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division shall be specified in the product specifications.
Frequency accuracy
The measured frequency shows how close the value is to the true value. It consists of absolute accuracy
and relative accuracy. The former is the actual size of the readout frequency error, and the latter is the
ratio of the readout frequency error to the ideal frequency value.
Frequency stability
Refers to the extent to which the signal frequency remains constant in the short or long term. Short-term
frequency stability is characterized by residual frequency or phase noise. Long-term frequency stability
is characterized by the aging rate.
Flatness
Corresponding to the variation of the display amplitude of the measurement frequency range of the
microwave analyzer, indicating the corresponding relationship between the displayed signal amplitude
variation and the frequency.
Sample detection method
A display detection method for signal energy, the value displayed at each point is the instantaneous
value of the video signal at a certain time interval or time interval represented by the point.
Swp Time
The time that the local oscillator passes selected frequency interval. The sweep time directly affects the
time it takes to complete a test, but does not include the dead time between completing one sweep and
starting the next sweep. At span zero , the horizontal axis is only calibrated for time. At non-span zero,
the horizontal axis calibrates both frequency and time. The sweep time typically varies with span,
resolution bandwidth and video bandwidth.
RF Attenuator
A step attenuator between the input connector and the first mixer of the microwave analyzer. The RF
attenuator is used to adjust the signal level input to the first mixer.
VBW
Refers to the bandwidth of the adjustable low-pass filter in the video loop of the microwave analyzer. The
video filter behind the detector is a low-pass filter determining the bandwidth of the video amplifier. With
the noise smoothing function, it is used to average or smooth the trace; it can easily detect weak signals
in noise. Change of the video bandwidth does not affect the frequency resolution of microwave analyzer.
However, if the selected video bandwidth is too narrow, the sweeping time would be increased.
Video filtering and video averaging
The microwave analyzer displays the measured signal plus its own internal noise. In order to reduce the
influence of noise on measuring the amplitude of the small signal, the signal to be displayed is subject
to video filtering or video averaging.
Video filtering is low-pass filtering after the envelope detector. If the video bandwidth is equal to or less
than the resolution bandwidth, the video circuit cannot fully respond to the rapid fluctuation of the
detector output, and then the display trace is smoothed. The degree of this smoothness is linked with the
ratio of video bandwidth to resolution bandwidth.
Video averaging is averaged point by point during multiple sweeps. At each point, the newly measured
data is averaged together with the previously measured data, and the display value is gradually become
the average of several measurements. It is used only on digitally displayed analyzers, the calculation of
the average is determined by the number of sweeps selected by the user. The averaging algorithm uses
the weighting factor (1/n, n is the current number of sweeps) for the given point's amplitude of current
sweep, and the other weighting factor [(n-1) /n] for the previously stored average, and then the two
values are combined into the current average. After the specified number of sweeps is completed, the
weighting coefficients remain unchanged and the display becomes dynamic average.
In most measurement situations, the video filtering and video averaging effects are essentially the same.
But there is a difference between the two, video filtering is a real-time trace smoothing; and video
averaging is fulfilled by multiple sweeps and calculating the average, thus achieving trace smoothing.
