Portable spectrum analyzer Arinst SSA-TG R2 6 April 2019
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15
igure 17 Determination of the amplitude-frequency characteristics of the equipment under test
Note. When determining the frequency response of active and passive devices, it is recommended to
use cables with a high screening coefficient. This will ensure minimization of the parasitic transmission of
electromagnetic energy from one port of the device to another port.
To reduce the influence of connecting wires and connectors on the measurement results, it is neces-
sary to normalize
Normalize
the test circuit, without the test equipment. To do this, connect the output of
the signal generator (1)
TG OUT
with the antenna input (2)
RF IN
of the device between the connectors
(cables), which will then be used to connect to the measured device and press the command
Normalize
.
When this operation is completed, the background of the
Normalize
command will turn yellow to confirm
the completion of the normalize operation.
Note. To cancel normalization, click
Normalize
again. The command background will return to the
original menu background color.
On the screen under the grid in the information label will display the mode S21 and the message
Freq.
Lock (frequency cannot change)
(Figure 17).
Note. After normalization, the setting of the frequency span of the generator output signal and analyz-
er are inaccessible. Set the frequency range of the generator output signal and analyzer before normali-
zation.
Without turning off the device, turn on the equipment under test in the circuit. The instrument will dis-
play a graph of the amplitude-frequency characteristics of the equipment under test in a given frequency
range.
Note. When changing the elements in the circuit to which the tested equipment is connected, normali-
zation should be carried out anew.
Measurement of the frequency response of active devices with known power characteristics.
To measure the frequency response of active devices, such as antenna amplifiers, with known power
characteristics, it is necessary to set the signal power of the generator and the level of signal attenuation
by the input attenuator so that the signal level from the internal oscillator of the device, before the normal-
ization operation was at-50-60 dBm.
Note. A lower signal level will lead to increased noise and non-linearity of the measured signal.
After installation, perform a normalization and measure the frequency response of the active device.
Measurement of the frequency response of active devices with unknown power characteristics.
Set the minimum output power of the internal generator and the maximum attenuation value of the in-
put attenuator of the instrument receiver. If necessary, add an additional external attenuator. Perform the
normalization operation and connect the test device to the circuit. If necessary, reduce the attenuation
level of the attenuator.
