Agilent Spectrum Analysis Basics Application Note 150 Table of Contents Chapter 1 – Introduction . .4 Frequency domain versus time domain . .4 What is a spectrum? . .5 Why measure spectra? . .6 Types of measurements . .8 Types of signal analyzers . .8 Chapter 2 – Spectrum Analyzer Fundamentals . .10 RF attenuator . .12 Low-pass filter or preselector . .12 Tuning the analyzer . .12 IF gain . .16 Resolving signals . .16 Residual FM . .19 Phase noise . .20 Sweep time . .22 Envelope detector . .24 Displays . .25 Detector types . .26 Sample detection . .27 Peak (positive) detection . .29 Negative peak detection . .29 Normal detection . .29 Average detection . .32 EMI detectors: average and quasi-peak detection . .33 Averaging processes . .33 Time gating . .38 Chapter 3 – Digital IF Overview . .44 Digital filters . .44 The all-digital IF . .45 Custom signal processing IC . .47 Additional video processing features . .47 Frequency counting . .47 More advantages of the all-digital IF . .48 Chapter 4 – Amplitude and Frequency Accuracy . .49 Relative uncertainty . .52 Absolute amplitude accuracy . .52 Improving overall uncertainty . .53 Specifications, typical performance, and nominal values . .53 The digital IF section . .54 Frequency accuracy . .56 2 Table of Contents — continued Chapter 5 – Sensitivity and Noise . .58 Sensitivity . .58 Noise figure . .61 Preamplifiers . .62 Noise as a signal . .65 Preamplifier for noise measurements . .68 Chapter 6 – Dynamic Range . .69 Definition . .70 Dynamic range versus internal distortion . .70 Attenuator test . .74 Noise . .74 Dynamic range versus measurement uncertainty . .77 Gain compression . .80 Display range and measurement range . .80 Adjacent channel power measurements . .82 Chapter 7 – Extending the Frequency Range . .83 Internal harmonic mixing . .83 Preselection . .89 Amplitude calibration . .91 Phase noise . .91 Improved dynamic range . .92 Pluses and minuses of preselection . .95 External harmonic mixing . .96 Signal identification . .98 Chapter 8 – Modern Spectrum Analyzers . .102 Application-specific measurements . .102 Digital modulation analysis . ..