What symptom indicates micro-reflections when checking the in-channel frequency response (ICFR) of a QAM channel?

The presence of micro-reflections in a QAM channel can be identified by observing a repetitive ripple in the frequency response. This phenomenon occurs due to signal reflections caused by impedance mismatches or other issues in the cable or connection paths. These reflections introduce phase shifts that can create periodic variations in the signal amplitude across the frequency spectrum, resulting in the characteristic ripples observed during the in-channel frequency response (ICFR) testing.

A flat frequency response would indicate a well-functioning system with minimal signal disturbances, which would not be associated with micro-reflections. An increase in signal strength or a decrease in bandwidth would suggest different issues or improvements in the signal quality rather than micro-reflections, which usually manifest as fluctuations rather than a uniform change in those parameters. Thus, the identification of repetitive ripples is key in diagnosing micro-reflections in QAM channels.