Gigahertz Solutions HF59B Instruction Manual page 8

Digital High Frequency Analyser HF59B
For comparative measurements (before /
after shielding) use the same range selector
position when possible.
Power densities beyond the designed range
of the instrument (display shows "1" on its
left side with the range set on "Coarse") can
still be measured by inserting the attenuator
DG20_G3, available as an optional acces-
sory. By setting the "Adapter" switch to "At-
tenuator – 20 dB on your instrument ensures
the correct display of the measurement.
Also available are two HF preamplifiers for
factors 10 (HV10) and 1000 (HV30) as plug-
ins into the antenna input socket
cally the HF59B would have a minimum reso-
lution of 0.0001 µW/m², displayed as 0.01
Nanowatt/m². The actual minimum resolution
depends on the video bandwidth selected.
When the video Bandwidth Switch is set to:
•
TPmax (Radar) : Approx. 1 nW/m²
•
TP 30kHz (Standard) : Approx. 0.1
nW/m².
A list of all ranges, which can be measured
and displayed, is at the end of this brochure.
5
The power level adaptor switch is provided for the
factor HV10 amplifier only, not for the HV1000. The
HV1000, has the decimal point in its correct position.
The numbers are displayed in nanoW/m² instead of
µW/m² which is indicated on the LCD.
© Gigahertz Solutions GmbH, 90579 Langenzenn, Germany
Setting:
Signal Evaluation
Signal Evaluation – Average / Peak
A pulsed signal consists of sections of its
time period with high output and another
sections with zero output. Their maximum
output is the wave peak. The following illus-
tration shows the difference in the evaluation
of a pulsed signal if displayed as an average
value reading or a peak value reading.
peak value: 10
5
. Theoreti-
avg. value: 1
Note: The peak HF radiation value, not the
average value, is regarded as the measure-
ment of critical "biological effects". The peak
value is displayed in the switch setting:
"Peak". The average value is displayed in the
switch setting: "Average".
An experienced measuring technician will be
able to obtain additional information from the
comparison of average and peak values. Ba-
sic Rule: The more the two measurement
values differ from one another (in 2.4-GHz
cordless phones the ratio can be as high as
1:100.), the higher is the potential of a contri-
bution from e.g. a 2.4-GHz cordless phone or
other pulsed signal source to the total maxi-
mum value.
Still today, some field meters only display
average values. They are of little help when
considering the potential health risks associ-
HF-energy in µW/qm
e.g. 1 pulse every 10 µS
Revision 4.5 (December 2006)
ated with pulse-modulated HF radiation since
through the "averaging" of steep HF pulses,
HF radiation exposure can be underrated up
to a factor of 100, such as in 2.4-GHz cord-
less phones.
Signal Evaluation – Peak Hold
Many measuring technicians work with the
function "Signal Evaluation" "Peak Hold". In
"peak hold" mode the highest value of the
signal within a defined time span can be ob-
tained /"collected".
Clear the display with the push button "Reset
Peak Hold". While this button is pushed and
held the readings are regular "Peak" read-
ings. To start a new "Peak Hold" measure-
ment, push and hold this reset button for 2
seconds, then release it.
In everyday measurement practice this func-
tion has great value. The peak value is re-
lated to the actual signal situation. This is
important because the immission situation
can change rapidly with time, direction of the
radiation, polarization, and the points of
measurements.. The "Peak Hold" mode
guarantees that you do not miss single
peaks.
The tone signal works independently of data
collection in the peak hold mode. Its sound is
proportional to the actual value measured. It
helps to identify the location, direction, and
polarization of the maximum field strength.
You can chose the (inevitable) droop rate, at
which the held peak value decreases over
time. Set the switch below the signal evalua-
tion switch (recessed in the casing) to "Slow"
or "Fast". In "Slow" mode it takes about 20
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