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EXTERNAL MODULATION
The equation defining the relationship of instantaneous modulation voltage to the
envelope amplitude is:
VenveJope(Vp-p}
where Vcarrier
-10V
Vmodulation
Observations:
-The carrier amplitude is 1/2 the displayed value when VmoduJation
-The envelope
-The carrier is 180
more negative than
-The Reduce Input light will come on when modulation is
tion is
100%. AM modulation
#1 of the Status Byte is unmasked. The Reduce Input light's HP-IB equivalent is
over the maximum amplitude allowed in each amplitude range. Note: Amplitude
>
modulation
100% will not necessarily distort the AM envelope. The AM
envelope is distorted when distortion sidebands are present, not when the ratio of
total sideband power to carrier power is greater than 1. A synchronous AM detec-
tor is required to recover the modulating signal undistorted. Note that a non-
synchronous detector such as a peak detector, cannot recover the modulating
signal, undistorted. The Reduce Input light and'" E50" are inhibited while in either
of the
Lock modes when the phase locked loop is unlocked.
Vmodulation
2
=
the 3314A's displayed amplitude and
+
10V
=
0
out of phase when Venvelope is negative IVmodulation is
-
1V} .
100% can be sensed from the HP-IB when bit
-)
1
+
x VcarrierlVp-p}
2
=
-lV.
57
(cant)
100%.
OV.
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