HP 8568B, Руководство по испытаниям и регулировке работы, Страница: 64 / 313

12. Amplitude Fidelity Test
Equipment
Frequency Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP
Adapter, Type N (m) to BNC (f) . . . . . . . . . . . . . . . . . . . . . HP 1250-0780
Procedure Log Fidelity
1. Set the frequency synthesizer for an output frequency of 20.000
MHz and an output power level of + 10 Set the amplitude
increment for 10 steps.
2. Connect equipment as shown in Figure 2-21.
3. Press
PRESET
)
on the analyzer. Key in analyzer settings as
follows:
[
C E N T E R F R E Q U E N C Y
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S P A N
] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . + 10
4. Press MARKER
REF
to
center the signal on the display.
5. Key in the following analyzer settings:
FREQUENCY SPAN) . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O Hz
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Hz
6. Press MARKER A. Step the frequency synthesizer output
amplitude from + 10 to -80 in 10 steps, noting
the MARKER A amplitude (a negative value) at each step and
recording it in column 2 of
2-16. Allow several sweeps after
each step for
the
video filtered trace to reach its final amplitude
(see Figure 2-22).
7. Subtract the value in column 1 from the value in column 2 for
each setting to find the fidelity error.
2-16. Log Amplitude Fidelity
Frequency 1
2
Fidelity Error Cumulative Cumulative
Synthesizer Calibrated MARKER
A
Amplitude (Column 2 Column 1) Error Error
Amplitude Amplitude 0 to 80 0 to 90
Step
0 (ref) 0 (ref) 0 (ref)
0 - 1 0
- 1 0 -20
-20 -30
-30 -40
-40 -50
-50 -60
-60 -70
-70 -80
-80 -90
2-42 Performance Tests