Tektronix RSA6100A Series, Help Manual

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General Signal Viewing > DPX Spectrum DPX Primer
DPX Primer
With the DPX Spectrum display you can detect and accurately measure transients as brief as 10.3 µs. The
instrument computes up to 292,000 spectrums per second (with Option 200; up to 48,833 without Option
200) of the digitized input signal. Then it displays all these spectrums as a color-graded bitmap that reveals
low-amplitude signals beneath stronger signals sharing the same frequency at different times.
The strong signal in the DPX spectrum graph, shown in Figure 1, is a repeating pulse at a fi xed frequency.
There is also a lower-power CW signal that steps very quickly through the same span. During the pulse’s
on time, the power of the two signals is additive, resulting in nearly undetectable differences in the pulse
envelope shape. But during the time the pulse is off, the sweeping signal is detected and shown in its true
form. Both signals are visible in the bitmap because at least one full cycle of their activities occurs
within a single DPX display update.
Figure 1
Compare the display of a traditional swept spectrum analyzer (Figure 2) and that of a real-time spectrum
analyzer with a DPX spectrum display (Figure 3). The signal captured is a typical WLAN interchange
between a nearby PC and a more-distant network access point (AP). The laptop signal is nearly 30 dB
stronger than the AP’s signal because it is closer to the measuring antenna.
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RSA6100A Series Real-Time Spectrum Analyzers Help