Which radio signal is emitted by uBeacon ?
Radio signal emited by uBeacon Mesh v2.0 is within the frequencies 2.402-2.480GHz. The transmitter power varies within range -22.5dBm to +7.5dBm (which equals 5.6mW). In open field it can give up to 300m of range (measured with iPhone 4s and iPod 5 using CoreBluetooth framework).
The TX Power variable is responsible for setting the power of transmitter. With uBeacon it can vary from 0 to 7, with 0 corresponding to minimum and 7 for maximum power.
The default value we found to be a good balance between power
consumption and range is TX power = 5.
If you need to have a stronger signal to cover more area you can increase it to 7 which will set the transmitter to +7.5dBm. Be aware that changing from 5 to 7 will slightly increase the peak current consumption value. For more details on power consumption refer to the Power consumption article.
The following graph shows signal strength measured with an iPod in open field while scanning with CoreBluetooth