Boonton 4500B Peak Power Meter - Manual (Page 171)

Boonton 4500B RF Peak Power Analyzer
Operation 4-99
4.18 DISP Key and Disp > Menu
The Display menu controls the way traces are drawn and how they appear. Use the Display > Format submenu to draw
traces as individual points, ―Points‖, or as points connected by lines, ―Lines‖. A trace can also be removed from the display
altogether by setting it to ―Off‖. The grid layout and header of the display can be selected.
The Persistence and Envelope modes provide additional help in displaying signal excursions. When the persistence and
envelope display modes are both ―Off‖, the trace is drawn as a narrow line, which shows the averaged or filtered power
reading. A single vertical pixel, representing the filtered or average power reading will be illuminated for each horizontal
trace pixel.
In Pulse mode, each pixel will be the average of one or more samples and/or sweeps, depending on timebase and
Averaging settings.
In Modulated mode, each pixel is the filtered average power, as determined by the Filter settings.
In Statistical mode, the trace is a narrow line representing the CDF, CCDF. The PDF is always drawn as a filled
distribution.
PERSISTENCE
When persistence is ―On‖ (infinite), the trace will automatically be drawn with single points (pixels) that remain visible on
the screen until cleared by pressing Display CLEAR key on the top level menu. The data points are not connected by lines
when persistence is enabled and changing any measurement or display parameters that could affect the waveform will cause
the accumulated points to be erased. This prevents invalid data from being drawn or remaining visible on the screen. Note
that the persistence mode has no effect on memory channels and only operates when the instrument is in the pulse
measurement mode.
ENVELOPE
In Pulse and Modulated modes, the Envelope display is used to highlight the range of signal excursions. When envelope
display mode is ―On‖, the trace is drawn as a wide line, which is filled in between the minimum and maximum power
readings. A series of vertical pixels, representing the range of signal excursions or "envelope" of the signal will be
illuminated for each horizontal trace pixel.
Note that for power channels, the term "envelope" refers to the range of fluctuations of the demodulated signal, NOT the "RF
Envelope". A CW signal will appear as a narrow line, since its demodulated amplitude is stable, NOT as a wide bar.
In Pulse mode, the min and max are the highest and lowest instantaneous power samples acquired during a horizontal pixel
interval. The min or max are updated on each sweep only if the acquired min or max exceed the trace's currently displayed
min or max. Before each sweep is acquired, the min and max values of the sweep are decayed towards the average reading
with a time constant proportional to the Averaging setting. This results in a "peak hold" characteristic where the min and
max peaks may be held long enough for visual identification, but are not held indefinitely. To hold the peaks longer, increase
the Chan # > Exten > Averaging setting. To maintain the min and max peaks, turn Chan # > Exten > Peak Hold ―On‖ for
the selected channel.
In Modulated mode, the min and max are the highest and lowest instantaneous power samples acquired during an acquisition
interval (typically 2ms). The min and max are decayed towards the average reading with a time constant proportional to the