HP 8901B

Model 8901B
Operation
LOCAL
(keystrokes)
EXAMPLE
1
DETECTOR DE-EMPHASIS
’ CC~SPLW 750~s
To measure the positive peak FM deviation of a carrier with 750 ps de-emphasis inserted before the
deviation measurement:
PRE DISPLAY On PRE DISPLAY Off
(program codes)
Measurement De-emphasis
Detector
HP-IB PROGRAM CODES
I FM De-emphasis I
Time
Constant
(L4
Filters off
25
50
75
750
P1 P3 POP3
P1 P4 POP4
POP5
Input/Output Status.
When selected, the de-emphasis networks are inserted in the audio signal path following the audio
filters. They will affect the output signal at MODULATION OUTPUT/AUDIO INPUT and can be
placed before the audio detector and display. (Refer to the block diagram in FM.) De-emphasis has no
affect on the rear panel FM Output.
When Measuring Low Deviation FM
When 750 ps de-emphasis is selected, FM sensitivity at the MODULATION OUTPUT/AUDIO
INPUT is increased by a factor
of ten. The range of deviation measurements is restricted to
40 kHz peak deviation or less after de-emphasis. The display resolution, however, remains the same as
without de-emphasis unless the pre-display mode has been selected at which time the display resolution
increases ten times. This feature provides greater resolution for measuring low deviation FM.
3-160 FM De-emphasis