HW V4 / © 2005 – 2013 Aaronia AG, DE-54597 Strickscheid
46
Manual Spectran V4
Correct measurement
7.2.
Harmonics
A typical effect when working with spectrum analyzers:
When dealing with comparatively strong signals, a number
of weaker signals with fixed offsets relative to the actual
signal appear, the so-called „harmonics“. These are
“phantom” signals with frequencies that are multiples of
actual signals.
For example, a 400MHz signal will also be visible around
800MHz, 1200MHz, 1600MHz etc., a 1800MHz signal will
also appear at 3600MHz, 5400MHz and so forth. These are
commonly called second harmonic, third harmonic etc.
Thus; when in doubt, one should always consider an
additional measurement at half the center frequency. If a
correspondingly stronger signal is found there, the
previously measured one would be a harmonic.
With the current firmware, Spectran already attenuates
harmonics by approximately 30-50dB, depending on signal
strength.
7.3.
Measurement of wireless LAN & cellphones
To accurately measure WLAN and Cellphones, their
peculiarities need to be considered, as both systems are
rarely
„really
active
enough“
to
allow
sensible
measurements:
For measuring cellphones, you need to actively make a call
and talk. Just ringing the other party is often insufficient.
Also take into account that cellphones significantly reduce
output power as soon as you Stop talking.
When measuring WLAN, you should continuously transfer
data. Should the system be operating in “Pin”-mode only, be
sure to use a longer sample-time (5s)
Further optimized configurations can be found in our “MCS”
PC software.
