Fig. 5.4: Fsk Modulation Example; Fig. 5.5: Pwm Modulation Example; Fig. 5.6: Hmf1 Settings - Hameg HMF2525 Handbuch

Fig. 5.4: FSK modulation example

al parameters is performed via the numerical keyboard
the knob .
10
5.1.5 PWM modulation

Fig. 5.5: PWM modulation example

With the PWM modulation (pulse width modulation), the pulse
width is depending on the modulation signal. The Devia-
tion means the value of the pulse width variation and can
be entered as percentage by using the numeric keyboard or
the knob (depending on the signal period). If for example a
pulse signal with a duty cycle of 20% and a PWM modulation
with a deviation of 5% is chosen, the duty cycle of the output
signal varies from 15% to 25% (depending on the modulation
signal).
The pulse width modulation (PWM) is only available with
the pulse waveform. It will be automatically chosen when
the waveform function pulse is selected.
5.1.6 Internal modulation source
With the internal modulation source (Source Int.) the
carrier signal will be modulated with an internal built-in wa-
veform. The soft key menu item Shape offers the following
E x t e n d e d o p e r a t i n g m o d e s
modulation waveforms, available for the modulation types AM,
FM, PM, and PWM (Built-in waveforms):
– Sine function
– Square function 50%
– Positive / Negative ramp function
– Triangle function 50%
– White noise function
– Pink noise function
– Cardinal sine
– Exponential rise / fall
The selected function will be indicated in the lower menu field.
The values of the parameters are set using the numerical key-
board or the knob
4
signals can be load (Non volatiles waveforms).
More information about user defined waveforms please refer
to chapter 4.7.
5.1.7 External modulation source
or
4
With the external modulation source (Source Ext.) the
carrier signal will be modulated with an external waveform.
External modulation signals are connected to the rear panel
connector MODULATION INPUT
The modulation signal is influenced by the level of the ex-
ternal modulation source. 1V corresponds to 10% modu-
lation, 10V corresponds to 100% modulation, etc.
To demonstrate the external modulation two HMF function
generators will be linked togehter. HMF1 corresponds to the
modulation source and HMF2 corresponds to the modulator.
In our modulation example a voltage from -5V to +5V will influ-
ence the pulse width (PWM) between 0% and 100%, depending
on the set instrument value. The signal shape of the external
modulation signal has an influence to the resp. modulation
frequency and appearance. The following procedure should
help you to understand the functionality and the external mo-
dulation setting.
On HMF1 (modulation source) choose the sine wave function
with a Frequency of 1Hz and an Amplitude of 10V.
Connect the SIGNAL OUTPUT of the HMF1 with the MO-
DULATION INPUT connector of HMF2 (modulator) using
a BNC cable and activate the signal output (OUTPUT button
highlighted).
From now on all settings are made at the 2nd HMF (HMF2).
Choose the pulse function of the HMF2 and set a Duty
cycle of 70%. Pressing the MOD button automatically sets
the PWM modulation function. Now set the Frequency and
Deviation of the modulation to 10kHz and 30%. Set the
modulation source to external (Source
ignore the setting of the signal shape as you are using the
external modulation input.
. Additionally, user defined arbitrary
10
.
22

Fig. 5.6: HMF1 settings

Ext.). You can
Subject to change without notice
41