ESG Family Signal Generators Hardkey and Softkey Reference
I/Q
User’s Guide 4-45
Ext I/Q
Press this softkey to change the I/Q source to externally supplied I and
Q signals. Apply the in-phase and quadrature-phase signals to the
I INPUT and Q INPUT connectors. The recommended signal level is
= 0.5 V
rms
. With equal levels at I and Q, as is usually the case,
this is equivalent to 0.35 V
rms
simultaneously at I and Q. For typical
π
/4DQPSK signals, a 0.35 V
rms
waveform will be approximately
1.3 Vp-p, whereas for GMSK it will be 1.0 Vp-p. If you do not have
Option UN8, this is the only I/Q source and it cannot be changed. If you
have Option UN8, the I/Q source can also be set to an internal I/Q
source (refer to the
Int Burst softkey).
Softkey Location:
I/Q > I/Q Source > Ext I/Q
Ext I/Q Phase Polarity Normal Invert
Press this softkey to toggle between the Normal and Invert settings for
external I/Q phase polarity. In the inverted mode, the input applied to
the I INPUT connector is physically routed to the Q input port of the
internal I/Q modulator. In addition, the input applied to the Q INPUT
connector is physically routed to the I input port of the internal I/Q
modulator. This inverts the direction of phase rotation of the I/Q
modulation. If you have enabled a digital modulation format
(Option UN8 only), I/Q phase polarity will be automatically set to
normal. You can override this setting with this key.
Default Value: Normal
Softkey Location:
I/Q > Ext I/Q Phase Polarity Normal Invert
High Crest Mode Off On
Press this softkey to toggle high crest mode off and on. Turn high crest
mode on with externally-applied signals with high crest factors (such as
CDMA). High crest mode allows the signal generator to process these
signals with less distortion. With high crest factor signals, it is
recommended that the I and Q inputs seldom exceed 1.0 Vp-p. Some
output power and power level accuracy is sacrificed in this mode. This
softkey is active only if the I/Q source is external and I/Q is turned on.
Default Value: Off
Softkey Location:
I/Q > I/Q Off On > High Crest Mode Off On
I
2
Q
2
+
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