The average power display does not match
another instrument I have. Why is this?
Some meters “convert” peak signals into an average
power value which is misleading for modern signals.
For digital signals this often results in a displayed
power level considerably higher than the real PFD.
The AM11 scales are correctly related to each other.
The levels are very low (no LEDs lit), but I can
just hear a sort of quiet hissing/burbling noise
This is the instrument picking up its own internal
electronic circuitry working and not external signals.
This only happens if the field levels are below
0.02 V/m and no LEDs are lit.
It still makes a noise when shielded behind
screening materials
The screening material may have degraded. Also,
even small gaps (including above and below you)
will let in some RF signals.
Even a 30 dB (99.9%) reduction of 10000 µW/m2 to
10 µW/m2 (a 2 V/m signal reduced to 0.06 V/m) will
still be showing and sounding on the meter.
My mobile phone is showing 1 bar of signal,
but the AM11 is reading below 0.02 V/m
Mobile phones are extremely sensitive to their
network signals and can work with extremely low
base-station signals. There is no universal meaning
for “1 bar” of signal (typically less than 0.001 V/m).
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