The first version i will publish here will not be with wireless communication but i will describe little about that for you.
The Arduino Nano will be used in all 4 targets. So i need 4 of them. They will be used to control and communicate with my Arduino Uno. In the Nano i will connect the Sensor on an analog pin and the indicator (Blue led) on an digital pin. I will also have indicator to show if its connected to the Uno board wireless.
For the communication with the Arduino Uno and all four targets i will use this nRF24L01 2.4GHz transmitter. So i have ordered 5 of them. I need one on each target and one on the Arduino Uno box.
Stay tune for more info about this wireless function.