Dear K. van der Heiden,
The sniffer itself has a RX sensitivity of around –100 dBm, so it could still receive signals of such energy level. However, the maximum distance would depend more in the devices transmitting and the output power they are capable to achieve.
Between two USB-KW24D512 boards you will be able to transmit and receive within 30 meters indoors approximately. However, if another device (bigger antenna, printed antenna, power amplifier, etc.) has the ability to transmit to a long distance (i.e. TWRKW2x boards could achieve around +8dBm), the sniffer would still detect the packets from tens to hundreds of meters.
In brief, as long as the transmitted signal has enough energy, it will be detected and received by the USB-KW24D512.
Regards,
AngelC
Ok, this information is what I need for now. Thanks for you reply, AngleC!