Jump to content

Is "SA" Back In Effect?


Didjerrydo

Recommended Posts

I'm noticing that the Colorado 300's position seems to wander all over the place when it is left at a stationary position and the map is zoomed in to the 80' scale. This makes me think of the pre-2000 years when "selective availability" was in effect and civilian GPS units gave rather evasive positions due to the DOD scrambling the signals.

Perhaps, if this is inherent in these units themselves and maybe this is why Garmin chose to not let the map scaling be zoomed in any tighter than 80', instead of the 20' scale with previous units? Are owners of earlier units also seeing this wandering or is this unique to the Colorados?

Link to comment

This has been present in my 60Cx as well. When the unit is in poor reception conditions like indoors or under heavy canopy it would be pronounced. My 300 will record this kind of effect, too in those conditions. And no, SA is not back :D .

 

Well, what's your take on the maximum 80' zooming in on the Colorado? I can't believe that a new whizz-bang unit has totally taken a step backwards to this level. Seems as though this is really going to be a terrible hinderance when geocaching?

Link to comment
Well, what's your take on the maximum 80' zooming in on the Colorado? I can't believe that a new whizz-bang unit has totally taken a step backwards to this level. Seems as though this is really going to be a terrible hinderance when geocaching?

I find this interesting as well - my current GPSr, the Explorist, zooms to 100' - and I've used that zoom level probably once or twice geocaching (out of maybe 6 or 700 finds with it) - I usually only zoom to 250', and then watch the compass arrow. Perhaps I should file this under 'you don't know what you're missing', but I can't imagine that it's a terrible hinderance to only be able to zoom into 80' on the Colorado for the average cacher.

Link to comment

Why? When coming near the cache, I use the arrow all the time.

 

Let's not debate this one. It is a personal preference and mine is different than yours. I find it much easier to walk to a point I can see on a map (assuming overzoom is supported) versus using a pointer and a distance on the compass page. I know people who do both, Coke vs. Pepsi. Garmin should support both.

 

GO$Rs

Link to comment

Why? When coming near the cache, I use the arrow all the time.

 

Let's not debate this one. It is a personal preference and mine is different than yours. I find it much easier to walk to a point I can see on a map (assuming overzoom is supported) versus using a pointer and a distance on the compass page. I know people who do both, Coke vs. Pepsi. Garmin should support both.

I'm a compass person myself, but I don't see any reason to artificially limit how far you can zoom in. I'm guessing that if the Colorado zoomed in as far as the 60CSx people would be happy?

Link to comment

.......... I'm guessing that if the Colorado zoomed in as far as the 60CSx people would be happy?

 

NO,absolutely NOT.........reaching that lofty goal is impossible because opinions are too varied as to what is "perfect", and it is obvious that there are a great number of people that absolutely do not understand the difference between a compass and a bearing pointer (or course pointer option).

 

........back to the OP's subject...... that "wandering around" is the result of the higher sensitivity chip. (60 & 76 x series also) It's picking up position "noise" that also is reflected in odometer and speed reading "errors". People complain about that too. However, the same people love the way the new units maintain lock under cover.

 

If you can't understand WHY it's doing WHAT it's doing, and don't like it , then you'll just have to go back to an older unit with the less sensitive chip.

 

I understand that in the "auto archiving" process, the new Colorado "filters out" that "position noise" or wandering around. However, Note that in this forum, there have already been complaints about that too!

Edited by Grasscatcher
Link to comment

I'm not sure it does do that. I've only stated that the Zumo, which has a similar archive function, does filter away limited wandering if it's between activities in the log.

I don't know, but I assume that they've limited the zooming to something that suits the map, as they probably have had too many support calls about the "overzoom" message.

Link to comment

.......... I'm guessing that if the Colorado zoomed in as far as the 60CSx people would be happy?

 

NO,absolutely NOT.........reaching that lofty goal is impossible because opinions are too varied as to what is "perfect", and it is obvious that there are a great number of people that absolutely do not understand the difference between a compass and a bearing pointer (or course pointer option).

 

........back to the OP's subject...... that "wandering around" is the result of the higher sensitivity chip. (60 & 76 x series also) It's picking up position "noise" that also is reflected in odometer and speed reading "errors". People complain about that too. However, the same people love the way the new units maintain lock under cover.

 

If you can't understand WHY it's doing WHAT it's doing, and don't like it , then you'll just have to go back to an older unit with the less sensitive chip.

 

I understand that in the "auto archiving" process, the new Colorado "filters out" that "position noise" or wandering around. However, Note that in this forum, there have already been complaints about that too!

 

OK, fair enough, that makes sense. That was all I was asking. I didn't realize that there was a trade off there. I suppose that's a good trade if it has to do that. Does this also account for its inability to "average" a waypoint?

Link to comment

This has been present in my 60Cx as well. When the unit is in poor reception conditions like indoors or under heavy canopy it would be pronounced. My 300 will record this kind of effect, too in those conditions. And no, SA is not back :rolleyes: .

 

Well, what's your take on the maximum 80' zooming in on the Colorado? I can't believe that a new whizz-bang unit has totally taken a step backwards to this level. Seems as though this is really going to be a terrible hinderance when geocaching?

What in heavens name do you mean?? Surely you do not try to use the map to step on the Geo icon on the screen at a high zoom level?? do you?? I have never done that with all of my finds and 6 years of this - no hindurance to me whatsoever.

Link to comment

OK, fair enough, that makes sense. That was all I was asking. I didn't realize that there was a trade off there. I suppose that's a good trade if it has to do that. Does this also account for its inability to "average" a waypoint?

 

See Apersson's reply above for a clarification....I should have said that the Colorado "may" filter out.....

 

No, I believe that averaging may be a different "problem". In previous models "averaging " has always been a separate step when a waypoint is saved. Unless the Colorado happens to be averaging internally without "advertising it", then IMHO that is a software problem that should definitely be corrected in a future update.

Averaging is definitely needed.

 

Go outside and get a good "lock" , clear the tracklog and then set the unit out in the open where it has good reception for a while....... 30 min or so. Then take it back inside and download that track, zoom way in and you'll see that all that "wandering" is really just within a few meters or feet. If you also previously also reset the odometer, you may also see some goofy max speed. Something like 100-200+ mph or higher. In some of that "position noise" movement, the distance between one trackpoint and the next might only be 1 or 2 or 3 meters but the time it took to "travel" that distance was only maybe 1 sec........really fast "movement".

 

Does that help?

Link to comment

...

OK, fair enough, that makes sense. That was all I was asking. I didn't realize that there was a trade off there. I suppose that's a good trade if it has to do that. Does this also account for its inability to "average" a waypoint?

 

I didn't quote everyone, but I may cover all prior comments. :D

 

I have not seen any reduction in estimated accuracy in months and months. I don't believe SA is in affect. We're not even under a Condition Orange level, are we? Wherever we are, it hasn't changed in some time.

 

I think most people wanted a redesigned GPSmap 60 unit in a flashy new package. AND they wanted it for $1 more than the cost of the 60 CSx!

 

What they got is an opportunity. But that's not good enough! :D

 

I too noticed that the map didn't zoom in past 80 feet. On my first geocache search on the 400t I was frustrated until I realized that I rarely depend on the map to tell me where I am. Using that map is pretty impossible on a smaller scale unless the compass is rock solid as well as the GPS position. When we see the compass page jump from 10 feet to 22 feet, we think little of it, but when the map swings wildly around and your position flails along with it, we forget what we're in the woods looking for.

 

I remember what I was told as a new cacher: When you get close to ground zero, lay your GPS down and start looking for a likely place to hide a cache.

 

Even with this new antenna and a stable electronic compass, it honestly takes 2 - 3 minutes on site to get a legitamate position reading. Until you do get a stable reading, you're really buying a lie. This is true on the map page as well. You're trying to locate this postion on the Earth that may be 20 feet from where you really want to be. Using the map to find this artificial location really doesn't do one much good. Does it?

 

You didn't ask, but my honest reccomendation for you is this:

 

The compass page is a beautiful thing. You can set the four different data fields to tell you almost all you need to find a cache except for the description itself.

 

- Accuracy of GPS

- Battery Level

- Bearing

- Distance to Destination

- GPS signal strength

- Sunset

- Time of Day

 

Plus, you can have the bearing pointer on the compass itself, giving you no real need for a digital bearing (unless you use a compass in addition to your GPS unit.)

 

The map page gives you a relatively blank page, bread crumbs, and minimal information. I don't see how using this really gets you closer to GZ or gives you more information.

Link to comment

This has been present in my 60Cx as well. When the unit is in poor reception conditions like indoors or under heavy canopy it would be pronounced. My 300 will record this kind of effect, too in those conditions. And no, SA is not back :D .

 

Well, what's your take on the maximum 80' zooming in on the Colorado? I can't believe that a new whizz-bang unit has totally taken a step backwards to this level. Seems as though this is really going to be a terrible hinderance when geocaching?

What in heavens name do you mean?? Surely you do not try to use the map to step on the Geo icon on the screen at a high zoom level?? do you?? I have never done that with all of my finds and 6 years of this - no hindurance to me whatsoever.

 

This is how I do it. Are you saying I geocache "wrong"? I agree with g-o cashers that it is a personal preference and Garmin's units (particularly ones that cost $600!!) should allow you to find a cache without using the silly compass if you so desire. The lack of overzoom would definately be a hindrance to many people.

Link to comment

OK, fair enough, that makes sense. That was all I was asking. I didn't realize that there was a trade off there. I suppose that's a good trade if it has to do that. Does this also account for its inability to "average" a waypoint?

 

See Apersson's reply above for a clarification....I should have said that the Colorado "may" filter out.....

 

No, I believe that averaging may be a different "problem". In previous models "averaging " has always been a separate step when a waypoint is saved. Unless the Colorado happens to be averaging internally without "advertising it", then IMHO that is a software problem that should definitely be corrected in a future update.

Averaging is definitely needed.

 

Go outside and get a good "lock" , clear the tracklog and then set the unit out in the open where it has good reception for a while....... 30 min or so. Then take it back inside and download that track, zoom way in and you'll see that all that "wandering" is really just within a few meters or feet. If you also previously also reset the odometer, you may also see some goofy max speed. Something like 100-200+ mph or higher. In some of that "position noise" movement, the distance between one trackpoint and the next might only be 1 or 2 or 3 meters but the time it took to "travel" that distance was only maybe 1 sec........really fast "movement".

 

Does that help?

 

I disagree that the lack of averaging is even an issue.

 

First of all, with the averaged waypoint on the 60 CSx, has anyone really ever seen an averaged waypoint vary by more than 1 unit in either north or south? (by 1 unit I mean +/- .001 minutes.) The new SiRF II antenna is very fast and stable. Even with an estimated accuracy of (say) 20 feet, the waypoint coordinates rarely varied by more than +/- 10 feet total around 80% of the time. Maybe it was determined that "averaging" a waypoint wasn't really any more accurate than getting a good reading and taking a solid measurement.

 

In one way I believe that averaging waypoints is good for geocachers. Most cachers (the ones I have wondered across) rarely take the time to wait for a good satellite lock before they attempt to measure coordinates. Averaging forces them to slow down and take a longer reading, which may or may not actually give a better reading.

 

On the wondering issue: Remember what estimated accuracy of 20 feet really means. Pretend you are standing in the middle of a dart board 40 feet across. You can reasonably say that the coordinates you are measuring are *somewhere* on that dart board. You don't know exactly where. So, if you do as the previous poster says and leaves the unit with a good look at the sky, clear the track log, and let the unit record data for 30 minutes or so, you're going to see a fuzzy ball that sits nicely inside this representation of a 40' wide dart board. Its not that the GPS is wondering. Its taking data based on moving satellites and telling you where it thinks that it is.

 

On the flip side, the averaged waypoint is a real-time moving center of this fuzzy ball. Say "stop" and you've got a pretty good idea of where you are, but still within a smaller fuzzy ball. This center really isn't much closer to any of the data points in the fuzzy ball.

 

I think a lot of the reduced functions on this unit, including the reduced brightness of the display (which is bigger and will eat up more power than the smaller display of the 60 CS(x) units, is an attempt at keeping the battery life to a reasonable level.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...