Tektronix WCA200A, User Manual

Page: 317 / 454

Trace Comparison Display and Average Function
WCA230A & WCA280A User Manual
3- 191
The number of bins is valid in all modes except Scalar mode. The number of
bins is meaningless in Scalar mode because it uses several physical frames to
display data. Generally, the following calculations are used:
Frequency bandwidth of one bin = (Sampling rate)/(Number of FFT points)
Number of bins = (Specified span)/(Frequency bandwidth of one bin) +1
The sampling rate varies depending on span. Refer to page A--7 in Appendix A:
Specifications for more details.
Generally, because the number of horizontal pixels on screen is smaller than the
number of bins, bin data is compressed according to the number of pixels on
screen when they are displayed (see Figure 3--132).
Data displayed on screen
(corresponds to each pixel)
Compress
Bin
Invalid data
Frame
Valid data Invalid data
Figure 3- 132: Relationships between frame, bin, and pixel
There are three types of compression methods:
Max, Min, and Max-Min (see Figure 3--133 on page 3--192).
Max is the most commonly used compression method. Max-Min is used in the
time domain waveform display in the DEMOD mode. (The compression method
is always set to Max on the spectrogram view in three-dimensional modes.)
You can select the compression method using the following steps in S/A mode:
1.
Press the
TRACE/AVG
key on the front panel.
2.
Press the
Select Trace
side key to select Trace 1 or 2.
3. Press the Display Detection... side key and select Max , Min , or Max-Min .
NOTE
. Display Detection determines how to deal with data between spectrum
display points. The analyzer performs RMS detection using the linear A/D
converter regardless of the Display Detection setting.
Compression Method
Selecting Compression
Method