HP 8642A Operating Manual page 137

Operation
Model 8642A/B
Modulation, FM (cont'd)
Example
Frequency modulate the RF output with an external, 1 Vpk, dc-coupled source, 80 kHz
per volt FM deviation, at a rate determined by the external source's frequency.
LOCAL
(keys)
(program
codes)
ENTRY
[_™J
MODULATION SOURCE
1 EXT DC 1
ENTRY
H
DATA
no
L°J
rsi
FMXD FM 80 KZ*
* These codes are not independent and might need to follow a specific sequence for
entry. Refer to the discussion about Sequence Dependency, which begins on page 3-12 in
the HP-IB portion of this Section III.
Display
/0 0.0 00000CTZ O0.0WZ -/H0.0JJ/n
The RF output is being externally frequency modulated with an external dc-coupled
source (as indicated by the FM, EXT, and DC annunciators). FM deviation setting is 80.0
kHz per volt. Modulation frequency is not monitored by the Signal Generator when an
external modulation source is used. The cursor above the FM setting indicates FM is the
active function.
HP-IB
Keys
INT+ (EXT DC)
OFF ON
MHz
kHz
Hz
SPCL
Codes
FMBD
FMOF, FMON
MZ
KZ
HZ
SP
Keys
FM
MOD FREQ
INT
EXT AC
EXT DC
INT+ (EXT AC)
Codes
FM
MF
FMNT
FMXA
FMXD
FMBA
Comments External Modulation
External modulation frequency is not monitored by the Signal Generator. Therefore, if
the external FM source violates the maximum deviation relationships shown in Table
3-20 on page 3-112, the Signal Generator will be operating beyond its specified limits
and could lose phase lock which causes queued up Hardware Error messages.
Modulation Types Not Possible During RF Frequency Sweep
During Stepped Frequency Sweep, FM and 4>M are allowed in manual or single sweep
mode only. During Phase Continuous Frequency Sweep (Special Function 123), all
modulation types are possible.
3-110