OsmocomBB team member Andreas Eversberg has been working on a new RSSI monitor firmware application within OsmocomBB.
Using this firmware, it is possible to monitor the RSSI of individual ARFCNs or even the entire spectrum.
Depending on the hardware capabilities (e.g. Hardware/FilterReplacement), it is also possible to measure the uplink RSSI.
More details are available at rssi.bin.
The current status of this firmware is available from the
laforge/monitor branch in git, but is expected to be merged soon into master.