How to: Scan for WiFi & Map with GPS (Garmin Nuvi)

In this tutorial, I will be showing you how to connect your Garmin Nuvi to your PC, use its GPS capabilities to view any location in real-time, and combine this functionality with Network Stumbler to scan for WiFi networks and record their geographic location. Later, we will use this data to create a map of our findings.

Even though this guide is specific to the Garmin Nuvi, the same can be accomplished with many other GPS units! Connecting to the PC might require a different procedure, but the Network Stumbler steps will be similar if not exactly the same.

Background Information:

For those curious about why such a roundabout method of connection is used, read the following. It's not required to know for this guide but rather interesting I think.

As you might be aware, the most common and accepted standard for recording GPS data is known as NMEA 0183. Nearly all GPS units abide by this standard, and it is the only accepted format in most mapping software.

There are two problems…

1. The Garmin Nuvi uses a proprietary data format which is not NMEA 0183. This means most PC software can’t read the GPS data it exports.
2. NMEA 0183 data (in most cases) can only be transferred over a Serial interface. New laptops don’t have Serial Ports anymore and the Nuvi only has a Mini-USB plug.
   

So, this is why we will be using GpsGate, a Serial Port emulator and Garmin format converter.

Required Hardware and Software:

1. A Garmin GPS, I am using my Nuvi 760.
2. A Laptop / Netbook or any type of portable Windows PC.
3. A Mini-USB cable
4. Network Stumbler - version 0.40 Download
5. Franson GpsGate: version 2.6 (Trial) Download

Download and install both of these programs. Network Stumbler is 100% free and Franson offers a 2 week free trial of GpsGate. I ended up purchasing the “Express” version of GpsGate for $12.95, a small price to pay for what it delivers.

General Steps:
This is an overview, each step will explained in great detail.

1. Put Nuvi in GPS Mode
2. Install Nuvi as a GPS on Windows
3. Configure GpsGate
4. Configure Network Stumbler
5. Wardrive!

Putting the Nuvi into GPS Mode:

1. Power on the Nuvi as you normally would, but DO NOT plug in the USB cable yet!
2. Press and hold the Battery Icon for about 7 seconds.
   
3. A page with lots of information will appear, a type of Service Menu. Now connect the USB cable. (If you plug the Nuvi in to the computer before reaching this page, it will be read as a storage device instead of a GPS.)
4. Press “Exit”. The Nuvi reboot into GPS Mode and display the Logo screen.
   

Installing the Nuvi as a GPS:

1. Once connected via USB, Windows will run the “Found New Hardware Wizard”. If prompted about Windows Update just select “No, not this time” and continue.
2. On the next screen select “Install the software automatically”.
   
3. Let the Wizard search for and install the "Garmin USB GPS Driver". The process is automated and you will see similar pages to these.
   
   
   
4. At this point the Nuvi should be displaying the Garmin Logo and the driver should be successfully installed.
   
   

Configuring GpsGate:

1. Set the Nuvi aside but leave it plugged in.
2. Launch GpsGate, you will be greeted with a Setup Wizard.
   
3. Check only the first box, “Search for Garmin USB devices”. Make sure the Nuvi is still on and plugged in. Click Next.
4. GpsGate should discover the Nuvi and you will be prompted whether or not to use the found device. You do.
   
   
5. Now that the input has been set, you will be prompted to select an output. For this project, check only the middle box, “I want to share my GPS between several applications”.
   
6. On the next page, you will be presented with a list the Emulated COM Ports. Remember one of the Port Numbers as you will need it later.
   
7. GpsGate is now configured! Right click on the tray icon and select settings. A green icon and the message “Running OK!” signify a successful setup. X-out of GpsGate, it will be sent to the system tray and continue to run in the background.
   
   

Configuring Network Stumbler:

1. Launch Network Stumbler. Since WiFi scanning is enabled by default, you will be bombarded with a barrage of sounds and flashing icons. Take a few minutes to get acquainted with the interface. The play button starts / stops scanning and color represents signal strength. If your wireless card is supported (hopefully it is), networks should start showing up as they are discovered.
   
2. Head on up to the “View” menu, and select “Options”.
   
3. On the General tab, check the box under Scan Speed to “Auto adjust using GPS” and the first 3 boxes on the right.
   
   
4. On the “Display” tab, you can select your choice of units. I prefer degrees, minutes, seconds mode, (d°m’s”) but you might rather display the Latitude and Longitude as decimal values. For this choose “d.dddddd°”, the amount of Ds being the number of digits displayed.
   
5. On the “GPS” tab, make the following changes.

• Protocol: NMEA 0183
• Bits per Second: 9600
• Data Bits: 8
• Parity: None
• Port: The COM you set in GpsGate
• Stop Bits: 1
• Flow Control: None
  
  

That’s it for settings! If everything is set up correctly you should see a globe indicator in the bottom right corner of Network Stumbler with GPS coordinates as well.

Recap:

1. Power on the Nuvi, put in GPS mode and connect it to the laptop.
2. Fire up GpsGate and let it grab a satellite signal from the Nuvi.
3. Open Network Stumbler and set the COM Port to one emulated by GpsGate.
4. Drive around and hunt WiFi. Router/Access Point locations are being recorded too!

The best part of the whole operation is mapping the data. Once you are satisfied with the findings, save an *.ns1 file of your discovered networks.

Here is a site that accepts *.ns1 files and plots networks on Google Maps. http://www.gpsvisualizer.com/map_input?form=wifi

I hope you find this guide informative as it took me about 2 days to write! Please leave feedback, either by comments or email! I would love to hear how things worked and maybe even see some of your maps. Happy hunting!