Agilent Technologies E5503A Guía de usuario descargar pdf (Pagina 266)

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Agilent Technologies E5500 Phase Noise Measurement System

Residual Measurement Fundamentals

The Calibration Options

3. Measure the carrier-to-single-sided-spur ratio out of the coupler at the

phase detector’s modulated port and the offset frequency with the RF

spectrum analyzer. The RF calibration source should be adjusted such

that the sidebands are between –30 and –60 dB below the carrier and the

frequency offset of the spur between 10 Hz and 50 MHz.

Figure 8-16 Carrier-to-spur Ratio of Modulated Signal

4. Measure the carrier-to-spur ratio of the non-modulated side of the phase

detector. It must be at least 20 dB less than the spur ratio of the

modulated port. This level is necessary to prevent cancellation of the

modulation in the phase detector. Cancellation would result in a smaller

phase detector constant, or a measured noise level that is worse than the

actual performance. The isolation level is set by the port-to-port

isolation of the power splitter and the isolation of the –20 dB coupler.

This isolation can be improved at the expense of signal level by adding

an attenuator between the coupler and the power splitter.

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Agilent Technologies E5503A Guía de usuario Pagina 266

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