Iguidance + Refresh issue

Tennis_Monk · 12-24-05, 08:05 PM

While using I guidance, even at normal driving speeds i see that the map representation is significantly behind the actual location of the vehicle.

Eg: It will show that i am at the junction after i have successfully made a turn and already into the street for a few yards.

I checked the baud rate and it is at 38400. I have axim 51v so i dont think it is a processor speed issue.

Anybody have similar experiences or am i missing some setting?

AximTT · 12-24-05, 10:22 PM

What kind of GPS receiver are you using?

Tennis_Monk · 12-25-05, 12:17 AM

Axim 51v + bt-338.

AximTT · 12-25-05, 12:45 AM

I have Axim X50v upgraded to WM5 and BT-338. I did not observe similar problem.

Tennis_Monk · 12-25-05, 06:51 AM

Only other aspect i can think of is, application is installed on a CF card. This is from Sandisk and i brought it on a sale during thanksgiving.I got it for 9$. May be it is slow. Not sure.

AximTT · 12-25-05, 09:03 AM

Try to install a small map on RAM and you can determine if it's a memory issue.

Or to check if it's a softwre issue, you can try demo version of Mapopolis. It's free.

Tennis_Monk · 12-25-05, 12:36 PM

I will try the RAM option. I can demo Mapopolis but i wont be able to afford it after trial period (already burnt a lot of money on Iguidance).

JakeRich · 12-25-05, 06:22 PM

It should normally lag about 1 second, maybe a bit more, behind your real position. That's part of the design of GPS overall.

gov · 12-26-05, 08:36 PM

Originally Posted by Tennis_Monk

While using I guidance, even at normal driving speeds i see that the map representation is significantly behind the actual location of the vehicle.

Eg: It will show that i am at the junction after i have successfully made a turn and already into the street for a few yards.

I checked the baud rate and it is at 38400. I have axim 51v so i dont think it is a processor speed issue.

Anybody have similar experiences or am i missing some setting?

I just got my system and i'm noticing the same thing. it was not a huge deal for me since i was going kinda slow and saw on the map that it was time to make the turn, but i could see this being a problem if i was unfamiliar with the area, and driving faster than say 20 mph.

anyone have any ideas???

btw--i have mine installed on a 51v on my sandisk ultra cf card--speed here should NOT be an issue.

JakeRich · 12-26-05, 09:22 PM

The system gives plenty of advanced warning of upcoming turns. You can glance at the display to see where it wants you to go. The minor delays in display updates (typically about a second or so) should not be a problem, even in unfamiliar areas. NO GPS System will be able to be closer than about 1 second or so. All receivers update your location once per second, so the applications get that update and have to do the calculations for how to display, etc, adding a few microseconds. With WM5 you also have the processing of the GPS port handling adding a few microseconds. As I said, the delay should be on the order of 1 second. at 20 mph, you are travelling about 30 feet per second, so an error of 10 yards is about right at that speed. In addition to that error, there are map errors in where roads are displayed. See the GPS201 link in my sig for pictures and explanations.

dougsnell · 12-27-05, 03:14 PM

Originally Posted by JakeRich

It should normally lag about 1 second, maybe a bit more, behind your real position. That's part of the design of GPS overall.

The only other time I've noticed a lag is when I'm drastically braking or accelerating. Particularly when braking, the software will often "estimate" my speed, and tell me to turn before I actually reach a red light. Then it gets weirded out because it thinks I turned, and it doesn't want to repeat directions for some odd reason. It figures it out once I really do make the turn, but it appears to be setting me up for a U-turn of some kind.

I've noticed the reverse situation when accelerating (say, stopped on an off-ramp several cars back, and accelerating through the turn ... it tells me to turn after I've already turned).

JakeRich · 12-27-05, 04:34 PM

dougsnell, you didn't say what software you use, but TT and OCN5 both do "predictive" screen updates to make them look more responsive. They predict from your last fix and direction/speed where they think you will be and update the screen 4-5 times each second instead of just once. Unfortunately, that prediction process breaks down when you turn, start or stop.

Tennis_Monk · 12-27-05, 04:46 PM

Originally Posted by JakeRich

dougsnell, you didn't say what software you use, but TT and OCN5 both do "predictive" screen updates to make them look more responsive. They predict from your last fix and direction/speed where they think you will be and update the screen 4-5 times each second instead of just once. Unfortunately, that prediction process breaks down when you turn, start or stop.

I see another issue (may be with other software's as well).
When i turn into a Shopping complex which runs directly Parallel to the street (aka a street with lot of shops and has their own parking away from street) , Iguidance thinks I am still on the street(even though i am clearly good 40-50 ft away from street) and i guess it uses SNAP to Street function of etc.

The Refresh issue is certainly annoying especially when there are Immediate turns in very short time. I tried running a few tests myself at various speeds and it doesnt seem to make any difference to screen refresh unless i drive under 10miles per hour.I even tinkered with Baud rate (now at 118K something) and that doesnt help either. Removed all programs except Iguidance from memory -->No help either. The lag is more than 4-5 seconds ( i will run a few more conclusive tests to get a accurate number).

Where i live (Connecticut), i am very familiar with the entire area and GPS refresh is no biggie. When i drive into NY City next weekend, then will be real test!!

dougsnell · 12-27-05, 10:52 PM

Originally Posted by JakeRich

dougsnell, you didn't say what software you use, but TT and OCN5 both do "predictive" screen updates to make them look more responsive. They predict from your last fix and direction/speed where they think you will be and update the screen 4-5 times each second instead of just once. Unfortunately, that prediction process breaks down when you turn, start or stop.

I use iGuidance, and wouldn't trade it for another package.

I don't know enough about the inner-workings of the software (never cared enough outside what I can reasonably ascertain), but I've had enough experience with it to know it has some kind of predictive analysis because it makes occasional mistakes (like thinking I've turned when I simply stopped quickly a few feet from the turn). That's about my only nit-pick with it, but I suspect anyone who's that picky should go looking for another technology ;)

JakeRich · 12-27-05, 11:09 PM

Originally Posted by Tennis_Monk

I see another issue (may be with other software's as well).
When i turn into a Shopping complex which runs directly Parallel to the street (aka a street with lot of shops and has their own parking away from street) , Iguidance thinks I am still on the street(even though i am clearly good 40-50 ft away from street) and i guess it uses SNAP to Street function of etc.

The Refresh issue is certainly annoying especially when there are Immediate turns in very short time. I tried running a few tests myself at various speeds and it doesnt seem to make any difference to screen refresh unless i drive under 10miles per hour.I even tinkered with Baud rate (now at 118K something) and that doesnt help either. Removed all programs except Iguidance from memory -->No help either. The lag is more than 4-5 seconds ( i will run a few more conclusive tests to get a accurate number).

Where i live (Connecticut), i am very familiar with the entire area and GPS refresh is no biggie. When i drive into NY City next weekend, then will be real test!!

Baud rate makes NO difference. See GPS201 for that discussion.