R&S ESR Series User Manual page 439

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R&S ESR
2. The level of a signal analyzer's intrinsic intermodulation products depends on the
RF level of the useful signals at the input mixer. When the RF attenuation is added,
the mixer level is reduced and the intermodulation distance is increased. With an
additional RF attenuation of 10 dB, the levels of the intermodulation products are
reduced by 20 dB. The noise level is, however, increased by 10 dB.
Increase the RF attenuation to 20 dB to reduce intermodulation products.
The R&S ESR's intrinsic intermodulation products disappear below the noise floor.
6.4.4 Measuring Signals in the Vicinity of Noise
The minimum signal level a signal analyzer can measure is limited by its intrinsic noise.
Small signals can be swamped by noise and therefore cannot be measured. For sig-
nals that are just above the intrinsic noise, the accuracy of the level measurement is
influenced by the intrinsic noise of the signal analyzer.
The displayed noise level of a signal analyzer depends on its noise figure, the selected
RF attenuation, the selected reference level, the selected resolution and video band-
width and the detector. The effect of the different parameters is explained in the follow-
ing.
User Manual 1175.7068.02 ─ 12
Spectrum Measurements
Advanced Measurement Examples
436