Rear Panel Connections; Modulation Input; Sweep Out; Ref Out/Ref In - Hameg HMF2525 Handbuch

8 Rear panel connections

8.1

Modulation input

The HMF2525 / HMF2550 allows to control the amplitude of the
output signal by an externally applied DC voltage to the MO-
DULATION INPUT connector
will influence either the output amplitude (AM), the frequency
deviation (FM), the phase (PM), the hop frequency (FSK), resp.
the pulse width (PWM) between 0% and 100%, depending on the
value set at the instrument. The frequency, resp. the signal shape
of the external modulation signal has an influence to the resp.
modulation frequency and appearance.
8.2

Sweep out

The sweep sawtooth is available at the BNC connector SWEEP
on the rear panel, the signal runs from 0 V (start fre-
22
OUT
quency) to +5 V (stop frequency). For further information about
the SWEEP function please refer to chapter 5 „Extended ope-
rating modes".

Fig. 8.2: Swept sine wave; sawtooth output

8.3

REF OUT/REF IN

In order to increase the frequency stability the internal oscil-
lator may be replaced by an external reference which can be
connected to the 10 MHz REF IN/REF OUT connectors
Fig. 8.1: Signal inputs
and outputs including
modulation input
. A voltage from 0 to +5 V
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R e a r p a n e l c o n n e c t i o n s
/ on the rear panel. The external reference frequency
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signal must comply with the specifications given with respect
to frequency accuracy and amplitude.
Push the MENU key and select the soft menu key System
8
and Clock in order to select an external reference.
8.3.1 Phase synchronization
The function generators of the HMF series can be synchronized
by using the 10MHz BNC inputs and outputs on the backside.
In this case one instrument is the „Master" and another instru-
ment is the „Slave".
Please proceed as follows in order to synchronize two HMF
instruments with each other:
– Connect the 10MHz Ref OUT output on the backside of
the master with the 10MHz Ref IN input of the slave.
In this case, both instruments will use the same (internal)
10MHz reference clock of the master. Consequently the si-
gnals are already frequency synchronized, but phase-shifted
to a (random) fixed angle.
– Now connect the front TRIG OUTPUT of the master with
the front TRIG. INPUT of the slave. This will phase-
synchronize the output signals.
The following device settings are required to perform the syn-
chronization:
Master:
Press the MENU key followed by the System soft key. Then,
press the Trigger soft key and activate the TRIG. Source
in the submenu.
Slave:
Press the MENU key followed by the System soft key. Then,
press the soft key Clock and set the clock from Int. to
Ext. Now, the previously grayed-out menu item Synchro.
is active. Select the synchronization type (manually via REMO-
TE button or automatically) using the soft key Synchro. and
the knob. The instrument will automatically synchronize (or in
manual mode by pressing the illuminated key REM/TRIG)
with the master signal.
HAMEG only supports the phase synchronization of two
devices. A specific phase shift function of the signals is not
provided.
If both signals are phase synchronized, you can affect the pha-
se angle of the signals by changing the frequency of the slave
signal. In this case, increase the signal frequency of the slave
slightly. Now, you can see that the signal begins to „migrate". If
the desired phase angle is reached, reduce the frequency back
to the value of the master. The signal is „stationary" again. By
using the same 10MHz reference clock the phase angle should
be constant. Please note that the device must be in the manual
synchonization mode.
Subject to change without notice
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