Hameg Instruments HM5012-2 Handbuch Seite 36

Controls and readout
A smaller IF bandwidth shows more details, but has the
disadvantage that the building up time is higher. If due to
high SPAN setting there is not enough time for building
up, the spectrum analyzer automatically increases the
time for a SPAN. This becomes visible by a reduced
measurement repetition rate.
If the lowest repetition rate is still not suitable for correct
measurement, the readout displays „uncal", as under
such circumstances the signal is displayed with too low a
level. For proper measurement the SPAN must then be
reduced until the „uncal" information is no longer
displayed. For the ease of operation it is advisable to set
the signal to the center before reducing the SPAN.
With the 4 kHz video filter activated, the bandwidth
reduces once again.
A smaller bandwidth reduces the noise and offers a higher
sensitivity. This becomes evident when switching from
1000 kHz to 9 kHz RBW.
ZERO SPAN A B A AVERAGE
SAVE B M a x
SET
SPAN RECALL A - B LOCAL/PRINT
R M
SET
24 19
22 20 17
21 18
23
(13) VBW – Pushbutton with associated „4 kHz" LED
Briefly depressing the pushbutton switches the video filter
on or off. In on condition the video filter reduces noise
using a low pass filter. Weak signals, which normally get
lost in the noise, may become visible when activating
this function.
Note:
If the video filter is activated and the SPAN is too high,
„uncal" is displayed by the readout, as the signal level(s)
do not reach their real height on the screen.
The video filter should be avoided when measuring
pulses
(14) AVERAGE – Pushbutton with associated LED
Briefly depressing this pushbutton switches this function
and the associated LED on or off. In Average mode, the
spectrum recordings are continuously calculated and
displayed as arithmetic mean value. Some functions
cannot be called in AVERAGE mode and cause only an
acoustic error message.
When the AVERAGE LED lit, briefly depressing the
pushbutton switches LED and function off and erases
the previous calculation result.
AVERAGE also activates the Max. HLD (15) function
(without displaying the result) to avoid waiting time and
enable direct switch over from AVERAGE to Max. HLD
(maximum hold).
(15) Max. HLD – Pushbutton with associated LED
Briefly depressing this pushbutton switches the Max.
HLD (maximum hold) function and the associated LED on
36
VBW 5dB/DIV
kHz
4
. H L D
dB
kHz
0
1000 10
RBW AT TE N
120 20
9 30
40
14 12 13
16
15
or off. Max. HLD stores and displays the maximum level
values of the spectrum; values below the maximum get
lost. In case of pulsating RF signals the signal reading
should not be made until the maximum signal height is
present. Some functions cannot be called in Max. HLD
mode and cause an acoustic error signal.
When Max. HLD is activated and the associated LED lit,
briefly depressing the pushbutton switches LED and
function off and erases the Max. HLD values.
Max. HLD also activates the AVERAGE (14) function
(without displaying the result) to avoid waiting time and
enable direct switch over from Max. HLD to AVERAGE
mode.
(16) LOCAL/PRINT – Pushbutton with two functions and
associated LED
1. LOCAL function
Remote mode can be switched on or off via the built in
serial interface. In remote condition the RM LED is lit and
with the exception of the LOCAL/PRINT pushbutton all
.
other controls are deactivated. Briefly depressing the
LOCAL/PRINT pushbutton switches over from remote
0 dB
(RM) to LOCAL operation, so that all controls become
.
operative again.
2. PRINT function
10
On condition that the RM-LED is not lit (LOCAL mode),
11
documentation via a PC printer can be started if the
following conditions are met:
1.The serial interface of the spectrum analyzer must
be connected with a serial PC (COM) port.
2.The provided PC software must be activated and the
software COM port setting must comply with the
hardware connection.
(17) B – Pushbutton
The spectrum analyzer contains a second signal and
parameter memory that is called „B". This memory is
volatile and switching the instrument off will lose its
content. Memory „B" can only be activated with the
instrument on, after a spectrum has been previously stored
by „A → B" function; otherwise an acoustic error message
is audible.
Briefly depressing the B pushbutton switches over to B
display which is indicated by the readout (top left position)
on the right of the center frequency display.
(18) A-B - Pushbutton
This function can be called only if a spectrum has previously
been stored in memory B. Then the result of the actual
recorded spectrum minus the content of memory B is
displayed. On the right on the center frequency the readout
shows „A-B".
The „A-B" function eases the perceptibility of changes
in signal level, frequency and shape when adjustments
are made (if the previous setting had been stored in
memory B).
When switching the „A-B" function on, the reference level
is automatically changed for better reading. A manual
correction overrides the automatic setting.
Subject to change without notice