Lambda SR1, Руководство по эксплуатации, Страница: 21 / 317

Getting Started 21
© 2014 Stanford Research Systems
When "THD+N" ratio is selected, the analyzer inserts a deep notch filter at the frequency of the
fundamental. In this case, because the notch filter is set to be tuned to the measured frequency, it is set
at the 1 kHz dominant frequency of our generator signal. The Time Domain detector then performs an
RMS integration of the remaining signal, which is distortion plus noise, and displays the ratio of that
signal to the total amplitude of the input Note that the measured THD+N ratio is -60 dB. (1 mV / 1 V =
60 dB).
To show how much more SR1 brings to a standard distortion measurement select the second analyzer
(A1) as the FFT1 analyzer. When the panel is displayed, change the source of the Analyzer to "Other
Analyzer". In this mode the FFT analyzer and the Time Domain Analyzer work as a team; the FFT
analyzer looking at the notch filtered signal from the Time Domain Detector. Take a look at the
information displayed on the FFT1 analyzer panel:
Like all analyzers the input source is displayed at the upper left. The analyzer sampling rate is displayed
at the upper right. Because we've connected the FFT analyzer to the output of the Time Domain Detector