One of the areas that most tracking systems concentrate on is acquiring GPS
positions and getting them back into a central location. Some even send the
positions back to the GPS tracking units.
What has not been done is create a distributed system in the field reporting the
positions without being tracked themselves. This allows significant cost
savings in terms of not only equipment capital costs, but also in terms of
operational costs including licenses and batteries.
With this in mind, Radioactive Networks have just produced what we are
calling the 'Anti-Tracker'. Rather than develop the display interface, we
have decided to use a commercially available interface - a simple GPS
reciever.
The PRO version of this device can use eithe the $WPGPL sentences understood
by many GPS receievers that allow NMEA uploading, or GARMIN BINARY format
understood by the newer Garmin eTREX GPS receivers. This version is based on the
PIC16F876 processor with an MX614 modem IC. The code is getting close to
totally filling the memory of the processor. During testing we also
discovered that the CPU clock needed to be doubled in order to process the
data in the available time.
The position of all the users being tracked appears on the GPS receiever
allong with any roads and other features programmed into the device. Then
when the person being tracked moves, the icon on the GPS will move too.
Progress
This project is getting close to completion - at least on the firmware side.
We are now decoding normal and third party packets and displaying them on
the GPS receiver in GARMIN and TEXT modes. At present packets are not being
correctly decoded when one packet follows within 100 mSec of the previous
packet being completed. Although rare in object tracking, it is quite
common in iGate operations.
Since GARMIN and NMEA operate at different speeds, we are also going to make
the selection of the mode switchable. This needs to be implemented. The
GARMIN protocol has the ability to set ICONs and we also hope to implement
this.
Implemented Packets
For the technically minded, we will now include information on the packets that this
device will decode -
Standard Position Reports
Standard Position Reports with Timestamps
MIC-E Position Reports
MIC-E Position Reports with Timestamps
Standard Object Reports
Standard Item Reports
To Do
Remove the MAX-232 IC
Surface mount the entire board
Look at power consumption
Packet OK LED.
Fully test
ICON
TX and RX at the same time
Mode Pin
Acknowledgements
This project would not have been possible without the assistance of the
members of the PicSig on TAPR.ORG. These members put up with my stupid
questions, offering whatever assistance was required.
Please support us by purchasing one of the items from the link below. Thank You
One of the areas that most tracking systems concentrate on is acquiring GPS
positions and getting them back into a central location. Some even send the
positions back to the GPS tracking units. 
With this in mind, Radioactive Networks have just produced what we are
calling the 'Anti-Tracker'. Rather than develop the display interface, we
have decided to use a commercially available interface - a simple GPS
reciever.
The position of all the users being tracked appears on the GPS receiever
allong with any roads and other features programmed into the device. Then
when the person being tracked moves, the icon on the GPS will move too.