Tuesday, December 27, 2005

Navizon: GPS without it

The concept in theory is pretty amazing. GPS where you usually can't have it. For that Navizon counts on information shared and uploaded by its own users with location data of Access Points obtained thru GPS devices with wireless capabilities.

[Update Sept 07: Navizon added cell tower location data to their database. This could be the best shot for current iPhone hackers, I mean users.]

Navizon is not the first effort to make use of GPS to map wireless hotspots Wigle has been doing it for a while and compiled a pretty large database of wireless hotspots, but Navizon is the first that tries to use them to "map the landscape".

Start by creating an account at www.navizon.com, define your local area/home by drawing a rectangle over an area on Google Maps. Make it reasonably small since you will need to download data from the whole area while syncing with the Navizon server.

Download & install the Navizon client to your PocketPC PDA (or Symbian equipped device). Then set up your username and password for your account and configure the settings for your GPS.

Yep, there is quite some work to be done to get started. If you have a GSM phone you can use it instead of a wireless-equipped PDA. You also have the choice to disable those popup's that inform when a wireless network is available, but you will need to soft reset the PDA if you decide to re-enable the popup's.


Now for example, you turn wireless on and plug your GPS card, walk around the neighborhood and start collecting data about the existing access points in your area. If everything goes as planned, you will obtain a fix with the GPS receiver and will be able to see how many access points were found along the way.

That will cause Navizon to store the precise location data obtained thru your GPS device of those AP's. When you get a working connection to an open hotspot you can upload the session data to the Navizon server. That will also cause the download of data from their server for your selected area.

The idea here is that if you live in a metropolis like NY (from where the Navizon folks spread their goods) or downtown SF where GPS doesn't work that reliably you can use Navizon as a software-based GPS using the AP location data as geographic references. This way you can use wireless for navigation (or GSM, based on the location of cell towers). Pretty neat concept. In fact, Intel is also playing with the idea.

Navigating through Access Points

Now that you have a reasonable amount of information about a given area, you can setup Navizon to use that data instead of your GPS receiver. Check the configuration dialog in Navizon for the output port. There you can set a virtual COM port for your GPS software to read the output from Navizon data.

That's where the magic happens: instead of reading NMEA data from the COM port where your GPS receiver is usually connected to, you set Navizon with "No GPS" and its output port to an available virtual COM port, COM4 for example. Now configure your GPS software like GPSDash, PocketTopo and anything else to open the GPS receiver on that same COM4 and voila. You got GPS without it.

In practice you might run into issues where contention between the apps might freeze your PDA or some pretty erratic behavior where the location on your map might zigzag between points without much logic. According to Navizon's FAQ, the more information you obtain around a given area, the more precise its behavior will become.

POI Data

Navizon provides a search tab where you can invoke a search on Google Local with your current location. The same with the PDA-based maps from MapQuest. From the results obtained from Google Local you can zoom into the map image to check where is the closest pizza or coffee shop around. But for that you will need to be close to an open hotspot.

Back to the Navizon website you can check on a Google Map which data you have provided, the coverage in your area (green for open ap's and red ballons for closed ones) and manage a buddy list to share your location among a group of friends, similar to what Mologogo is doing with Java-based phones and PDA's.

If you don't want to share your information, you can use Navizon Solo ($19.99) but you won't have access to the information shared through their webserver either. On the other hand, if you are really into sharing you can also upload log files generated by applications like NetStumbler and WiFiFoFun.

Using it

Navizon uses Frason Virtual Com ports to simulate 4 satellites for GPS-enabled apps. It puts them 90 degrees apart and it does work but in an erratic fashion. Somehow the Toshiba e755 died after trying it for a while. My guess is that you need to have it charged above 75% to have it running smoothly. I got PocketTopo and GpsDash to pinpoint my exact location on a map but it would switch position frequently not sure exactly why. I can't say it was a smooth transition to have the Wireless Positioning converted into map coordinates. At least not visually.

Navizon also has to work some of its kinks when you try to start it up. Sometimes it will say that you don't have wireless on when in fact you do, but this might be related to the Toshiba chip itself and PPC 2003. Others times it will take quite a while to switch between Wireless navigation and GPS when you do have coordinates available for it.

But somehow I got to track more than a hundred AP's and when I was close to an open AP, able to upload them to their server. Notice that you will only be able to use its search features when a wireless connection is available, otherwise you will only be grabbing data. This is similar to the usage of A2B's Navio. If you leave in a big city it might be easy to track an open AP and a GPS fix simultaneously, otherwise it might be a tough game to follow. But the whole concept and implementation are quite amazing. Many kudos.


Sam Critchley said...

Hi. Once again thanks for mentioning A2B in this post!

Intel has been steering an open-source project, called PlaceLab, which works in a similar way to Navizon. A2B has had a PlaceLab-compatible search page running for a while and it seems to work pretty well. The small-screen optimised version is here.

You can find out more and download the PlaceLab apps here. A2B has Symbian Series 60 package here as the proxy code hasn't made it into the main release yet.

Hope that's interesting!

Brad Thompson said...


Now that this works on the iPhone, it's starting to look like location-based services could be on the cusp of taking off.

What we need to see is true GPS-derived location data...then the reliability obstacles will be cleared and the really interesting social networking applications become possible.

Here's a glimpse of what could come next: