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Static Navigation on GlobalSat BT-359 and Garmin GPSMap 60CSx
GadgetGirl
Does setting the Garmin GPSMap 60CSx to "Pedestrian" disable static navigation?

Is static navigation enabled by default on the GlobalSat BT-359?

Both have SirfStar III chipset.
Ken in Regina
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Originally Posted by GadgetGirl
Does setting the Garmin GPSMap 60CSx to "Pedestrian" disable static navigation?
It might. Or it might simply modify the algorithm used to reduce the effects of multipathing so that it accepts indication of smaller/slower movements better rather than rejecting them.

What happens when you set it to Pedestrian and go for a walk? What happens if you change it back to Car/truck and walk with it?

Quote:
Is static navigation enabled by default on the GlobalSat BT-359?
What happens to the position display when you hook it up to, say, Mobile PC? If you are sitting in the same position is the vehicle icon stable? Or is it moving around and showing small position and direction changes?

...ken...
GadgetGirl
After I got home and looked at the settings more closely on the Garmin, I realized the Pedestrian settings were listed under the Routing options, so I don't think it has anything to do with Static Navigation. But I do think the unit has SN disabled for two reasons:
1. If I zoom in and start walking out the door and to the driveway, it almost instantly updates. This makes sense as it is a handheld and primarily used for hiking.
2. We were in Spokane a few weeks ago and I was navigating to a coffee shop. Unable to find a close parking spot, we stopped several blocks from our destination. Once we stopped Streets & Trips started behaving eratically not showing quite the correct location and the map was not oriented correctly. OCD as I am, I wanted to determine if this was caused by stopping or deflection of signals (we weren't that near tall buildings). As soon as we were moving again the screen straightened out.
Am I correct in my thinking?

The GlobalSat I believe also doesn't have SN enabled. Not sure. When I sit still the position display DOES move around a bit in S&T, so I got brave and enabled it in SirfDemo. The icon now is stable while motionless, but moves appropriately when I drive.

I got interested in this when I had the Spokane problem.

When I first got the Garmin GPSMap, I tested it on a local trail. The trail was in the open, not forested, with a lake on one side (clear view of the sky) and a cliff wall about 100 ft away. The unit showed the lake on the wrong side of me! That was very confusing! Do you think the cliff deflected the signals even though I had clear views of a lot of sky? Here is a topo map of the trail:
Attached Images
topomap.jpg  
Ken in Regina
Hi Karen,

I deleted your second post as it was an exact duplicate and did not have the topo image attached.

Re: your example of The Cliff and The Lake (sounds like the title of a cheap romance or mystery novel). Two possibilities. One is strong multipath from the cliff.

The other possibility is that the lake is in the wrong location on the map.

It looks like that cliff is pretty steep and high. With the lake and the cliff you have a perfect situation for strong multipath.

The cliff will completely block signals from perhaps 30% or more of the sky so the signals hitting your location would be only from the area that is not blocked by the cliff. It's already a bit of a lopsided picture. But it gets worse.

The cliff will reflect both the primary signals and the reflections from the water.

The water will reflect both the primary signals and the reflections from the cliff.

And so on.....

So your situation was a perfect storm for multipath to pretty much overwhelm the receiver.

As you have probably determined from your research, "static navigation" is nothing more than some calculations that attempt to eliminate "movement" resulting from multipath (reflected) signals rather than the true direct signals from the satellites.

Any time you see movement of the location indicator icon on the map or reorienting of the map to show a direction change when you are in fact motionless, that's an indication that the GPS receiver is reporting movement that is not happening. That is a result of multiple factors, but primarily of multipath signals fooling the receiver.

Some people find that annoying in automobile navigation systems. They think that when the car is stopped the map display should also stop moving. "Static navigation" was introduced to help deal with that situation.

But it has a couple of downsides. One is that it introduces some delay in processing the incoming signals and reporting the "next" position to the map display. In testing we've done in another discussion we have determined that delay to be anywhere from one or two seconds to as high as four or five seconds.

Another is that it's nearly impossible to use a receiver with static navigation for hiking, unless you can hike steadily at faster than 5 mph. (!)

Some of the newer handhelds actually take advantage of multipath to get a decent approximation in situations where the primary signals aren't available. My Legend HCx can get a decent lock in my basement office. So will the iTrek M7. There is a lot of metal ductwork in the way, so there is no way that primary signals are getting down here. Without the ability to take advantage of multipath reflections, it would be impossible to get any useful information down here.

As you said, it makes sense that your GPS60Csx does not have static navigation enabled. It would make it a horrid handheld GPS. It would be pretty much useless.

If you need a solid location for future reference, check and see if your 60 has an averaging function. My Legend HCx has an averaging selection when I create a waypoint so that it will average the readings over a period of time to get the most accurate location. If I want a fairly accurate location for a waypoint I let it average for at least thirty seconds before locking in the waypoint. If I'm in no rush I'll set the Legend to average the location, set in on the spot I'm marking and walk away from it for a few minutes.

I've never much worried about static navigation because I understand the cause of the spurious "movement" on the map display and it doesn't bother me. So I've never paid any attention to which devices might have it enabled by default, or if they even have the capability at all. I mostly don't care. And if I had to make a choice I would leave it disabled permanently on any of my devices.

For the record, based on the behaviour of the devices I own I would say that all of these devices do not have it enabled (or don't have it at all):

iTrek M7
Garmin GPS10x
Globalsat BU-353
Pharos 500 (older Streets&Trips)
Navation 168 (newer Streets&Trips Ublox)
eTrex Legend HCx

This is not based on any technical knowledge. It's based simply on personal observation. All of them will allow the position to "move" around when at a dead standstill.

....What a longwinded way to not answer your questions. I shoulda been a politician! :rofl"

...ken...
GadgetGirl
Sorry about the 2 posts. I read and post while I'm at work (night shift). I must have been interrupted and didn't realize I posted the first time.

After reading your post (and it wasn't long-winded at all), I realize all of the problems were probably caused by lakes, cliffs, and tall buildings. I didn't think about a lake causing reflections.

I've never been bothered by the small movements of the icon when stationary. I actually like to see it doing something, if that makes any sense. I realize civilian GPS is not pinpoint accurate. What really bothers me is the map turning upside down or sideways! My concern was that in dense metropolitan areas, a GPS nav app can actually "snap" to the wrong road.
I'm not going to "fiddle" with the Garmin GPSMap, but I am having fun with the $18 used GlobalSat and SiRFDemo. (Haven't "bricked" it yet!)

The Garmin does have an averaging feature, but I've never had the need to be that accurate. Now, if I was in the Bob Marshall Wilderness that might be a different story!

Oh, and BTW, you don't sound like a politician at all as I actually understood what you said! Are Canadian politicians as bad as American ones?
Marvin Hlavac
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What really bothers me is the map turning upside down or sideways!
When ever I find myself in between tall buildings, I turn off 3D-view mode & map rotation, and I switch to 2D & North Up. That way, when the signal is bad, my position on the map may be jumping up and down, left and right, but at least the map is not spinning and turning.

Quote:
I am having fun with the $18 used GlobalSat and SiRFDemo. (Haven't "bricked" it yet!)
Certain features of Sirf Demo may make your GPS unusable if Sirf Demo is used while the GPS is connected via Bluetooth (as opposed to via USB), but you already know how to reset your GPS to factory settings. Just remove the battery for a few hours, and all will be back to normal.
GadgetGirl
Hmmm.....I can't remember if I had 3D on or not. Will experiment on next trip to Spokane. This was very disconcerting as we had to park a few blocks from the coffee shop and I wanted to look at the map to see where we needed to walk. Of course, all of this seems rather ridiculous in light of the fact that just a few years ago civilians didn't even have decent GPS! Using a paper map ranks right up there with only getting 3 channels on broadcast TV! My, how fast we get used to these "modern conveniences"! (I used a slide rule in high school - oops, just gave away my age! )

Thanks for the tip about BT and SiRFDemo. Didn't know that. Heven't actually changed anything, except SN. Just looking around and trying to figure it out!
Ken in Regina
Quote:
Originally Posted by GadgetGirl
Oh, and BTW, you don't sound like a politician at all as I actually understood what you said!
That's a relief!

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Are Canadian politicians as bad as American ones?
Probably. All they're interested in is what's best for getting them the most campaign funds and what will get them re-elected, not what's best for the country, province or city.

...ken...
GadgetGirl
Quote:
Probably. All they're interested in is what's best for getting them the most campaign funds and what will get them re-elected, not what's best for the country, province or city.
What always amazes me (and corporate CEO's do the same thing) is how they can talk for 30 min and never say anything! How do they do that? Of course, my husband would tell you that I do that quite well all the time.
Ken in Regina
Quote:
Originally Posted by GadgetGirl
What always amazes me (and corporate CEO's do the same thing) is how they can talk for 30 min and never say anything! How do they do that? Of course, my husband would tell you that I do that quite well all the time.
He must know my wife.

...ken...
GadgetGirl
:rofl"

Mike says I can have a conversation with a fencepost!
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