Rohde & Schwarz R&S FSP Series, Operating Manual

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Operating Manual 1164.4556.12 - 06 2.5
R&S FSP Getting Started
Measuring the Spectra of Complex Signals
➢
Press the RES BW MANUAL softkey and enter 10 kHz.
By reducing the bandwidth, the noise is further reduced and the
intermodulation products can be clearly seen.
5. Measuring intermodulation by means of the 3 rd order intercept
measurement function
➢
Press the MEAS key.
➢
Press the TOI softkey.
The R&S FSP activates four markers for measuring the intermodulation
distance. Two markers are positioned on the useful signals and two on the
intermodulation products. The 3
rd order intercept is calculated from the level
difference between the useful signals and the intermodulation products. It is
then displayed on the screen:
Fig. 2-1 Result of intrinsic intermodulation measurement on the R&S FSP. The 3 rd
order intercept (TOI) is displayed at the top right corner of the grid
The level of a Spectrum 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.
6. Increasing RF attenuation to 10 dB to reduce intermodulation products.
➢
Press the A M PT key.
➢
Press the RF ATTEN MANUAL softkey and enter 10 dB .
The R&S FSP’s intrinsic intermodulation products disappear below the noise
floor.