This measurement indicates whether or not video signal levels are properly represented in the RF signal. The NTSC modulation scheme yields an RF signal that reaches its maximum peak-to-peak amplitude at sync tip (100%). In a properly adjusted signal, blanking level corresponds to 75%, and peak white to 12.5%. The zero carrier reference level corresponds to 0%. Refer to the diagram at the right. Over modulation often shows up in the picture as a nonlinear distortion such as differential phase or differential gain. ICPM or white clipping may also result. Under modulation often results in degraded signal-to-noise performance.