GNU Radio blocks and tools to receive and demodulate the GSM downlink from an SDR. grgsm_livemon tunes a found ARFCN, demodulates the GMSK bursts, decodes the control channels (BCCH/CCCH/SDCCH) and forwards the frames as GSMTAP over UDP to Wireshark. The de-facto open-source GSM receiver, successor to airprobe.
Upstream master stopped on 2021-05-05, but Debian and Kali ship 1.0.0~20220727-3, taken from bkerler's maint-3.10_with_multiarfcn branch and built against GNU Radio 3.10.12. Source · checked 2026-09-28