Aaronia SPECTRAN HF-2025, Manual

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In contrast to simple broadband detectors, demodulation only takes place aro-
und the center frequency ! The bandwidth can be set with RBW . Thus, you can
“tune in” to individual, small frequency ranges very selectively. Though, in this
mode, the filter is a bit “weaker”. Hence, very strong signals from neighboring
frequencies could “overshoot” into the actually selected frequency range and
become audible, too.
Example: You are demodulating the signal of a DECT phone (key 9), but there
is also a GSM900 transmitter nearby. Depending on the alignment of the anten-
na, you might
also hear the GSM modulation simultaneously.
The frequency-exact, systematic “acoustical analysis” is very helpful when iden-
tifying signal sources. As
demodulation is performed in realtime, it is also ide-
ally suited for quickly taking a bearing (locating) a signal source.
7.11 Pulse (measurement of pulsed signals)
This mode allows both measurement of pulsed signal sources as well as sig-
nals working with “Frequency hopping” . Examples of devices falling into this
category include DECT phones, cell phones, microwave ovens etc. By choosing
Pulse , the mode is activated and the Mode status field reads “PEAK”. By selec-
ting Std. , pulse mode is turned back off.
When set to Pulse , “real” signals display “hatched”.
ATTENTION: If possible, only use Pulse mode with small frequency ranges
(SPAN) , as in this mode, aliases and interference signals are NOT being sup-
pressed. Measurements taken with a broad frequency range (e.g. 1GHz
sweeps) in
Pulse mode can lead to significant mismeasurements. Also note that
in this mode, the noise floor is principally higher.
HINT: You can also toggle PULSE mode at any time using the Shift key.
7.0 The main menu
26
Using the DECT hotkey (key 0), a DECT phone is being measured
(pulse mode is being activated automatically). Also the Time Domain
Mode is activated. Real DECT signals are shown as a view peaks.
GSM signals would be shown as a stable number of peaks similar to a
“fence”. This offers the ability to differ between those signals.
Our free PC software “LCS” offers a even better feature: The “Timeslot
Analysis” mode. This mode offers a 3D view of the DECT signal.