Simple IEEE 802.15.4 2.4GHz spectrum analyser

The IEEE 802.15.4 standard describes the physical layer and medium access control for low-power and low rates personal area networks, in the 2.4GHz ISM band it has been widely used for Wireless Sensor Networks (WSN), and now recently for low-power IoT applications.  This band is also used by other technologies like WiFI and Bluetooth, and as new products and solutions using the same band increase the available spectrum gets crowdier.

There's a nice article at Digikey which describe how wireless protocols and technologies overlap and coexist in the 2.4Ghz band.

The rssi-scanner application provided as a defacto Contiki example allows to sniff the noise floor level of channels 11-26, the ones specified by the standard, useful to have an idea of how the spectrum looks like and if the selected operating channel might be prone to congestion and packet loss, due to interferences from other devices.

To install Contiki you can follow the instructions from their website, either by downloading the Instant Contiki Virtual Machine, or cloning the repository hosted at Github.

Then using the Zolertia Z1 mote just follow these steps:

cd examples/rssi-scanner

make TARGET=z1 savetarget

make clean && make rssi-scanner-cc2420.upload && make viewrssi

This should open a new window as follow:

The cc2420 radio transceiver on board the Z1 mote is quickly changing channels and reading the RSSI level, then printing the value over the serial port to a Java-based application.  The values can also be stored locally to be plotted afterwards.