Using the T15 Controller app on their iPhone, user can now turn on (activate) or turn off (deactivate) their miniature T15 radio frequency transmitter. Previously, either external magnets (for reed switch on/off control) or a separate light control box were necessary.
The pulses of light transmitted by the iPhones camera flash contain an embedded code that only T15 transmitters understand. Because the LED flash is so bright and the code is very complex there is no worry that the T15 transmitters will be accidentally receive a command via any other indoor or outdoor light source.
In order to reduce the size of the T15 wildlife tracking transmitter (to the smallest size telemetry transmitter in the world) conventional activation and deactivation devices (such as magnetically controlled reed switches) had to be abandoned. This also gives biologists the added convenience of being able to control their T15 transmitters with a device that is normally with them all of the time...their iPhone!