Tektronix SPECMON3 Manual page 54

General Signal Viewing
Simplified Flow of Multi-stage Processing from RF Input Through to Spectrum Processing:
Figure 4a. RF signals are downconverted and sampled into a continuous data stream.
Figure 4b. Samples are segmented into data records for FFT processing based on the selected resolution bandwidth.
Figure 4c. Data records are processed in the DPX transform engine
Figure 4d. Overlapping the FFTs shortens the minimum event duration required for 100% probability of intercept.
Collecting spectral data.
into data records whose length is based on the desired resolution bandwidth (RBW). An additional
requirement is placed on FFT length by the desired number of points in a trace (instruments with Option
200). Table 1 shows this relationship and the FFT length is reported in the display if desired. Then the
DPX transform engine performs a discrete Fourier transform on each record, continually producing
spectral waveforms.
RF signals are downconverted and sampled into a continuous data stream.
Samples are segmented into data records for FFT processing based on the selected resolution
bandwidth.
Data records are processed in the DPX transform engine.
Overlapped processing is used to improve minimum event duration performance.
Table 1: Minimum FFT length versus trace length – independent of span and RBW (RSA6100B Series and
RSA5100A Series with Option 200)
Trace length (points)
801
2,401
42
Sampling and digitization is continuous. The digitized data stream is chopped
Minimum FFT length
1,024
4,096
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DPX Primer