Queries on RSSI readback in SSH and Reading RSSI value in python script

I have 2 questions and that would be: When I use SSH to connect to the ADALM Pluto and see the RSSI value through using the command "cat in_voltage0_rssi", sometimes it displays 115.25dB or 51.75dB but most of the time it displays 51.75dB without any input power. What is the problem behind this? The 2nd question would be, if I want to read the RSSI value in a python script, what code should I write in the python script to read the RSSI value? Is it using " iio_channel_attr_read(iio_device_find_channel(phy, "voltage0",false), "rssi", &rssi)"?