R&S FSH
Measurements using the power sensor
1145.5973.12 4.73
E-11
Press the ->REF softkey.
The R&S FSH sets the current measured level as the
reference level and from then on displays the
measured level relative to the reference level in dB.
The unit (UNIT) is automatically set to dB REL... .
The reference level is shown in the top left-hand corner
of the screen (in this case Ref: -10.4 dBm).
In the REFERENCE value entry box, the reference
level can be adjusted with the rotary knob or the cursor
keys or corrected by making a numeric entry.
Confirm the reference level with the ENTER key or
by pressing the ->REF softkey.
Setting the averaging time
The averaging time determines how long the signal will be measured for. The longer the averaging
time, the more stable the display – particularly if signals are at the lower end of the measurement range
or are noisy. The R&S FSH has three times for power measurements: fast, normal and slow.
Stationary sine signals with a high level (> -40 dBm) require only a short measurement time to produce
a stabile, accurate result. In this case, the FAST operating mode is recommended to obtain a high
repetition rate for the measurement. When the NORMAL setting is selected, the stability of the display
is increased for signals with low levels or for modulated signals. The LONG mode is recommended for
signals at the lower end of the measurement range (<-50 dBm to <-60 dBm). The R&S FSH-Z1
averages out the noise most effectively and the effect of noise on the measurement is minimal.
Press the TIME softkey.
Using the rotary knob or the cursor keys select the
measurement time you want from the menu (i.e.
SHORT, NORMAL or LONG).
Confirm your selection with the ENTER key or by
pressing the TIME softkey again.
Taking additional loss or gain into account
At high powers which cause the R&S FSH-Z1’s maximum input level to be exceeded or at very low
levels which are below the instrument's minimum sensitivity, the R&S FSH can take additional loss or
gain introduced between the DUT and the power sensor into account. These are defined in terms of an
offset in dB relative to the measured level. A positive offset corresponds to a loss and a negative offset
to a gain.
