Figure 3- -50: Effects Of Adjusting The Reference Level 3 - Tektronix CSA7404B User Manual

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Figure 3- 50: Effects of adjusting the reference level
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Figure 3- 51: Effects of adjusting the reference level offset control
CSA7000B Series & TDS7000B Series Instruments User Manual
15 dB
H Reference Level Offset. This changes the value of Ref in the equation for dB
shown above. Unlike the Reference Level control, this control actually
changes the output data values in the spectrum. Zero dB is shown on the
display screen by the marker associated with the spectral waveform.
Adjusting the reference-level offset causes the spectral waveform to move
vertically with respect to the waveform reference marker. This moves the
waveform without changing the Reference-Level control setting. Sometimes
it is beneficial to adjust this control so that the peak of a fundamental is at
zero dB. Then you can measure other harmonics in terms of how many dB
they are down from the fundamental. Touch the dBm button to preset this
level to the equivalent of 1 mW into 50 Ω.
20 dB
H Real and Imaginary Magnitudes. You may set the spectral analyzer to display
the linear magnitude of the real data or the imaginary data in the spectrum.
This is useful if you process the spectrum off line and transform it back into
a time domain trace. You could save the real and the imaginary spectrum into
a reference memory. You can export the waveforms directly into Mathcad,
Matlab, and Excel documents and update in real time.
Creating and Using Math Waveforms
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