Ground loop noise is most often in the form of 60 Hz hum. Horizontal lines slowly moving up the monitor are the characteristic interference pattern of hum. Ground loops also make a transmission line susceptible to crosstalk and stray pickup from high frequency sources. Once a video signal has been infected by hum or other noise, it is impossible to filter out because the noise frequency falls within the video band. The video isolation choke presents a simple transmission line to the signal, so that its signal amplitude capability is essentially unlimited, and its bandwidth extends from DC to that frequency where line losses become excessive.
Isolation increases with increasing noise frequency.
The choke provides protection against moderate levels of 60 Hz hum, and protection against very high levels of RF noise. Its hum isolation is greater than the choke. It can sustain very high noise voltages without degradation. Isolation decreases with increasing noise frequency. A choke can be added inline to increase protection from high frequency noise.