Spectrum Display; Waterfall Display - Spectrum DSP M2 User Manual

DSP Setting: Middle far left is the indicator of the DSP mode button. The modes
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available are: "OFF", "NR" (Noise Reduction), "NOTCH", and "NR+NOT" (Noise
Reduction and Notch). Trace may be automatically disabled in the CPU overloads.

Spectrum display:

Below the frequency readout, shown in Figure 2 and Figure 3 is a spectrum display that
shows signals that are on either side of the current tuned frequency. Along the bottom of the
spectrum display is a frequency scale that shows the frequency scaling of the graticules
rounded to the nearest kHz.
This display works very much like a spectrum analyzer with the vertical scale being
represented logarithmically, the number of dB/division being selectable by the user. To further
the analogy to a spectrum analyzer, the "reference level" (the signal level at which a particular
strength is indicated) is automatically adjusted via an AGC (Automatic Gain Control) within the
spectrum scope that operates independently from the receiver's AGC that automatically
scales the strongest signal within the passband such that it is at/near the top of the scope –
this, to allow the representation of widely varying signals on different bands without the need
of user adjustment.

Waterfall display

Figure 4 shows an alternate
method of displaying signals
near the currently-tuned
receiver signal is the Waterfall
Display. In this mode, the
frequency is displayed along
the "X" (horizontal) axis, just as
in the case of the Spectrum
Scope but instead of the signal
strength being displayed as
height, it is displayed as relative
"brightness". The waterfall
displayed is so-called because
it can convey the history of
recent signal in time by showing
the most recent signals at the
bottom, but when new signals
are analyzed, the older signals are displaced vertically and the newest signals are placed
along the bottom. In this way, one has a quick visual "history" of what has occurred not only
on the center frequency.
Spectrum DSP M2 User Manual V1.1
Figure 4: A typical waterfall display in "Magnify" mode showing
+/- 12 kHz (24 kHz) of a band segment. When NOT in magnify
mode the waterfall will show +/-24 kHz (48kHz) of a band.
Figure 4: The waterfall display unzoomed showing +/- 96 kHz (192 kHz)
of a band segment. Zoom mode allows 96 to 3 Khz to be viewed.
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