The spectrum analyzer is a powerful tool and has many applications.To those who have never used the instrument,these applications may not be readily apparent.To illustrate some of the applications,the following signals,their applications their descriptions and spectrum analyzer display,will be presented.
(i) Pure sinusoid with no Modulation or Harmonic Distortion-This signal is characterized by a signal spectral line regardless of what the dispresion of the spectrum analyzer is or the IF filter bandwidth.
(ii) Amplitude Modulation-When a carrier is modulated with amplitude modulation,two side band are generated,one above the carrier frequency and second below the carrier frequency.The separation in frequency between the corner and side bands is equal to the modulation frequency.
(iii) Frequency Modulation-Frequency modulating a carrier produces side bands that are centered around the carrier as in the case of amplitude modulation,except that more than one side band generated.The number of side bands and the amplitude of those side bands is described by complex formulas based on the Bessel functions.
(iv) Asymmetrical Spectra-The generation of a spectrum that is and symmetrical about the carrier is usually an indicationthat both frequency and amplitude modulation are occurring simultaneously.