The Windows GUI version of hdhomerun_config will display the signal strength and signal quality updating every second.
Under linux or osx you can use “watch” with hdhomerun_config:
hdhomerun_config FFFFFFFF get /tuner0/channel 8vsb:
watch hdhomerun_config FFFFFFFF get /tuner0/status
(If you have more than one HDHomeRun then specify the device ID rather than FFFFFFFF)