Keysight U8903B, Руководство по обслуживанию

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3 Performance Verification for Analog Analyzer
48 Keysight U8903B Service Guide
CMRR verification
Common Mode Rejection Ratio (CMRR) is the ability of the Balanced U8903B input channel
to reject in-phase noise.
This test verifies the CMRR performance of the U8903B analyzer by using a calibrator to
generate a sine wave to the U8903B for the CMRR measurement to ensure that it is within
the published specification.
1 The BNC male-to-female T splitter and modified BNC coaxial cables with one end a
BNC connector (male) and the other end a XLR connector (male) with pin 2 and 3
shorted to carry the same signal is used for this connection. Refer to “
Modify a Cable
for the U8903B CMRR test ” on page 162 .
2 Connect the calibrator to the U8903B input channels to be tested via the Balanced
connection as shown in
Figure 3-6 . Preset both the U8903B and calibrator.
Figure 3-6 Audio generator to U8903B connection for CMRR verification
3 Configure the calibrator as follows:
– Output state: Standby
4 Configure the U8903B input channel 1 (3, 5, or 7) and channel 2 (4, 6, or 8) to be tested
as follows:
– Connection type: Balanced
– Input bandwidth: 90 kHz
– Input coupling: DC
Table 3-6 CMRR specification
CMRR specification Equipment used
≥ 80 dB (input range ≤ 3.2 V)
≥
50 dB (input range
>
3.2 V)
Calibrator
NOTE
Power on the U8903B audio analyzer for at least 30 minutes before performing the
performance verification.
Balanced input
channel 1, 3, 5, 7
U8903B audio
analyzer
Calibrator
Balanced input
channel 2, 4, 6, 8