3-32 PN: 10580-00343 Rev. H S820E UG
3-7 Measurement Setup Cable and Antenna Measurements
RF Immunity
The instrument defaults to RF Immunity Low. When set to High, RF
Immunity protects the instrument from stray signals generated by nearby or
co-located transmitters that can affect frequency and DTF measurements.
The algorithm that is used to improve instrument ability to reject unwanted
signals may slow down the sweep speed if interferers are detected. If the
instrument is used in an environment where immunity is not an issue, then
the RF Immunity key can be set to Low to optimize sweep speed. Use this
feature with caution, because the introduction of an interfering signal might
be mistaken for a problem with the antenna or cable run. If Immunity is set
to Low during a normal Return Loss or VSWR measurement, then the
instrument will be more susceptible to interfering signals. Interfering signals
can make the measurement look better or worse than it really is.
1. Press the Sweep (3) menu key.
2. Toggle RF Immunity between High and Low.
RF Pwr In Hold
This setting determines if the RF output power at the RF Out/Reflect In port
stays On or is turned Off when the instrument Run/Hold setting is toggled to
Hold. When RF Pwr In Hold is set to Off, the power at the port is turned off
when the instrument is placed in Hold mode and is not sweeping. Power at
the port is resumed when the Run/Hold setting is toggled back to Run. This is
useful when you may not want a signal radiating out of the port at all times.
Smoothing
This function sets the level of smoothing applied to a frequency domain
measurement trace. A level of 0 % turns smoothing OFF. Levels 1 % through
20 % turn smoothing ON and set the smoothing percentage (the higher the
level, the higher the percentage of smoothing applied to the trace). Smoothing
is a trace averaging process that reduces or removes ripples from frequency
swept data. This is especially useful when making 1-port cable loss
measurements with a short at the other end of the cable. The ripple that is
usually present in this kind of measurement can be removed with smoothing,
thereby resulting in a more accurate average cable loss frequency response
trace. Care should be taken when applying smoothing in order to not remove
ripples that are inherent parts of the data (as opposed to measurement
artifacts).
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