Performance Verification for Analog Analyzer 3
Keysight U8903B Service Guide 53
DFD verification
This test verifies the DFD performance of the U8903B is within the published specification
using an internal loopback connection.
1 Preset the U8903B audio analyzer. Configure the U8903B generator output channel 1
and 2 to connect to all of its own analyzer input channels (up to 8 channels
concurrently) through internal loopback.
2 Configure the U8903B generator output channels as follows:
– Connection type: Unbalanced
– Output impedance: 600 Ω
– Output grounding configuration: Floating ground
– Waveform: DFD IEC268
– Level summation: Linear
– Output state: ON
3 Configure the U8903B analyzer input channels to be tested as follows:
– Connection type: Loopback
– Input bandwidth: 90 kHz
– Input coupling: DC
– Voltage detector type: RMS
– Trigger source: Immediate
– Measurement function2: DFD IEC 60268 2nd order
– Sample size: 131072
4 On the U8903B generator output channels, set the difference frequency to 80 Hz. Set
the center frequency of f
DUT
and the amplitude of Vrms as given in “Test record for DFD
verification” on page 116.
5 On the U8903B analyzer input channels, set the input range as given in “Test record for
DFD verification” on page 116.
Table 3-9 DFD specification
DFD specification (at 1 Vrms) Equipment used
≤–106 dB U8903B (internal loopback)
Power on the U8903B audio analyzer for at least 30 minutes before performing the
performance verification.
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