Inside the M5 E-Tag

Radioactive Networks is an Engineering Consultancy company specializing in
GPS tracking solutions, and engineering design work. You can read more about
our solutions for Tracking by clicking on TeamTrack on the menu on the

If you are looking for information on setting up an eTag account we would
suggest you visitThe M5 Motorway E-Tagsite.

Welcome to the Radioactive Networks E-Tag (E-Ztag or E-Toll) page. This page is for people who
are interested in what is inside the E-Tag used on many Australian roads. So
we have dismantled our E-Tag and provided the following photos.

From what we have seen, the E-Tag is activated by a microwave signal
transmitted to the E-Tag. This signal turns on the CPU of the Tag which then
sends back a signal with the serial number of the Tag. There are reasons to
believe that the CPU and the transmitter are actually powered by the small
battery contained in the unit. This battery is probably the most sensative
component to heat and can fail if the unit is left in direct sunight

The ‘beeping’ of the unit as it goes through a toll booth apears to be
unrelated to the function of paying the toll. The unit does not store the
toll, but just stores a serial number for the account being used. Once this
serial number is read, it is checked with a central database, and then the
unit is commanded to beep in response to the result – such as a single beep
for OK and four beeps for error.

We suspect that the frequency is somewhere between 5 and 25 GHz and as far
as we can tell it is unlicensed. We are still working to determine the
information as to what frequency is being used. The E-Tag has a C-Tick
registration number of N1661.

From a users point of view one conern that needs to be addressesd is how
secure your account is from hackers. My contention would be that there are
certainly ways that this unit could be ‘hacked’ but that there are easy ways
to the operators to catch the user doing so since they are passing by
surveilance cameras as they are commiting the fraud. The methods basically
involve building a repeater to activate other Tags and send their serial
numbers to the reader.