GPS issues

Pie Pants · 07-26-2005

Now I've searched the forums already, and my GPS issues don't seem to be documented anywhere else. I bought a cheap "puck" serial-port GPS off eBay. It uses the SiRF-II chipset, and outputs via the NMEA protocol. Works happily in HyperTerminal and an unlocked copy of Garmin's MapSource software in NMEA mode. Also works fine under Linux with Kismet and GPSDrive.

Now when I set it up in NetStumbler, it works fine for about 2 minutes. After this, NetStumbler just says "GPS: Timed out." I have to restart NetStumbler for it to get a value off the GPS again. Even then, if it times out and I save the open file in NS, restart NS and open the file I just had open, then restart scanning, NS will not write any of the GPS data to the file, even though it's getting data from the GPS.

I'm lost as to why it works fine in four completely different programs, then NetStumbler times out. Any help would be greatly appreciated.

Thorn · 07-26-2005

You're probably loosing the signal. Typically, you get a timeout like that when the GPS signal is gone.

streaker69 · 07-26-2005

Quote:

Originally Posted by Pie Pants

Now I've searched the forums already, and my GPS issues don't seem to be documented anywhere else. I bought a cheap "puck" serial-port GPS off eBay. It uses the SiRF-II chipset, and outputs via the NMEA protocol. Works happily in HyperTerminal and an unlocked copy of Garmin's MapSource software in NMEA mode. Also works fine under Linux with Kismet and GPSDrive.

Now when I set it up in NetStumbler, it works fine for about 2 minutes. After this, NetStumbler just says "GPS: Timed out." I have to restart NetStumbler for it to get a value off the GPS again. Even then, if it times out and I save the open file in NS, restart NS and open the file I just had open, then restart scanning, NS will not write any of the GPS data to the file, even though it's getting data from the GPS.

I'm lost as to why it works fine in four completely different programs, then NetStumbler times out. Any help would be greatly appreciated.

Two Questions:

1. Are you attempting to use the GPS with NS at the same time another program is using the GPS?

B. What are your settings for the GPS? Try setting them to 2400,8,n,1.

Pie Pants · 07-26-2005

Quote:

Originally Posted by Thorn

You're probably loosing the signal. Typically, you get a timeout like that when the GPS signal is gone.

I didn't think this was the case (it'll sometimes happen when I'm sitting still), but if it is, how can I get around this?

Quote:

Originally Posted by streaker69

Two Questions:

1. Are you attempting to use the GPS with NS at the same time another program is using the GPS?

Nope. Just NetStumbler. I'm aware that I need a program to share the GPS data if I want to run 2 programs at the same time.

Quote:

Originally Posted by streaker69

B. What are your settings for the GPS? Try setting them to 2400,8,n,1.

The settings are NMEA 0183, COM1, 4800, 8, None, 1 as described in the documentation that came with the GPS, but I can try 2400 later today, see if that helps.

streaker69 · 07-26-2005

Quote:

Originally Posted by Pie Pants

I didn't think this was the case (it'll sometimes happen when I'm sitting still), but if it is, how can I get around this?

Nope. Just NetStumbler. I'm aware that I need a program to share the GPS data if I want to run 2 programs at the same time.

The settings are NMEA 0183, COM1, 4800, 8, None, 1 as described in the documentation that came with the GPS, but I can try 2400 later today, see if that helps.

Sounds like your GPS is just a POS.

Thorn · 07-26-2005

Quote:

Originally Posted by Pie Pants

I didn't think this was the case (it'll sometimes happen when I'm sitting still), but if it is, how can I get around this?

Move the GPS to the dashboard or someplace it has good sky view. The car roof works well for some GPS units.

Pie Pants · 07-26-2005

Quote:

Originally Posted by Thorn

Move the GPS to the dashboard or someplace it has good sky view. The car roof works well for some GPS units.

It was in the rear window of the car, it had a pretty decent view of the sky.

Just an idea, would piping the GPS data through GpsGate help at all?

Thorn · 07-26-2005

Quote:

Originally Posted by Pie Pants

It was in the rear window of the car, it had a pretty decent view of the sky.

Just an idea, would piping the GPS data through GpsGate help at all?

Probably not.

streaker69 · 07-26-2005

Quote:

Originally Posted by Pie Pants

It was in the rear window of the car, it had a pretty decent view of the sky.

Just an idea, would piping the GPS data through GpsGate help at all?

How is your GPS powered? Is it pulling power directly from the serial port or does it have PS/2 connector to draw power from?

Pie Pants · 07-26-2005

It's powered through the PS/2 port.

Doesn't matter though, it appears GpsGate was the solution after all. Took the laptop out the back, acquired a signal, fired up NS, then deliberately lost and re-acquired the signal, and NS continued to display coordinates. A quick export of the NS data to a text file supports this.

beakmyn · 07-27-2005

I think what is happening is Netstumbler is not polling the unit fast enough so the device is going to sleep.

Starpoint · 07-27-2005

Quote:

Originally Posted by beakmyn

I think what is happening is Netstumbler is not polling the unit fast enough so the device is going to sleep.

I have my mini stumbler and netstumbler set to scan according to GPS speed. I do not know if that will fix the issue, but in order for NS to know what speed to poll at, it has to keep getting speed updates from the GPS..

other than that I would scout around for a normal GPS and get the appropriate cables.

Pie Pants · 07-27-2005

Quote:

Originally Posted by Starpoint

other than that I would scout around for a normal GPS and get the appropriate cables.

I plan on doing that sometime. But for now, this is working surprisingly well. I've written a basic PHP script to parse NetStumbler's output, locate the strongest point of each AP, then give a link to the location of the strongest signal through MSN Maps & Directions. For an AU$100 GPS reciever, it's pretty damn accurate - the points I picked up on the way home from work have been spot on where they should be.

Starpoint · 07-27-2005

Quote:

Originally Posted by Pie Pants

I plan on doing that sometime. But for now, this is working surprisingly well. I've written a basic PHP script to parse NetStumbler's output, locate the strongest point of each AP, then give a link to the location of the strongest signal through MSN Maps & Directions. For an AU$100 GPS reciever, it's pretty damn accurate - the points I picked up on the way home from work have been spot on where they should be.

I use a Magellan GPS with a 128 SD card in it for maps, it has WAAS and NMEA V2.1GSA and it works VERY well.

07-26-2005	#1 (permalink)
Pie Pants Registered Member Join Date: May 2005 Posts: 17	GPS issues Now I've searched the forums already, and my GPS issues don't seem to be documented anywhere else. I bought a cheap "puck" serial-port GPS off eBay. It uses the SiRF-II chipset, and outputs via the NMEA protocol. Works happily in HyperTerminal and an unlocked copy of Garmin's MapSource software in NMEA mode. Also works fine under Linux with Kismet and GPSDrive. Now when I set it up in NetStumbler, it works fine for about 2 minutes. After this, NetStumbler just says "GPS: Timed out." I have to restart NetStumbler for it to get a value off the GPS again. Even then, if it times out and I save the open file in NS, restart NS and open the file I just had open, then restart scanning, NS will not write any of the GPS data to the file, even though it's getting data from the GPS. I'm lost as to why it works fine in four completely different programs, then NetStumbler times out. Any help would be greatly appreciated.

07-26-2005	#2 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,098	You're probably loosing the signal. Typically, you get a timeout like that when the GPS signal is gone. __________________ Thorn "I'm The Doctor. I'm a Time Lord. I am from the planet Gallifrey in the constellation Kasterborous. I'm 903 years old and I am the man who is going to save your lives and all 6 billion people on the planet below... You got a problem with that?"

07-27-2005	#11 (permalink)
beakmyn root\.workspace\.garbage. Join Date: Aug 2003 Posts: 4,805	I think what is happening is Netstumbler is not polling the unit fast enough so the device is going to sleep. __________________ Daughter with arms inside shirt: "Daddy I'm not Armish" ┌──────────────────────────────┐ ╞ NS Icons Explained\|et hoc genus omne ╡ └──────────────────────────────┘

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

07-26-2005	#10 (permalink)
Pie Pants Registered Member Join Date: May 2005 Posts: 17	It's powered through the PS/2 port. Doesn't matter though, it appears GpsGate was the solution after all. Took the laptop out the back, acquired a signal, fired up NS, then deliberately lost and re-acquired the signal, and NS continued to display coordinates. A quick export of the NS data to a text file supports this.