12 Parallel Vs. 16 Parallel

[+chevy292]

I'm looking at getting a new gps. I'm looking at the new lowrance ifind explorer. But I noticed that it is only a 12 parallel, where earlier models with fewer features are 16. What kind of results will the change make? I'm new to this and I'm on a limited budget. Any help would be great.

[+welch]

12 channel is pretty common. Some are saying 14 or 16, but really you'll be lucky to see 12 all that often. You only need 4 to figure your location. Not sure what the reasoning for adding more channels is other than getting to say they have more channels... maybe the idea is too allow for new WAAS sats in the future??

[+JohnnyVegas]

I think par tof the reason for having more than 12 channels has more to do with marketing. ( It get some one looking to buy a GPS to start thinking they need lots of channels. You do not need 12 channels to find a geocache and in some cases you are lucky to be albe to get more than 5 or 6, but you casn still find the cache, 12, 14 or 16-they are just numbers. JUst pick a GPS with the features you want, they are all going to work.

[+El Diablo]

You might want to contact Briansnat. I know he did a review on the Lowrance. From what I gather he's a fan of their's and his opinion is well respected in our community.

 

El Diablo

[+ekanow]

Just wanted to say Hi to all! Will be attemping my first hunt as soon as it stops raining here in Staten Island NY. Geocaching seems like a great way to spend time outdoors and this looks like a great site to belong to and learn and learn and learn. Happy New Year to all!

[+Airmapper]

You'll do just fine with 12 channels. I'm a Lowrance user and find they have excellent satellite reception.

 

Hi Chevy292 and ekanow, Welcome to Geocaching and the forums.

[+Team Cotati]

I have always thought that you only needed 3 sats to determine your location so long as you do not need altitude info.

[+GeoJunkie]

This is my understanding of it: To get a 2D lock, you need 3 satellites. To get a 3D lock (includes altitude), you need four. The advantage you get from having more channels than that is you can have extra satellites locked in. That way, when you move through the woods or other area with varying coverage, you've got backups when you lose signals from some satellites. Plus, I think you have improved accuracy if you get more satellites.

[+briansnat]

moving to the gps units and software forum

[+EraSeek]

14 channel has 2 channels dedicated to WAAS sats, freeing up the other 2 channels for regular GPS sats. The 2 extra channels also increases the opportunity for a better fix in tough signal areas such as tree cover.

[Neo_Geo]

It won't make much difference now. I rarely get a lock on 12 sats as it is, and often times there are only 10 or 11 available above the horizon (showing blank areas where satellite numbers would be on the satellite reception page).

 

It seems like they launch a new GPS satellite every few months, so eventually the sky will become more and more crowded with GPS satellites and perhaps in a few years there might be 13 or 14 satellites in view at any given time. I think it'll be a long time before 16 channels will be useful.

[klenger]

I'm pretty sure that the GPS satellite constalation consists of 24 operationall satellites at any given time. Assuming that 1/2 of the constallation is below the horizon at any given time, then the most you will ever receive is 12. Since you can get a good 3D position with 4 sats, 12 channels should be more than enough.

[+JDandDD]

12 is fine. I think I've seen all 12 exactly once in three years. Most of the time there aren't 12 in the sky much less 12 that are high enough above the horizon to be picked up.

 

Typically I see 4-6 locked in and my accuracy is perfectly adequate for geocaching and road navigating.

 

JDandDD

[+WeThereYet?]

The more satellites you can track at the same time increases the accuracy of your position fix. Yes 4 will give you a position fix with altitude but extra satellites will increase the accuracy of that position fix (reduce the margin of error).

[+Crystal Sound]

I read somewhere, that most consumer GPS units only use 3-4 of the "best" satellite signals to determine a position. The remainder are tracked, just to update the ephemeris data, for use when the "current" satellites are no longer as useable.

 

This seems to be true for the units that I've used. There's been times I've received 10+ satellites, that I've had a relatively high PDOP / EPE. There's been other times I've only tracked 6-8 satellites, and had a lower PDOP / EPE.

 

If this is true or not, I am not certain. This might also vary for different GPS manufacturers, models, ect.

 

As I understand it for the professional (survey) units - the number of satellites, and the geometric relative positions, makes a big difference in the accuracy of the fix.

 

I have a large number of GPS based time reference clocks installed over a 13-state area. These units only require 4 satellites to obtain a micro-second accurate reference.

 

Like others have stated, there's only been a handful of times I've received 12 satellites on my unit.. 9 being a typical average. To me, 16 seems to be a "bragging rights".

 

With geocaching, who knows about the unit the hider had, and how good of a fix they had when giving coordinates. Getting to the 'exact' spot the coordinates state, is useless, if the they are 30 feet off anyways.

Edited January 2, 2006 by Crystal Sound

[+EraSeek]

12 is usually the most sats you can pick up other than the 2 extra WAAS sats.

You can however receive more than 12 on occasion.

Often some of those 12 are masked out being too low on the horizon to use at the time.

8 or 9 sats seem most common on average for usable sats.

I do often get 10 to 12 on my GPS.

I usually use WAAS so 2 slots are taken up by WAAS. They are also usable for navagation but not usually in the best position.

14 channels frees up those 2 WAAS channels.

I have an old Garmin 45xl. It is some version of a 8 channel.

You only use 4 sats at a time....

Would anyone like to use my old 8 channel??? I'll trade.

Big difference between my 8 channel and my 12 channel!!!

[+JohnnyVegas]

This is what I have reada also. The GPS will process data from 3 or 4 sattelites, It will track the other sattelites and process data from one of those if you lose a signal from on the sattelites you are currenty locked onto. In the older units from the early days of GPS technology if your GPS lost a signal it would take it several minutes to find a new sattellite to lock onto.