I have developed a GSM-based APRS unit using the Telit EZ10 GSM/GPS module. It connects to one of three standard APRS IGate servers (2 in South Africa, and one in USA), although this is configurable, and they are prioritized.

The main reason for such a unit was because of the wide open spaces in South Africa with poor APRS digipeater coverage, and a very good GSM infrastructure, a vehicle can be tracked throughout South Africa. Yes, HF can be used, but requires HF in the mobile that can only be used for APRS. I felt this to be a bit of a waste.

Once the position is sent to one of the IGate servers, the position is sent through the APRS network as every other APRS message, so it can be seen on any of the APRS clients, as well as being relayed back onto the RF network.

The APRS firmware is written in Python and runs on the EZ10 module. To install the binary files onto the EZ10, as well as configure the unit, download and install the EZ10 APRS Installer v 1.2.0.3 (Please email me for a copy or the source files). Note: You will require the latest Telit EZ10 firmware so download and install GM862-GPS Firmware Update 7.02.404 if not already installed. The Uploader will not allow you to install the files on the EZ10 if this version is not already on the EZ10.

The Telit EZ10 is available in South Africa from RF Design. They are running a special price for all licenced Radio Amateurs. Contact me for further information.



On running the Uploader, the above screen will appear. Start by setting the comm port that you will be communicating with the EZ10. This is done by clicking the Option Button. Do not change any of the other comm port settings. Next, setup your call sign that will be displayed on the APRS clients (e.g. UI-View). In order to connect to the IGate servers, you require a valid password (Validation number in UI-View). From Version 1.2.0.0, it is calculated automatically. Lastly in this block, you need to input the icon that you would like displayed. Clicking on the Help button will display a PDF file with the various icons, and their related table and icon codes. (Default is a car).

From Version 1.1.0.0, the Beacon Message box was added. In the box, you can select what is sent with your position, except for the Debug box. The Debug box is for diagnosing problems and should not normally be ticked. As for the User Beacon, you can add any text you like up to 30 characters. You also define how often you want the beacon sent - this is after x number of transmissions, where 0 turns off this feature.

In the Setting block, you will find the various timing parameters. I suggest leaving them as default so as not to flood the various APRS networks.

The Server block is for editing the default servers. The servers are prioritized, so server 1 is always tried first, then 2 and 3 if required. You can leave these as defaults, or change them to your local servers. It is recommended that you use port 14580 so as to reduce the data being sent to the EZ10, and hence, reducing the cost of the data.

The last block is for a SIM PIN number should you want to use one.

You can now save this configuration by pressing the Save button. You are also able to load a previously saved profile by pressing the Load button.

Now it is time to upload the files to the EZ10. Firstly, you need to connect your EZ10 to the selected comm port. Click on the Connect button and follow the instruction from the Uploader. Once you are connected to the EZ10, the Upload button will be active. Click on the Upload button, and the files will be sent to the EZ10. When it is completed, you need to cycle the power to start the new firmware.

Comments from users:

1. Ensure that your SIM card is enabled for GPRS. This may require a call to your service provider, and may require that a valid call is made with the SIM card before inserting it into the EZ10.
2. My software provides diagnostics via the serial port at 115200 baud. When the unit does not seem to be working correctly, connect a PC to the serial port and it will guide you to solving the problem.
3. There are some jumpers in the EZ10 that need to be in a specific position for the software to autostart every time. This file contains the required jumper settings.

Features still to be added:

1. Moving and stationary beacon messages.
2. Additional hardware to provide a messaging and tracking display.
3. Automatic FTP Over-the-air updating of the firmware.
4. And more of your ideas.

Fixes in Version 3.2.3.2:

1. Fixed a bug in one of the debug routines in the GPRS file.
2. Improved the Uploader to reduce timing errors and programming of the EZ10 problems.

Fixes in Version 3.2.2.2: (Updated 10 June 2008)

1. Added the GSM signal strength as part of the message.
2. Dropped the number of sats for a valid position to 4.
3. Changed the inactivity timers to improve reconnection on loss of server.
4. Added network info everytime a connection is made to an open socket in the diagnostics.
5. Added the deleting of files on the EZ10 before uploading newer version (Bug fix as detected by Allan (ZS1LS) and Peter (ZS1OA)).
6. Added delays when uploading files larger than 1KB (Bug fix as detected by Allan (ZS1LS) and Peter (ZS1OA)).

Fixes in Version 3.1.1.0:

1. Fixed bug in returning to command mode after communications with the server.
2. Force a position 1 minute after stopping.

Should you have any problems, queries or make changes to the source files, please send me an email at andy(at)zs6cey.org.