Inhaltsverzeichnis
Werbung
Verfügbare Sprachen
Verfügbare Sprachen
O p e r a t i o n o f t h e H M 8 1 3 0
currently in progress is interrupted and a new sweep is started.
At the same time, the activated parameter is shown in the
display. As soon as sweep mode is enabled, the start frequency
is shown in the display, unless the stop frequency is currently
being selected. The sweep proceeds linearly from the start
frequency to the stop frequency and can go either from low to
high frequencies or vice versa. A sawtooth signal
corresponding to the sweep pattern is available at the BNC
jack SWEEP OUT
at the rear panel. The output voltage range
is 0 V (start frequency) to +5 V (stop frequency).
Controlling the output voltage
The output signal of the HM8130 can be controlled by means
of an applied external DC voltage. The BNC jack AM – IN
the rear panel is used to apply the control voltage. A signal
between 0 V and +5 V applied to this jack attenuates the output
voltage of the HM8130 and changes the set output voltage to
max. zero volt.
Attention: The displayed output voltage remains
unchanged.
If the output is not terminated (no load), the output voltage
can be calculated using the following equation:
STOP
V
= V
x K
out(pp)
display
with K = (5 V - external DC voltage) / 5.
The output voltage of the HM8130 is varied within the previously
set voltage range. By applying an external voltage of 5 V, it is
also possible to achieve an output voltage of approx. 0 Volt at
the output of the HM8130.
Amplitude modulation
The HM8130 is not equipped with any internal means of generating
an amplitude-modulated signal. However, the BNC jack AM - IN
on the rear panel can be used for this purpose. An external
signal for amplitude modulation can be applied there. Modulati-
on factors up to 100% can be achieved. Since a bipolar signal is
needed for this modulation, it is necessary to superimpose the
input voltage with a DC offset of 2.5 V. Ideally, this should be
obtained from a function generator with an offset function (e.g.
the HM 8030). In this cases, the amplitude shown in the display of
the HM8130 is greater than the actual output voltage.
Figure 8: Swept sine wave; sawtooth output
24
Subject to change without notice
To set the external DC voltage for optimum amplitude
modulation symmetry, proceed as follows:
st
1
Do not apply any signals to the external input.
nd
2
Set the HM8130 to the desired output voltage (V
rd
3
Measure the amplitude of this signal.
th
4
Apply a DC signal to the AM – IN
until the output voltage of the HM8130 is attenuated to 50%
of its previous amplitude.
th
5
Apply the AC voltage for setting the desired modulation.
at
The modulation factor will now remain constant, regardless
of the amplitude of the generator output voltage is changed.
The generator output signal is modulated invers to the external
modulation signal.
Arbitrary function
In addition to the fixed signal shapes, the HM8130 allows the
generation of user-defined waveform, too. When defining this
signal, certain rules and limiting specifications must be
observed. These are described below.
Arbitrary signals are digitally generated and can therefore be
defined with fairly good resolution. The frequency and
amplitude of a waveform defined in this way can be varied like
with the "hard-wired" signals. Besides the constraints
imposed by the equipment specifications (due to the integrated
D/A converter), it must always be taken into account that freely
defined and digitally generated curve shapes are accompanied
by harmonics situated far above the actual signal frequency,
When using such signals, it is important to keep in mind the
effects that they can have on circuits under test.
With the HM8130, arbitrary signals can be defined by the
interface. Once such a signal has been defined, it is stored in
the memory of the HM8130 and can be dealt with just like one
of the "hard-wired" signals. For the definition of arbitrary
signals we recommend to use the software SW8130-V3.00
(uncluded in delivery).
The HM8130 is equipped with memory space in the form of a
1024 x 4096-point matrix. This is equivalent to a resolution of
10 bits in the horizontal and 12 bits in the vertical direction.
Figure 9 : Sinewave with AM
).
out(pp)
. Increase this voltage
Werbung
Kapitel
Inhaltsverzeichnis
