HW V4 / © 2005 – 2013 Aaronia AG, DE-54597 Strickscheid
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Manual Spectran V4
First measurement
For optimal acoustic reproduction of signals, you can select
different filter bandwidths using the Up/Down arrow keys.
The selected filter is displayed in the large Info display. All
available RBW filters (for example: 3kHz, 1MHz etc.) are
selectable.
Often, you will not be able to exactly „hit“ the center frequency
of a signal, and demodulation is bad or impossible. Thus, you
can fine-tune the center frequency using the right/left arrow
keys. The step width used is derived from the selected filter.
Should you have chosen, for example, the 1MHz filter, steps
are 1MHz wide etc.
When changing the center frequency, it will be shown on the
main Info display (full MHz)
Examples:
-Cell towers / cell phones:
A GSM900 / GSM1800 cell tower (keys 5/6) emits a
„beeping“ or crackling“ noise with many interruptions and
morse-like „pulsing“. This is the so-called “control channel”,
which is always active and “beeps” exactly at 1733.33Hz.
When one or more cell phones are active, you can recognize
an additional 217Hz “crackling” noise (similar to morse code).
An optimal reproduction can be achieved with the 1MHz or
3MHz filters.
-DECT phones:
An easily recognizable signal source ist he base station of a
DECT phone (key 0). It produces a 100Hz “humming” sound.
You can simply “prove” this by disconnecting the mains from
the base station: the hum disappears. When you turn the power
back on, the hum will reappear after a few seconds.
Good reproduction quality is achieved by using the 1MHz filter.
Attention: For optimal reproduction of a signal, its level should be at least
-70dBm, even better stronger than -60dBm.
Tip
: Optionally, you can even visualize the demodulation using a LF spectrum analyzer. The
Spectran NF series lends itself optimally for this purpose, as the NF-3020 and above offer
the required signal input.
