Task of this project was to make a sensor network that are based on radio transceiver with nRF24L01(+) integrated circuit. It is necessary to detect whether an obstacle or motion exist and then over a Bluetooth connection notify a user using his Smartphone. Motion detection is done by using SRF-05 ultrasonic distance sensor and it monitors measured distance that is received by main unit, sent by sensor unit and comparing whether is that distance bigger or smaller of trigger distance, which is set by user. If it’s smaller, user gets notified by sound on main unit and information shown on his Smartphone. Sensor network is wireless and portable, so it gets supplied from DC battery. Oslo, there is a temperature and humidity measurement of air, done with DHT22 air temperature and humidity sensor. Because, all units are wireless and portable , supplied by DC battery, it is necessary to monitor battery voltage and notify a user if batteries are getting low, which is done by using a voltage divider and analog-to-digital converter that is built-in inside a microcontroller. User can change setting sending a command over Bluetooth network.