The “Analog spectrum analyser and practical measurement techniques” covers the operation of analog frequency analyzers. It describes two main architectures: the real-time analyzer, using parallel filter banks for non-stationary signals, and the sweep-tuned analyzer. The latter, based on the superheterodyne technique, sequentially measures frequencies by translating the signal's spectrum through a fixed intermediate frequency (IF) filter. Key parameters like Resolution Bandwidth (RBW) and Sweep Time are defined, as they are essential for an accurate, distortion-free analysis. Moreover it will covers the signal modulation, the process of encoding information onto a carrier wave for transmission. It details continuous wave methods like Amplitude (AM) and Frequency (FM) modulation, explaining their principles, waveforms, and resulting frequency spectrums with sidebands. Then examines the non-ideal behavior of passive components. It explains how real-world resistors, capacitors, and inductors exhibit parasitic effects like ESR and ESL, causing their impedance to vary from ideal models at high frequencies.