ESG Family Signal Generators Hardkey and Softkey Reference
Phase Modulation
User’s Guide 4-71
Φ
M Source
Pressing this softkey reveals a menu of choices for phase modulation
sources. You can choose internally-generated phase modulation or
select an externally-applied signal from either the EXT 1 INPUT or
EXT 2 INPUT connectors. The internal modulation is always
AC-coupled. For the externally-applied signals, you can choose between
AC- and DC-coupled modulation. A 1.0 Vpk input is required for
calibrated
Φ
M deviation settings. The
EXT 1 LO/HI and EXT 2 LO/HI
display annunciators will turn on if the peak input voltage differs from
1.0 Vpk by more than 3%. (The LO/HI annunciators only function for
AC-coupled external inputs.)
The internal and external 1 and 2 sources have multiple uses. You can
use them for amplitude, frequency, and phase modulation. For burst
modulation, you can only use the external 1 source and you must use
the external 2 source for pulse modulation. However, any given source
can only be routed to one enabled modulation at a time. If, for example,
you were using the external 1 source in a frequency modulation
configuration for
FM Path 1, and then you configured AM Path 2 to also use
the external 1 source, the signal generator would turn off
FM Path 1 and
assign the external 1 source to your
AM Path 2 configuration. Notice that
for these purposes the external 1 AC-coupled source is the same as the
external 1 DC-coupled source and the external 2 AC-coupled source is
the same as the external 2 DC-coupled source.
Softkey Location:
FM/ΦM hardkey > FM ΦM softkey ΦM > ΦM Source
ΦM Start Rate
Use this softkey to change the starting internal modulation frequency
for swept-sine phase modulation. To change the value, press the softkey
once. The current value for the
Φ
M start rate is displayed in the active
entry area. To enter a new value, rotate the front panel knob until the
desired value is displayed, use the up and down arrow keys, or enter the
value using the numeric keypad and press the
Hz or kHz terminator
softkey. The range of values allowed is 0.1 Hz to 50 kHz. The minimum
increment allowed is 0.1 Hz.
This softkey is coupled to the
ΦMRate softkey in the initial ΦM Menu
and the
ΦM Tone 1 Rate softkey in the ΦM Dual-Sine Menu. Any value set
for
ΦM Start Rate is reflected in the ΦMRate and ΦMTone1Rate softkeys.
Conversely, if you change the value for either the
ΦM Rate softkey or the
ΦMTone1Rate softkey, the value for ΦM Start Rate is changed to match.
Default Value: 400.0 Hz
Softkey Location:
FM/ΦM hardkey > FM ΦM softkey ΦM > ΦM Waveform >
Swept-Sine > ΦM Start Rate
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