Capture Ratio
Capture ratio is the signal-level advantage needed for an FM tuner to favour the stronger of two signals on the same frequency.
It is expressed in decibels under specified test conditions. A lower required ratio indicates capture with a smaller difference between the competing signals.
Capture Ratio — Tuner
For a tuner, this describes co-channel reception rather than separation of stations on nearby frequencies. It helps characterize what happens when two transmissions reach the antenna on the same channel.
Compare the same measurement method and operating mode. Do not interpret a larger ratio as better rejection in the way a larger selectivity figure can be. Capture ratio does not state weak-signal sensitivity, and it cannot guarantee clean reception where competing signals and multipath change at the listening location.