-stationary satellites serving the WAAS area (Inmarsat IIIs: POR (Pacific Ocean Region) and AOR-W (Atlantic Ocean Region-West).

 

from http://www.gpsinformation.net/exe/waas.html

 

would be hard to lock on 11 waas with only 2 in the air. unless they've launched a bunch more since March

[Guest Silver]

quote:

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Originally posted by AZMark:

would be hard to lock on 11 waas with only 2 in the air. unless they've launched a bunch more since March

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Agreed. But since those two sats downlink error correction updates about all the other sats, you can have WAAS updates on all the signals you can receive. These are usually shown as a small letter "D" at the top of the signal strength bar.

 

Silver