This document is an vintage technical publication titled "The Notebook" (Number 33), published by the Boonton Radio Company based in Rockaway, New Jersey.Document OverviewMain Article: "New Techniques In FM Linearity Measurement"Author: John P. Van Duyne, Engineering ManagerContent Focus: The text discusses methods for measuring and improving the linearity of transfer characteristics in electronic communication equipment, specifically focusing on FM (Frequency Modulation) systems.Key Technical Concepts DiscussedLinearity Importance: The article notes that as multi-channel communication systems evolved, non-linearity in transmission characteristics caused problematic cross-talk between different channels.FM Stereo Multiplex: It highlights how the advent of FM Stereo Multiplex transmission pressured manufacturers to drastically improve the linearity of FM transmitters and receivers to minimize cross-talk between Main and Sub-channels.Nonlinear Distortion Definition: It defines nonlinearity as the characteristic of a circuit that causes its output to deviate from a straight-line function relative to its input.Distortion Terms: The text introduces standard engineering terms used to describe these effects, including Nonlinear Distortion, Amplitude Distortion, Waveform Amplitude Distortion, Harmonic Distortion, Total Percent Harmonic Distortion, and Intermodulation Distortion.