Static Navigation Effect on GPS Software Question

neoshi · Occasional Visitor Joined: May 16, 2007 Posts: 7

Hi all,

I've been wondering about the MTK static navigation issue though. Does it have any substantial effect on GPS software (i.e. Route 66) in that it will cause your software to assume you are still moving/somewhere else and therefore affect your turn-by-turn directions? The reason I ask is that while I see the tracks that MTK chipsets have been drawing under the numerous logs posted, I have yet to see a demonstration of whether or not they could potentially cause someone to go around in circles while walking around in a city with tall buildings (i.e. namely Tokyo or New York) or have a wrong fix (i.e. assume I am three blocks ahead and cause me to turn early even though the street name doesn't match).

Your answers would be greatly appreciated. Thank you.

neoshi · Occasional Visitor Joined: May 16, 2007 Posts: 7

perhaps this belongs in the advanced lounge? doesn't seem to gather a response here. Crying or Very sad

Skippy · Posted: Sun Sep 16, 2007 8:56 am Post subject:

Hi and

I don't have specific experience with the MTK GPS but my experience of SiRF chipsets is that you need to switch static navigation off when walking.

In a car, you move fast and decisively in one direction so static navigation works. But walking you tend to move in fairly random directions at a slow speed so with static navigation your position will only update every 20-30 meters which makes the GPS pretty much useless.

In "urban canyons" where you don't have a good reception is quite a different story. The problem here is that your position can be 20 to 50 meters (or more) adrift from reality. You have to be very aware of what sort of fix you have and figure out when your unit is confused and when it's giving good information.

Bottom line recommendation: SN OFF for walking, ON for driving. I just leave it Off all the time though and the occasional jittering of position doesn't bother me...
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Gone fishing!

neoshi · Occasional Visitor Joined: May 16, 2007 Posts: 7

Thanks Skippy!

The problem is I've only had experience with all-in-one solutions (i.e. Garmin Nuvi) where they pretty accurately depict my positions and give a decent amount of time and warning before you actually need to turn.

I'm worried that with SN on, the GPS will think I'm 50m ahead (especially if I'm stopped at a traffic light) and will proceed to depict that I am moving and approaching an intersection where I need to turn, make decision, etc. I suppose I will have to go ahead and try it for myself.

I don't plan on using the GPS much for walking and even if I do, I don't have software on my PDA to actually depict it without data plan requirements (any suggestions here?) So, as long as I stick to the streets, I think an MTK chipset will be just fine.

I've been considering SiRFIII receivers but the most recent developments seem to be all MTK receivers. But I'll have to think about it a little while longer to decide on a decent SiRFIII BT receiver if I decide to skip the MTKs. In addition, I don't know of any SiRFIIIs that have an on-the-fly method of switching SN off. As far as I know, I have to switch it off via commands through a computer and that doesn't make a car to foot transition easy.

philpugh · Posted: Sun Sep 16, 2007 10:04 pm Post subject:

In my opinion it's not worth worrying about turning SN on when in a car. So what if you get a small amount of position wandering - it's not going to affect things. PND for cars already 'manipulate' the calculated GPS position to place you on the road in any case
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Phil

robertn · Frequent Visitor Joined: Feb 06, 2005 Posts: 564

These devices are tools that aid your navigation. Only a fool would rely solely on GPS - as more than a few marineers have found out in the past.
we should all take a lesson from our salty cousins......

neoshi · Occasional Visitor Joined: May 16, 2007 Posts: 7

The problem here is that SN is ALWAYS ON in MTK chipsets. I believe THAT, in itself, creates potential issues with navigation. But of course, there is always some sort of "correction" done by the software counterpart, so I believe, from what I've heard thus far, is that despite SN having wandering issues in MTK chipsets, it will not present itself as a problem when coupled with navigation software.

Charting my walks is only an issue when I go hiking, where there are no streets, but landmarks will always be my key in such a case.

Thanks guys.

philpugh · Posted: Mon Sep 17, 2007 9:46 am Post subject:

neoshi · Occasional Visitor Joined: May 16, 2007 Posts: 7

Shortsighted indeed. Most of the recent MTK-based receivers are coming out of Taiwan and Hong Kong though, where (from personal experience) we don't walk much. That probably explains why there has been no need for providing an "off button" for SN.

I think I'll just give the MTK receivers a try anyhow. SiRFIII receivers with equivalent capabilities seem to cost $30-50 more.

Skippy · Posted: Mon Sep 17, 2007 9:34 pm Post subject:

neoshi · Occasional Visitor Joined: May 16, 2007 Posts: 7

Yeah. Luckily, I don't think it's as big of a problem as multipath errors. Sucks when you're on Market Street and the GPS thinks you're on Broadway... Mad

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