This test is to be performed only on analyzers with Option 122 or Option 140.
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This test is to be performed only on analyzers with Option 122 or Option 140. |
Noise density is specified in dB of power per Hz of bandwidth. The "dB of power" is relative to full scale, so the units are dBfs/Hz. "Full Scale" refers to the dBm level near which the ADC will clip or overload. It is a function of Input Attenuation, Preamp On/Off, and Wideband IF Gain.
The Input Noise Density test is performed at several center frequencies and specified spans. The noise marker is used to measure the dBm/Hz. The Input Noise Density is then calculated based on the instrument’s settings. Noise specifications are given in dBfs/Hz relative to the nominal full-scale. The following formula is used to calculate Input Noise Density using the noise marker reading:
Full Scale = -16 +
Attenuation - IF Gain
-
PreampGain
(As defined in the specifications)
Input Noise Density (dBfs/Hz) = Noise Marker (dBm/Hz) - Full Scale (dBm/Hz)
All tests are performed in DC-Coupled mode.
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Test Equipment |
Model Number |
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50 ohm Termination |
909A, Option 012 |
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3.5 mm (f) to Type-N (f) adapter |
1250-1745 |
