Ext Ac, Ext Dc - HP 8642A Operation And Calibration Manual

Model 8642A/B
Operation
Modulation, <PM (cont'd)
Example
Phase modulate the RF output using the internal modulation oscillator at a 10 kHL rate,
with 12 radians q,M deviation.
I
ENTRY MODULATION SOURCE
ENTRY
~
I
,."
0
rnTIJ
G
fREJ
LOCAL
(keys)
DATA
I
ENTRY
DATA
OJ
IT]
~
( SHIFT
1
OM OJ CIJ
W
mV
G
%
~
(program
PM NT MF 10 KZ PM 12 RD'
codes)
*
These codes are
110t
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
.....
mo
].F
R
I 171 171 171
LJ
7
I ILI.ILI ILl
r,
L..
1;JI7IRTI
f
,_.ILI
'.If
/ U 171 171 T/ ITI
- f
1 lLJ.1LI .If Ilf
'NT
The RF output is being internally phase modulated (as indicated by the q,M and INT
annunciators) q,M deviation is 12.0 radians. Modulation frequency is set to 10.00 kHz.
The cursor above the <PM setting indicates that <PM is the active function.
EXT AC, EXT DC
How to Set <PM with an External Source
Source
Do not apply more than 15 Vpk maximum external voltage to the
FM/q,M INPUT or damage to the Signal Generator's circuitry could
result.
The external modulation source connects to the FM/q,M INPUT connector (input
impedance of 600 ohms).
The external modulation signal level should be adjusted to a I Vpk (0.707 Vrms)
sinewave input to the Signal Generator to get an actual q,M deviation equal to the
displayed <PM deviation. For example, if a 1 Vpk external modulahon source is provided,
with the Signal Generator's q,M deviation set to 50.0 radians per volt, the output has 500
radians ¢:YI deviation. (If the source voltage is reduced to 0.5 Vpk, and no other settings
are changed, the output has 25.0 radians <PM deviation)
3-) 21