Decimator Quick Tour
SED Systems, a division of Calian Ltd.
(Proprietary)
25
11. Cross-Pol Isolation Performance Testing
The 4 and 8 Port Decimators are capable of Cross-Pol Isolation Performance testing. To conduct
this test, perform the following:
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Connect one polarization RF feed (the Co-Pol) to switch port 1.
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Connect the opposite polarization RF feed (the Cross-Pol) to switch port 2.
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Run the Decimator UI in the browser.
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Click the CROSS POL button.
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Verify Switch Port is set to 1, if not adjust it to make it so.
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Verify Cross-Pol Switch Port is set to 2, if not adjust it to make it so.
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Set the Cross-Pol Mode to On
The Decimator UI captures a trace from each port, toggling back and forth. Cross-Pol style markers
are automatically added to both trace, with one at the peak of the trace and the reference marker to
the noise floor. This frequency is determined at the first trace acquisition on the minimum point in
the trace. Subsequent trace acquisitions will leave the marker at the same frequency. Users can drag
the reference noise floor marker to the desired frequency for analysis.
The system computes the C / No value for each pair of markers and renders this in the legend. This
is simply the difference between to the 2 marker values on the same trace.
A summary of the delta between these 2 C / No values is provided at the bottom of the legend for
convenience. This is the value you have to optimize as you adjust the orientation of the antenna and
observe the changes to the delta C / No summary value. Figure 31 shows the result of a recently
configured Cross-Pol testing on an 8 Port Decimator with Switch Port 1 and Cross-Pol Switch Port 2
being used.
