Extended Operating Modes; Modulation Types (Mod); Amplitude Modulation (Am); Fig. 5.1: Am Modulation Example - Hameg HMF2525 Handbuch

E x t e n d e d o p e r a t i n g m o d e s

5 Extended operating modes

5.1

Modulation types (MOD)

A modulated signal consists of a carrier signal and a superim-
posed modulation signal. The HMF2525 / HMF2550 offers the
following types of modulation: AM (amplitude modulation), FM
(frequency modulation), PM (phase modulation), PWM (pulse
width modulation), and FSK (frequency shift keying). The type
of modulation is selected by pushing the MOD key and choosing
the modulation type with the knob in the soft menu TYPE. Only
one type of modulation may be active at any time.
All basic signal function (except the sine function) are generated
by an internal arbitrary generator. This generator also produces,
(except sinusoidal modulation) the modulation types.
Internal (Source Int.) or external (Source Ext.)
modulation can be chosen.

5.1.1 Amplitude modulation (AM)

Fig. 5.1: AM modulation example

With AM modulation the amplitude of the carrier signal will
be changed by the amplitude of the modulating signal. After
selecting AM in the soft key menu Type the modulation depth
can be set from 0% to 100% in 0.1% increments (Depth).
With the amplitude modulation the envelope of the output
signal changes according to the frequency and amplitude
value of the modulation signal.

5.1.2 Frequency modulation (FM)

With FM modulation the frequency of the carrier signal will be
varied according to the instantaneous value of the modulating
signal, the amplitude remains unaffected. The Deviation
is the maximum frequency deviation of the modulated signal
from the carrier frequency.
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Subject to change without notice

Fig. 5.2: FM modulation example

5.1.3 Phase modulation (PM)

With PM modulation the phase of the carrier signal will be shifted
according to the instantaneous value of the modulating signal. The
Deviation describes the maximum deviation of the modula-
ted signal phase from the carrier signal. Values between -180°
and 180° can be set by using the knob.

Fig. 5.3: PM modulation example

5.1.4 FSK modulation
The modulation type frequency shift keying (FSK) generates a
signal which alternates between two predefined frequencies:
the carrier and the hop frequency. The alternation will depend
The modulation type FSK can be only performed in combi-
nation with a TTL signal at the TRIG INPUT socket.
on the FSK rate set in the internal source mode (Rate) or on
the signal at the trigger input TRIG INPUT
source mode. Both carrier and hop frequencies may be set
entirely independent of each other. The setting of the individu-
in the external
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