Spectrum Analysis signature

Hello ! community,

I have just performed a spectrum analysis in a building under construction equipped with very little equipment.
I notice on the analysis a traffic on the 2.4 GHz band, this looks like ZigBee but does not correspond to the Zigbee channels.

It is certainly a question of communication between home automation equipment.
Have you ever seen this signature before?

Thank you for your help,


Dear Hadrien

these can be Zigbee channels; see the channel plan of ZigBee versus WiFi:


Do you see this everywhere in this building and as continuous signals? They now look continuous for the 10s span you have. As there is nothing finished in the building, I can imagine that these devices are looking for the right channel and are in a sort of scanning mode.
They have a coexistence mechanism to limit normally the used channels to the ones in red in the drawing once they notice WiFi signals so with AP deployed, it should sort itself out.

I haven’t seen this signature with Wifi present but it might of course be another source like Bluetooth beacons but those should also sort out once WiFi is present. It looks too ‘perfect’ to be random interference of electro engines or so. the good news then is that someone should know what they deployed :slight_smile:

I would recommend switching the labels in Chanalyzer to ZigBee, and see if they line up. If they perfectly line up with the signatures, then that’s a good sign that you’re looking at ZigBee. If they don’t line up, then it’s probably some other wireless technology, possibly frequency-hopping since they’re different heights.

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Yes, I see the signals throughout the building as a continuous signal. My Wifi network is indeed not yet deployed.

If I display the Zigbee channels on the capture I notice that the traffic is not centered on these channels that’s why I found it strange. But I suspect air conditioning blocks for example that communicate with each other…

Thank you for your help. :slight_smile: