Rohde & Schwarz HMS-X, Руководство пользователя

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65
Instrument Functions
The OUT terminal of the bridge needs to be connected to
the input (INPUT) of the spectrum analyzer. At first, you
have to let the DUT terminal open which equals total mis-
match. Afterwards, a short calibration measurement will
perform. A review of these two signals with the trace math
will illustrate that both measurements are phase shifted by
180°. The white waveform describes the open calibration
measurement, the yellow waveform describes the short
calibration measurement. Based on the trace math (TRACE
- MEM) a total compensation of the measurement devia-
tion is archieved and the deviation of the device under test
to a zero measurement will be shown.
The measured reflected energy by the spectrum analyzer
which will now indicate the algebraic difference between
both measurements in dB which is the desired return loss.
Once the return loss has been determined use the table on
the VSWR measuring bridge to read the Reflection Coef-
ficient and the VSWR. More detailed information about the
VSWR measuring bridge HZ547 you can find in the appro-
priate manual which can be downloaded from our home-
page www.hameg.com.
6.12 Auto Tune
By pushing the AUTO TUNE key the instrument performs a
scan at full span, locate the maximum peak value and cen-
ter it in combination with applicable RBW and span set-
tings on the display. This is a comfort function to assist the
user. The closer the signal level is located to the general
noise floor, the harder the peak is detectable for the AUTO
TUNE algorithm. Therefore, it is possible that the settings
must be slightly adjusted by the user. This process can
hold up few seconds.
6.13 Receiver-Mode
By pushing the MODE key a setting menu will be opened
which allows to switch between sweep mode (analyzer
mode) and receiver mode. The spectrum analyzer acts like
Before starting the wizard you have to select a trace detec-
tor. The selected detector will be used during the measurement
automatically.
a receiver which measures the level at a preselected fre-
quency. The most important parameters such as e.g. fre-
quency, amplitude, resolution bandwidth may be set using
the appropriate keys and can be vary via knob or numeri-
cal keyboard. In the receiver mode the same bandwidths
are available as in the spectrum analyzer mode. Additio-
nally, the bandwidths 200 Hz, 9 kHz, 120 kHz and 1 MHz are
available with avtivated EMC option R&S®HMS-EMC resp.
R&S®HV213 for EMI emission measurements according
to CISPR. Following detectors are available in the receiver
mode and can be set with the softkey menu DETECTOR:
❙ PEAK : displays the highest level during the set
measurement time.
❙ AVG : displays the linear average of the measurement
signal within the selected measurement time.
❙ QPEAK : evaluates the measurement signal according to
the evaluation curves defined in the CISPR standard (only
available with R&S®HMS-EMC resp. R&S®HV213).
❙
RMS
: takes the RMS value of the measurement signal
during the set measurement time.
The measurement time is the amount of time during which
the spectrum analyzer collects measured values and com-
piles them into a display result for the selected detector.
With the soft menu AUDIO the R&S®HMS-X offers an AM
and a FM demodulator allowing listening to modulated sig-
nals. The demodulated signal can be listened with a head-
phone and an intern speaker. The headphone is connected
to the headphone connector
31
(3.5 mm female connec-
tor). If the headphone is activated, the intern speaker will
be deactivated. The respective softkey allows to switch the
demodulator on or off and to set the volume (0% to 100%).
If an AM or FM demodulation is activated, the device demodula-
tes the signal and can not perform a level measurement simulta-
neously. The unit shows n/a dBm on the display.
Fig. 6.15:
Display layout in receiver mode
Dispaly of measurement time (MT) Display of bandwidth
Display of reference level
(Ref) and attenuator(Att)
Display of frequency
and amplitude
Softkey inscription in
receiver mode